2 * Generic process-grouping system.
4 * Based originally on the cpuset system, extracted by Paul Menage
5 * Copyright (C) 2006 Google, Inc
7 * Notifications support
8 * Copyright (C) 2009 Nokia Corporation
9 * Author: Kirill A. Shutemov
11 * Copyright notices from the original cpuset code:
12 * --------------------------------------------------
13 * Copyright (C) 2003 BULL SA.
14 * Copyright (C) 2004-2006 Silicon Graphics, Inc.
16 * Portions derived from Patrick Mochel's sysfs code.
17 * sysfs is Copyright (c) 2001-3 Patrick Mochel
19 * 2003-10-10 Written by Simon Derr.
20 * 2003-10-22 Updates by Stephen Hemminger.
21 * 2004 May-July Rework by Paul Jackson.
22 * ---------------------------------------------------
24 * This file is subject to the terms and conditions of the GNU General Public
25 * License. See the file COPYING in the main directory of the Linux
26 * distribution for more details.
29 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
31 #include "cgroup-internal.h"
33 #include <linux/cred.h>
34 #include <linux/errno.h>
35 #include <linux/init_task.h>
36 #include <linux/kernel.h>
37 #include <linux/magic.h>
38 #include <linux/mutex.h>
39 #include <linux/mount.h>
40 #include <linux/pagemap.h>
41 #include <linux/proc_fs.h>
42 #include <linux/rcupdate.h>
43 #include <linux/sched.h>
44 #include <linux/sched/task.h>
45 #include <linux/slab.h>
46 #include <linux/spinlock.h>
47 #include <linux/percpu-rwsem.h>
48 #include <linux/string.h>
49 #include <linux/hashtable.h>
50 #include <linux/idr.h>
51 #include <linux/kthread.h>
52 #include <linux/atomic.h>
53 #include <linux/cpuset.h>
54 #include <linux/proc_ns.h>
55 #include <linux/nsproxy.h>
56 #include <linux/file.h>
57 #include <linux/sched/cputime.h>
60 #define CREATE_TRACE_POINTS
61 #include <trace/events/cgroup.h>
63 #define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
65 /* let's not notify more than 100 times per second */
66 #define CGROUP_FILE_NOTIFY_MIN_INTV DIV_ROUND_UP(HZ, 100)
69 * cgroup_mutex is the master lock. Any modification to cgroup or its
70 * hierarchy must be performed while holding it.
72 * css_set_lock protects task->cgroups pointer, the list of css_set
73 * objects, and the chain of tasks off each css_set.
75 * These locks are exported if CONFIG_PROVE_RCU so that accessors in
76 * cgroup.h can use them for lockdep annotations.
78 DEFINE_MUTEX(cgroup_mutex
);
79 DEFINE_SPINLOCK(css_set_lock
);
81 #ifdef CONFIG_PROVE_RCU
82 EXPORT_SYMBOL_GPL(cgroup_mutex
);
83 EXPORT_SYMBOL_GPL(css_set_lock
);
86 DEFINE_SPINLOCK(trace_cgroup_path_lock
);
87 char trace_cgroup_path
[TRACE_CGROUP_PATH_LEN
];
90 * Protects cgroup_idr and css_idr so that IDs can be released without
91 * grabbing cgroup_mutex.
93 static DEFINE_SPINLOCK(cgroup_idr_lock
);
96 * Protects cgroup_file->kn for !self csses. It synchronizes notifications
97 * against file removal/re-creation across css hiding.
99 static DEFINE_SPINLOCK(cgroup_file_kn_lock
);
101 struct percpu_rw_semaphore cgroup_threadgroup_rwsem
;
103 #define cgroup_assert_mutex_or_rcu_locked() \
104 RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
105 !lockdep_is_held(&cgroup_mutex), \
106 "cgroup_mutex or RCU read lock required");
109 * cgroup destruction makes heavy use of work items and there can be a lot
110 * of concurrent destructions. Use a separate workqueue so that cgroup
111 * destruction work items don't end up filling up max_active of system_wq
112 * which may lead to deadlock.
114 static struct workqueue_struct
*cgroup_destroy_wq
;
116 /* generate an array of cgroup subsystem pointers */
117 #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
118 struct cgroup_subsys
*cgroup_subsys
[] = {
119 #include <linux/cgroup_subsys.h>
123 /* array of cgroup subsystem names */
124 #define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
125 static const char *cgroup_subsys_name
[] = {
126 #include <linux/cgroup_subsys.h>
130 /* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */
132 DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \
133 DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \
134 EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \
135 EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key);
136 #include <linux/cgroup_subsys.h>
139 #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key,
140 static struct static_key_true
*cgroup_subsys_enabled_key
[] = {
141 #include <linux/cgroup_subsys.h>
145 #define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key,
146 static struct static_key_true
*cgroup_subsys_on_dfl_key
[] = {
147 #include <linux/cgroup_subsys.h>
151 static DEFINE_PER_CPU(struct cgroup_rstat_cpu
, cgrp_dfl_root_rstat_cpu
);
154 * The default hierarchy, reserved for the subsystems that are otherwise
155 * unattached - it never has more than a single cgroup, and all tasks are
156 * part of that cgroup.
158 struct cgroup_root cgrp_dfl_root
= { .cgrp
.rstat_cpu
= &cgrp_dfl_root_rstat_cpu
};
159 EXPORT_SYMBOL_GPL(cgrp_dfl_root
);
162 * The default hierarchy always exists but is hidden until mounted for the
163 * first time. This is for backward compatibility.
165 static bool cgrp_dfl_visible
;
167 /* some controllers are not supported in the default hierarchy */
168 static u16 cgrp_dfl_inhibit_ss_mask
;
170 /* some controllers are implicitly enabled on the default hierarchy */
171 static u16 cgrp_dfl_implicit_ss_mask
;
173 /* some controllers can be threaded on the default hierarchy */
174 static u16 cgrp_dfl_threaded_ss_mask
;
176 /* The list of hierarchy roots */
177 LIST_HEAD(cgroup_roots
);
178 static int cgroup_root_count
;
180 /* hierarchy ID allocation and mapping, protected by cgroup_mutex */
181 static DEFINE_IDR(cgroup_hierarchy_idr
);
184 * Assign a monotonically increasing serial number to csses. It guarantees
185 * cgroups with bigger numbers are newer than those with smaller numbers.
186 * Also, as csses are always appended to the parent's ->children list, it
187 * guarantees that sibling csses are always sorted in the ascending serial
188 * number order on the list. Protected by cgroup_mutex.
190 static u64 css_serial_nr_next
= 1;
193 * These bitmasks identify subsystems with specific features to avoid
194 * having to do iterative checks repeatedly.
196 static u16 have_fork_callback __read_mostly
;
197 static u16 have_exit_callback __read_mostly
;
198 static u16 have_free_callback __read_mostly
;
199 static u16 have_canfork_callback __read_mostly
;
201 /* cgroup namespace for init task */
202 struct cgroup_namespace init_cgroup_ns
= {
203 .count
= REFCOUNT_INIT(2),
204 .user_ns
= &init_user_ns
,
205 .ns
.ops
= &cgroupns_operations
,
206 .ns
.inum
= PROC_CGROUP_INIT_INO
,
207 .root_cset
= &init_css_set
,
210 static struct file_system_type cgroup2_fs_type
;
211 static struct cftype cgroup_base_files
[];
213 static int cgroup_apply_control(struct cgroup
*cgrp
);
214 static void cgroup_finalize_control(struct cgroup
*cgrp
, int ret
);
215 static void css_task_iter_advance(struct css_task_iter
*it
);
216 static int cgroup_destroy_locked(struct cgroup
*cgrp
);
217 static struct cgroup_subsys_state
*css_create(struct cgroup
*cgrp
,
218 struct cgroup_subsys
*ss
);
219 static void css_release(struct percpu_ref
*ref
);
220 static void kill_css(struct cgroup_subsys_state
*css
);
221 static int cgroup_addrm_files(struct cgroup_subsys_state
*css
,
222 struct cgroup
*cgrp
, struct cftype cfts
[],
226 * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID
227 * @ssid: subsys ID of interest
229 * cgroup_subsys_enabled() can only be used with literal subsys names which
230 * is fine for individual subsystems but unsuitable for cgroup core. This
231 * is slower static_key_enabled() based test indexed by @ssid.
233 bool cgroup_ssid_enabled(int ssid
)
235 if (CGROUP_SUBSYS_COUNT
== 0)
238 return static_key_enabled(cgroup_subsys_enabled_key
[ssid
]);
242 * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
243 * @cgrp: the cgroup of interest
245 * The default hierarchy is the v2 interface of cgroup and this function
246 * can be used to test whether a cgroup is on the default hierarchy for
247 * cases where a subsystem should behave differnetly depending on the
250 * The set of behaviors which change on the default hierarchy are still
251 * being determined and the mount option is prefixed with __DEVEL__.
253 * List of changed behaviors:
255 * - Mount options "noprefix", "xattr", "clone_children", "release_agent"
256 * and "name" are disallowed.
258 * - When mounting an existing superblock, mount options should match.
260 * - Remount is disallowed.
262 * - rename(2) is disallowed.
264 * - "tasks" is removed. Everything should be at process granularity. Use
265 * "cgroup.procs" instead.
267 * - "cgroup.procs" is not sorted. pids will be unique unless they got
268 * recycled inbetween reads.
270 * - "release_agent" and "notify_on_release" are removed. Replacement
271 * notification mechanism will be implemented.
273 * - "cgroup.clone_children" is removed.
275 * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
276 * and its descendants contain no task; otherwise, 1. The file also
277 * generates kernfs notification which can be monitored through poll and
278 * [di]notify when the value of the file changes.
280 * - cpuset: tasks will be kept in empty cpusets when hotplug happens and
281 * take masks of ancestors with non-empty cpus/mems, instead of being
282 * moved to an ancestor.
284 * - cpuset: a task can be moved into an empty cpuset, and again it takes
285 * masks of ancestors.
287 * - memcg: use_hierarchy is on by default and the cgroup file for the flag
290 * - blkcg: blk-throttle becomes properly hierarchical.
292 * - debug: disallowed on the default hierarchy.
294 bool cgroup_on_dfl(const struct cgroup
*cgrp
)
296 return cgrp
->root
== &cgrp_dfl_root
;
299 /* IDR wrappers which synchronize using cgroup_idr_lock */
300 static int cgroup_idr_alloc(struct idr
*idr
, void *ptr
, int start
, int end
,
305 idr_preload(gfp_mask
);
306 spin_lock_bh(&cgroup_idr_lock
);
307 ret
= idr_alloc(idr
, ptr
, start
, end
, gfp_mask
& ~__GFP_DIRECT_RECLAIM
);
308 spin_unlock_bh(&cgroup_idr_lock
);
313 static void *cgroup_idr_replace(struct idr
*idr
, void *ptr
, int id
)
317 spin_lock_bh(&cgroup_idr_lock
);
318 ret
= idr_replace(idr
, ptr
, id
);
319 spin_unlock_bh(&cgroup_idr_lock
);
323 static void cgroup_idr_remove(struct idr
*idr
, int id
)
325 spin_lock_bh(&cgroup_idr_lock
);
327 spin_unlock_bh(&cgroup_idr_lock
);
330 static bool cgroup_has_tasks(struct cgroup
*cgrp
)
332 return cgrp
->nr_populated_csets
;
335 bool cgroup_is_threaded(struct cgroup
*cgrp
)
337 return cgrp
->dom_cgrp
!= cgrp
;
340 /* can @cgrp host both domain and threaded children? */
341 static bool cgroup_is_mixable(struct cgroup
*cgrp
)
344 * Root isn't under domain level resource control exempting it from
345 * the no-internal-process constraint, so it can serve as a thread
346 * root and a parent of resource domains at the same time.
348 return !cgroup_parent(cgrp
);
351 /* can @cgrp become a thread root? should always be true for a thread root */
352 static bool cgroup_can_be_thread_root(struct cgroup
*cgrp
)
354 /* mixables don't care */
355 if (cgroup_is_mixable(cgrp
))
358 /* domain roots can't be nested under threaded */
359 if (cgroup_is_threaded(cgrp
))
362 /* can only have either domain or threaded children */
363 if (cgrp
->nr_populated_domain_children
)
366 /* and no domain controllers can be enabled */
367 if (cgrp
->subtree_control
& ~cgrp_dfl_threaded_ss_mask
)
373 /* is @cgrp root of a threaded subtree? */
374 bool cgroup_is_thread_root(struct cgroup
*cgrp
)
376 /* thread root should be a domain */
377 if (cgroup_is_threaded(cgrp
))
380 /* a domain w/ threaded children is a thread root */
381 if (cgrp
->nr_threaded_children
)
385 * A domain which has tasks and explicit threaded controllers
386 * enabled is a thread root.
388 if (cgroup_has_tasks(cgrp
) &&
389 (cgrp
->subtree_control
& cgrp_dfl_threaded_ss_mask
))
395 /* a domain which isn't connected to the root w/o brekage can't be used */
396 static bool cgroup_is_valid_domain(struct cgroup
*cgrp
)
398 /* the cgroup itself can be a thread root */
399 if (cgroup_is_threaded(cgrp
))
402 /* but the ancestors can't be unless mixable */
403 while ((cgrp
= cgroup_parent(cgrp
))) {
404 if (!cgroup_is_mixable(cgrp
) && cgroup_is_thread_root(cgrp
))
406 if (cgroup_is_threaded(cgrp
))
413 /* subsystems visibly enabled on a cgroup */
414 static u16
cgroup_control(struct cgroup
*cgrp
)
416 struct cgroup
*parent
= cgroup_parent(cgrp
);
417 u16 root_ss_mask
= cgrp
->root
->subsys_mask
;
420 u16 ss_mask
= parent
->subtree_control
;
422 /* threaded cgroups can only have threaded controllers */
423 if (cgroup_is_threaded(cgrp
))
424 ss_mask
&= cgrp_dfl_threaded_ss_mask
;
428 if (cgroup_on_dfl(cgrp
))
429 root_ss_mask
&= ~(cgrp_dfl_inhibit_ss_mask
|
430 cgrp_dfl_implicit_ss_mask
);
434 /* subsystems enabled on a cgroup */
435 static u16
cgroup_ss_mask(struct cgroup
*cgrp
)
437 struct cgroup
*parent
= cgroup_parent(cgrp
);
440 u16 ss_mask
= parent
->subtree_ss_mask
;
442 /* threaded cgroups can only have threaded controllers */
443 if (cgroup_is_threaded(cgrp
))
444 ss_mask
&= cgrp_dfl_threaded_ss_mask
;
448 return cgrp
->root
->subsys_mask
;
452 * cgroup_css - obtain a cgroup's css for the specified subsystem
453 * @cgrp: the cgroup of interest
454 * @ss: the subsystem of interest (%NULL returns @cgrp->self)
456 * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
457 * function must be called either under cgroup_mutex or rcu_read_lock() and
458 * the caller is responsible for pinning the returned css if it wants to
459 * keep accessing it outside the said locks. This function may return
460 * %NULL if @cgrp doesn't have @subsys_id enabled.
462 static struct cgroup_subsys_state
*cgroup_css(struct cgroup
*cgrp
,
463 struct cgroup_subsys
*ss
)
466 return rcu_dereference_check(cgrp
->subsys
[ss
->id
],
467 lockdep_is_held(&cgroup_mutex
));
473 * cgroup_tryget_css - try to get a cgroup's css for the specified subsystem
474 * @cgrp: the cgroup of interest
475 * @ss: the subsystem of interest
477 * Find and get @cgrp's css assocaited with @ss. If the css doesn't exist
478 * or is offline, %NULL is returned.
480 static struct cgroup_subsys_state
*cgroup_tryget_css(struct cgroup
*cgrp
,
481 struct cgroup_subsys
*ss
)
483 struct cgroup_subsys_state
*css
;
486 css
= cgroup_css(cgrp
, ss
);
487 if (!css
|| !css_tryget_online(css
))
495 * cgroup_e_css_by_mask - obtain a cgroup's effective css for the specified ss
496 * @cgrp: the cgroup of interest
497 * @ss: the subsystem of interest (%NULL returns @cgrp->self)
499 * Similar to cgroup_css() but returns the effective css, which is defined
500 * as the matching css of the nearest ancestor including self which has @ss
501 * enabled. If @ss is associated with the hierarchy @cgrp is on, this
502 * function is guaranteed to return non-NULL css.
504 static struct cgroup_subsys_state
*cgroup_e_css_by_mask(struct cgroup
*cgrp
,
505 struct cgroup_subsys
*ss
)
507 lockdep_assert_held(&cgroup_mutex
);
513 * This function is used while updating css associations and thus
514 * can't test the csses directly. Test ss_mask.
516 while (!(cgroup_ss_mask(cgrp
) & (1 << ss
->id
))) {
517 cgrp
= cgroup_parent(cgrp
);
522 return cgroup_css(cgrp
, ss
);
526 * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem
527 * @cgrp: the cgroup of interest
528 * @ss: the subsystem of interest
530 * Find and get the effective css of @cgrp for @ss. The effective css is
531 * defined as the matching css of the nearest ancestor including self which
532 * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
533 * the root css is returned, so this function always returns a valid css.
535 * The returned css is not guaranteed to be online, and therefore it is the
536 * callers responsiblity to tryget a reference for it.
538 struct cgroup_subsys_state
*cgroup_e_css(struct cgroup
*cgrp
,
539 struct cgroup_subsys
*ss
)
541 struct cgroup_subsys_state
*css
;
544 css
= cgroup_css(cgrp
, ss
);
548 cgrp
= cgroup_parent(cgrp
);
551 return init_css_set
.subsys
[ss
->id
];
555 * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem
556 * @cgrp: the cgroup of interest
557 * @ss: the subsystem of interest
559 * Find and get the effective css of @cgrp for @ss. The effective css is
560 * defined as the matching css of the nearest ancestor including self which
561 * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
562 * the root css is returned, so this function always returns a valid css.
563 * The returned css must be put using css_put().
565 struct cgroup_subsys_state
*cgroup_get_e_css(struct cgroup
*cgrp
,
566 struct cgroup_subsys
*ss
)
568 struct cgroup_subsys_state
*css
;
573 css
= cgroup_css(cgrp
, ss
);
575 if (css
&& css_tryget_online(css
))
577 cgrp
= cgroup_parent(cgrp
);
580 css
= init_css_set
.subsys
[ss
->id
];
587 static void cgroup_get_live(struct cgroup
*cgrp
)
589 WARN_ON_ONCE(cgroup_is_dead(cgrp
));
590 css_get(&cgrp
->self
);
593 struct cgroup_subsys_state
*of_css(struct kernfs_open_file
*of
)
595 struct cgroup
*cgrp
= of
->kn
->parent
->priv
;
596 struct cftype
*cft
= of_cft(of
);
599 * This is open and unprotected implementation of cgroup_css().
600 * seq_css() is only called from a kernfs file operation which has
601 * an active reference on the file. Because all the subsystem
602 * files are drained before a css is disassociated with a cgroup,
603 * the matching css from the cgroup's subsys table is guaranteed to
604 * be and stay valid until the enclosing operation is complete.
607 return rcu_dereference_raw(cgrp
->subsys
[cft
->ss
->id
]);
611 EXPORT_SYMBOL_GPL(of_css
);
614 * for_each_css - iterate all css's of a cgroup
615 * @css: the iteration cursor
616 * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
617 * @cgrp: the target cgroup to iterate css's of
619 * Should be called under cgroup_[tree_]mutex.
621 #define for_each_css(css, ssid, cgrp) \
622 for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
623 if (!((css) = rcu_dereference_check( \
624 (cgrp)->subsys[(ssid)], \
625 lockdep_is_held(&cgroup_mutex)))) { } \
629 * for_each_e_css - iterate all effective css's of a cgroup
630 * @css: the iteration cursor
631 * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
632 * @cgrp: the target cgroup to iterate css's of
634 * Should be called under cgroup_[tree_]mutex.
636 #define for_each_e_css(css, ssid, cgrp) \
637 for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
638 if (!((css) = cgroup_e_css_by_mask(cgrp, \
639 cgroup_subsys[(ssid)]))) \
644 * do_each_subsys_mask - filter for_each_subsys with a bitmask
645 * @ss: the iteration cursor
646 * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
647 * @ss_mask: the bitmask
649 * The block will only run for cases where the ssid-th bit (1 << ssid) of
652 #define do_each_subsys_mask(ss, ssid, ss_mask) do { \
653 unsigned long __ss_mask = (ss_mask); \
654 if (!CGROUP_SUBSYS_COUNT) { /* to avoid spurious gcc warning */ \
658 for_each_set_bit(ssid, &__ss_mask, CGROUP_SUBSYS_COUNT) { \
659 (ss) = cgroup_subsys[ssid]; \
662 #define while_each_subsys_mask() \
667 /* iterate over child cgrps, lock should be held throughout iteration */
668 #define cgroup_for_each_live_child(child, cgrp) \
669 list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \
670 if (({ lockdep_assert_held(&cgroup_mutex); \
671 cgroup_is_dead(child); })) \
675 /* walk live descendants in preorder */
676 #define cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) \
677 css_for_each_descendant_pre((d_css), cgroup_css((cgrp), NULL)) \
678 if (({ lockdep_assert_held(&cgroup_mutex); \
679 (dsct) = (d_css)->cgroup; \
680 cgroup_is_dead(dsct); })) \
684 /* walk live descendants in postorder */
685 #define cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) \
686 css_for_each_descendant_post((d_css), cgroup_css((cgrp), NULL)) \
687 if (({ lockdep_assert_held(&cgroup_mutex); \
688 (dsct) = (d_css)->cgroup; \
689 cgroup_is_dead(dsct); })) \
694 * The default css_set - used by init and its children prior to any
695 * hierarchies being mounted. It contains a pointer to the root state
696 * for each subsystem. Also used to anchor the list of css_sets. Not
697 * reference-counted, to improve performance when child cgroups
698 * haven't been created.
700 struct css_set init_css_set
= {
701 .refcount
= REFCOUNT_INIT(1),
702 .dom_cset
= &init_css_set
,
703 .tasks
= LIST_HEAD_INIT(init_css_set
.tasks
),
704 .mg_tasks
= LIST_HEAD_INIT(init_css_set
.mg_tasks
),
705 .task_iters
= LIST_HEAD_INIT(init_css_set
.task_iters
),
706 .threaded_csets
= LIST_HEAD_INIT(init_css_set
.threaded_csets
),
707 .cgrp_links
= LIST_HEAD_INIT(init_css_set
.cgrp_links
),
708 .mg_preload_node
= LIST_HEAD_INIT(init_css_set
.mg_preload_node
),
709 .mg_node
= LIST_HEAD_INIT(init_css_set
.mg_node
),
712 * The following field is re-initialized when this cset gets linked
713 * in cgroup_init(). However, let's initialize the field
714 * statically too so that the default cgroup can be accessed safely
717 .dfl_cgrp
= &cgrp_dfl_root
.cgrp
,
720 static int css_set_count
= 1; /* 1 for init_css_set */
722 static bool css_set_threaded(struct css_set
*cset
)
724 return cset
->dom_cset
!= cset
;
728 * css_set_populated - does a css_set contain any tasks?
729 * @cset: target css_set
731 * css_set_populated() should be the same as !!cset->nr_tasks at steady
732 * state. However, css_set_populated() can be called while a task is being
733 * added to or removed from the linked list before the nr_tasks is
734 * properly updated. Hence, we can't just look at ->nr_tasks here.
736 static bool css_set_populated(struct css_set
*cset
)
738 lockdep_assert_held(&css_set_lock
);
740 return !list_empty(&cset
->tasks
) || !list_empty(&cset
->mg_tasks
);
744 * cgroup_update_populated - update the populated count of a cgroup
745 * @cgrp: the target cgroup
746 * @populated: inc or dec populated count
748 * One of the css_sets associated with @cgrp is either getting its first
749 * task or losing the last. Update @cgrp->nr_populated_* accordingly. The
750 * count is propagated towards root so that a given cgroup's
751 * nr_populated_children is zero iff none of its descendants contain any
754 * @cgrp's interface file "cgroup.populated" is zero if both
755 * @cgrp->nr_populated_csets and @cgrp->nr_populated_children are zero and
756 * 1 otherwise. When the sum changes from or to zero, userland is notified
757 * that the content of the interface file has changed. This can be used to
758 * detect when @cgrp and its descendants become populated or empty.
760 static void cgroup_update_populated(struct cgroup
*cgrp
, bool populated
)
762 struct cgroup
*child
= NULL
;
763 int adj
= populated
? 1 : -1;
765 lockdep_assert_held(&css_set_lock
);
768 bool was_populated
= cgroup_is_populated(cgrp
);
771 cgrp
->nr_populated_csets
+= adj
;
773 if (cgroup_is_threaded(child
))
774 cgrp
->nr_populated_threaded_children
+= adj
;
776 cgrp
->nr_populated_domain_children
+= adj
;
779 if (was_populated
== cgroup_is_populated(cgrp
))
782 cgroup1_check_for_release(cgrp
);
783 cgroup_file_notify(&cgrp
->events_file
);
786 cgrp
= cgroup_parent(cgrp
);
791 * css_set_update_populated - update populated state of a css_set
792 * @cset: target css_set
793 * @populated: whether @cset is populated or depopulated
795 * @cset is either getting the first task or losing the last. Update the
796 * populated counters of all associated cgroups accordingly.
798 static void css_set_update_populated(struct css_set
*cset
, bool populated
)
800 struct cgrp_cset_link
*link
;
802 lockdep_assert_held(&css_set_lock
);
804 list_for_each_entry(link
, &cset
->cgrp_links
, cgrp_link
)
805 cgroup_update_populated(link
->cgrp
, populated
);
809 * css_set_move_task - move a task from one css_set to another
810 * @task: task being moved
811 * @from_cset: css_set @task currently belongs to (may be NULL)
812 * @to_cset: new css_set @task is being moved to (may be NULL)
813 * @use_mg_tasks: move to @to_cset->mg_tasks instead of ->tasks
815 * Move @task from @from_cset to @to_cset. If @task didn't belong to any
816 * css_set, @from_cset can be NULL. If @task is being disassociated
817 * instead of moved, @to_cset can be NULL.
819 * This function automatically handles populated counter updates and
820 * css_task_iter adjustments but the caller is responsible for managing
821 * @from_cset and @to_cset's reference counts.
823 static void css_set_move_task(struct task_struct
*task
,
824 struct css_set
*from_cset
, struct css_set
*to_cset
,
827 lockdep_assert_held(&css_set_lock
);
829 if (to_cset
&& !css_set_populated(to_cset
))
830 css_set_update_populated(to_cset
, true);
833 struct css_task_iter
*it
, *pos
;
835 WARN_ON_ONCE(list_empty(&task
->cg_list
));
838 * @task is leaving, advance task iterators which are
839 * pointing to it so that they can resume at the next
840 * position. Advancing an iterator might remove it from
841 * the list, use safe walk. See css_task_iter_advance*()
844 list_for_each_entry_safe(it
, pos
, &from_cset
->task_iters
,
846 if (it
->task_pos
== &task
->cg_list
)
847 css_task_iter_advance(it
);
849 list_del_init(&task
->cg_list
);
850 if (!css_set_populated(from_cset
))
851 css_set_update_populated(from_cset
, false);
853 WARN_ON_ONCE(!list_empty(&task
->cg_list
));
858 * We are synchronized through cgroup_threadgroup_rwsem
859 * against PF_EXITING setting such that we can't race
860 * against cgroup_exit() changing the css_set to
861 * init_css_set and dropping the old one.
863 WARN_ON_ONCE(task
->flags
& PF_EXITING
);
865 rcu_assign_pointer(task
->cgroups
, to_cset
);
866 list_add_tail(&task
->cg_list
, use_mg_tasks
? &to_cset
->mg_tasks
:
872 * hash table for cgroup groups. This improves the performance to find
873 * an existing css_set. This hash doesn't (currently) take into
874 * account cgroups in empty hierarchies.
876 #define CSS_SET_HASH_BITS 7
877 static DEFINE_HASHTABLE(css_set_table
, CSS_SET_HASH_BITS
);
879 static unsigned long css_set_hash(struct cgroup_subsys_state
*css
[])
881 unsigned long key
= 0UL;
882 struct cgroup_subsys
*ss
;
885 for_each_subsys(ss
, i
)
886 key
+= (unsigned long)css
[i
];
887 key
= (key
>> 16) ^ key
;
892 void put_css_set_locked(struct css_set
*cset
)
894 struct cgrp_cset_link
*link
, *tmp_link
;
895 struct cgroup_subsys
*ss
;
898 lockdep_assert_held(&css_set_lock
);
900 if (!refcount_dec_and_test(&cset
->refcount
))
903 WARN_ON_ONCE(!list_empty(&cset
->threaded_csets
));
905 /* This css_set is dead. unlink it and release cgroup and css refs */
906 for_each_subsys(ss
, ssid
) {
907 list_del(&cset
->e_cset_node
[ssid
]);
908 css_put(cset
->subsys
[ssid
]);
910 hash_del(&cset
->hlist
);
913 list_for_each_entry_safe(link
, tmp_link
, &cset
->cgrp_links
, cgrp_link
) {
914 list_del(&link
->cset_link
);
915 list_del(&link
->cgrp_link
);
916 if (cgroup_parent(link
->cgrp
))
917 cgroup_put(link
->cgrp
);
921 if (css_set_threaded(cset
)) {
922 list_del(&cset
->threaded_csets_node
);
923 put_css_set_locked(cset
->dom_cset
);
926 kfree_rcu(cset
, rcu_head
);
930 * compare_css_sets - helper function for find_existing_css_set().
931 * @cset: candidate css_set being tested
932 * @old_cset: existing css_set for a task
933 * @new_cgrp: cgroup that's being entered by the task
934 * @template: desired set of css pointers in css_set (pre-calculated)
936 * Returns true if "cset" matches "old_cset" except for the hierarchy
937 * which "new_cgrp" belongs to, for which it should match "new_cgrp".
939 static bool compare_css_sets(struct css_set
*cset
,
940 struct css_set
*old_cset
,
941 struct cgroup
*new_cgrp
,
942 struct cgroup_subsys_state
*template[])
944 struct cgroup
*new_dfl_cgrp
;
945 struct list_head
*l1
, *l2
;
948 * On the default hierarchy, there can be csets which are
949 * associated with the same set of cgroups but different csses.
950 * Let's first ensure that csses match.
952 if (memcmp(template, cset
->subsys
, sizeof(cset
->subsys
)))
956 /* @cset's domain should match the default cgroup's */
957 if (cgroup_on_dfl(new_cgrp
))
958 new_dfl_cgrp
= new_cgrp
;
960 new_dfl_cgrp
= old_cset
->dfl_cgrp
;
962 if (new_dfl_cgrp
->dom_cgrp
!= cset
->dom_cset
->dfl_cgrp
)
966 * Compare cgroup pointers in order to distinguish between
967 * different cgroups in hierarchies. As different cgroups may
968 * share the same effective css, this comparison is always
971 l1
= &cset
->cgrp_links
;
972 l2
= &old_cset
->cgrp_links
;
974 struct cgrp_cset_link
*link1
, *link2
;
975 struct cgroup
*cgrp1
, *cgrp2
;
979 /* See if we reached the end - both lists are equal length. */
980 if (l1
== &cset
->cgrp_links
) {
981 BUG_ON(l2
!= &old_cset
->cgrp_links
);
984 BUG_ON(l2
== &old_cset
->cgrp_links
);
986 /* Locate the cgroups associated with these links. */
987 link1
= list_entry(l1
, struct cgrp_cset_link
, cgrp_link
);
988 link2
= list_entry(l2
, struct cgrp_cset_link
, cgrp_link
);
991 /* Hierarchies should be linked in the same order. */
992 BUG_ON(cgrp1
->root
!= cgrp2
->root
);
995 * If this hierarchy is the hierarchy of the cgroup
996 * that's changing, then we need to check that this
997 * css_set points to the new cgroup; if it's any other
998 * hierarchy, then this css_set should point to the
999 * same cgroup as the old css_set.
1001 if (cgrp1
->root
== new_cgrp
->root
) {
1002 if (cgrp1
!= new_cgrp
)
1013 * find_existing_css_set - init css array and find the matching css_set
1014 * @old_cset: the css_set that we're using before the cgroup transition
1015 * @cgrp: the cgroup that we're moving into
1016 * @template: out param for the new set of csses, should be clear on entry
1018 static struct css_set
*find_existing_css_set(struct css_set
*old_cset
,
1019 struct cgroup
*cgrp
,
1020 struct cgroup_subsys_state
*template[])
1022 struct cgroup_root
*root
= cgrp
->root
;
1023 struct cgroup_subsys
*ss
;
1024 struct css_set
*cset
;
1029 * Build the set of subsystem state objects that we want to see in the
1030 * new css_set. while subsystems can change globally, the entries here
1031 * won't change, so no need for locking.
1033 for_each_subsys(ss
, i
) {
1034 if (root
->subsys_mask
& (1UL << i
)) {
1036 * @ss is in this hierarchy, so we want the
1037 * effective css from @cgrp.
1039 template[i
] = cgroup_e_css_by_mask(cgrp
, ss
);
1042 * @ss is not in this hierarchy, so we don't want
1043 * to change the css.
1045 template[i
] = old_cset
->subsys
[i
];
1049 key
= css_set_hash(template);
1050 hash_for_each_possible(css_set_table
, cset
, hlist
, key
) {
1051 if (!compare_css_sets(cset
, old_cset
, cgrp
, template))
1054 /* This css_set matches what we need */
1058 /* No existing cgroup group matched */
1062 static void free_cgrp_cset_links(struct list_head
*links_to_free
)
1064 struct cgrp_cset_link
*link
, *tmp_link
;
1066 list_for_each_entry_safe(link
, tmp_link
, links_to_free
, cset_link
) {
1067 list_del(&link
->cset_link
);
1073 * allocate_cgrp_cset_links - allocate cgrp_cset_links
1074 * @count: the number of links to allocate
1075 * @tmp_links: list_head the allocated links are put on
1077 * Allocate @count cgrp_cset_link structures and chain them on @tmp_links
1078 * through ->cset_link. Returns 0 on success or -errno.
1080 static int allocate_cgrp_cset_links(int count
, struct list_head
*tmp_links
)
1082 struct cgrp_cset_link
*link
;
1085 INIT_LIST_HEAD(tmp_links
);
1087 for (i
= 0; i
< count
; i
++) {
1088 link
= kzalloc(sizeof(*link
), GFP_KERNEL
);
1090 free_cgrp_cset_links(tmp_links
);
1093 list_add(&link
->cset_link
, tmp_links
);
1099 * link_css_set - a helper function to link a css_set to a cgroup
1100 * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
1101 * @cset: the css_set to be linked
1102 * @cgrp: the destination cgroup
1104 static void link_css_set(struct list_head
*tmp_links
, struct css_set
*cset
,
1105 struct cgroup
*cgrp
)
1107 struct cgrp_cset_link
*link
;
1109 BUG_ON(list_empty(tmp_links
));
1111 if (cgroup_on_dfl(cgrp
))
1112 cset
->dfl_cgrp
= cgrp
;
1114 link
= list_first_entry(tmp_links
, struct cgrp_cset_link
, cset_link
);
1119 * Always add links to the tail of the lists so that the lists are
1120 * in choronological order.
1122 list_move_tail(&link
->cset_link
, &cgrp
->cset_links
);
1123 list_add_tail(&link
->cgrp_link
, &cset
->cgrp_links
);
1125 if (cgroup_parent(cgrp
))
1126 cgroup_get_live(cgrp
);
1130 * find_css_set - return a new css_set with one cgroup updated
1131 * @old_cset: the baseline css_set
1132 * @cgrp: the cgroup to be updated
1134 * Return a new css_set that's equivalent to @old_cset, but with @cgrp
1135 * substituted into the appropriate hierarchy.
1137 static struct css_set
*find_css_set(struct css_set
*old_cset
,
1138 struct cgroup
*cgrp
)
1140 struct cgroup_subsys_state
*template[CGROUP_SUBSYS_COUNT
] = { };
1141 struct css_set
*cset
;
1142 struct list_head tmp_links
;
1143 struct cgrp_cset_link
*link
;
1144 struct cgroup_subsys
*ss
;
1148 lockdep_assert_held(&cgroup_mutex
);
1150 /* First see if we already have a cgroup group that matches
1151 * the desired set */
1152 spin_lock_irq(&css_set_lock
);
1153 cset
= find_existing_css_set(old_cset
, cgrp
, template);
1156 spin_unlock_irq(&css_set_lock
);
1161 cset
= kzalloc(sizeof(*cset
), GFP_KERNEL
);
1165 /* Allocate all the cgrp_cset_link objects that we'll need */
1166 if (allocate_cgrp_cset_links(cgroup_root_count
, &tmp_links
) < 0) {
1171 refcount_set(&cset
->refcount
, 1);
1172 cset
->dom_cset
= cset
;
1173 INIT_LIST_HEAD(&cset
->tasks
);
1174 INIT_LIST_HEAD(&cset
->mg_tasks
);
1175 INIT_LIST_HEAD(&cset
->task_iters
);
1176 INIT_LIST_HEAD(&cset
->threaded_csets
);
1177 INIT_HLIST_NODE(&cset
->hlist
);
1178 INIT_LIST_HEAD(&cset
->cgrp_links
);
1179 INIT_LIST_HEAD(&cset
->mg_preload_node
);
1180 INIT_LIST_HEAD(&cset
->mg_node
);
1182 /* Copy the set of subsystem state objects generated in
1183 * find_existing_css_set() */
1184 memcpy(cset
->subsys
, template, sizeof(cset
->subsys
));
1186 spin_lock_irq(&css_set_lock
);
1187 /* Add reference counts and links from the new css_set. */
1188 list_for_each_entry(link
, &old_cset
->cgrp_links
, cgrp_link
) {
1189 struct cgroup
*c
= link
->cgrp
;
1191 if (c
->root
== cgrp
->root
)
1193 link_css_set(&tmp_links
, cset
, c
);
1196 BUG_ON(!list_empty(&tmp_links
));
1200 /* Add @cset to the hash table */
1201 key
= css_set_hash(cset
->subsys
);
1202 hash_add(css_set_table
, &cset
->hlist
, key
);
1204 for_each_subsys(ss
, ssid
) {
1205 struct cgroup_subsys_state
*css
= cset
->subsys
[ssid
];
1207 list_add_tail(&cset
->e_cset_node
[ssid
],
1208 &css
->cgroup
->e_csets
[ssid
]);
1212 spin_unlock_irq(&css_set_lock
);
1215 * If @cset should be threaded, look up the matching dom_cset and
1216 * link them up. We first fully initialize @cset then look for the
1217 * dom_cset. It's simpler this way and safe as @cset is guaranteed
1218 * to stay empty until we return.
1220 if (cgroup_is_threaded(cset
->dfl_cgrp
)) {
1221 struct css_set
*dcset
;
1223 dcset
= find_css_set(cset
, cset
->dfl_cgrp
->dom_cgrp
);
1229 spin_lock_irq(&css_set_lock
);
1230 cset
->dom_cset
= dcset
;
1231 list_add_tail(&cset
->threaded_csets_node
,
1232 &dcset
->threaded_csets
);
1233 spin_unlock_irq(&css_set_lock
);
1239 struct cgroup_root
*cgroup_root_from_kf(struct kernfs_root
*kf_root
)
1241 struct cgroup
*root_cgrp
= kf_root
->kn
->priv
;
1243 return root_cgrp
->root
;
1246 static int cgroup_init_root_id(struct cgroup_root
*root
)
1250 lockdep_assert_held(&cgroup_mutex
);
1252 id
= idr_alloc_cyclic(&cgroup_hierarchy_idr
, root
, 0, 0, GFP_KERNEL
);
1256 root
->hierarchy_id
= id
;
1260 static void cgroup_exit_root_id(struct cgroup_root
*root
)
1262 lockdep_assert_held(&cgroup_mutex
);
1264 idr_remove(&cgroup_hierarchy_idr
, root
->hierarchy_id
);
1267 void cgroup_free_root(struct cgroup_root
*root
)
1270 idr_destroy(&root
->cgroup_idr
);
1275 static void cgroup_destroy_root(struct cgroup_root
*root
)
1277 struct cgroup
*cgrp
= &root
->cgrp
;
1278 struct cgrp_cset_link
*link
, *tmp_link
;
1280 trace_cgroup_destroy_root(root
);
1282 cgroup_lock_and_drain_offline(&cgrp_dfl_root
.cgrp
);
1284 BUG_ON(atomic_read(&root
->nr_cgrps
));
1285 BUG_ON(!list_empty(&cgrp
->self
.children
));
1287 /* Rebind all subsystems back to the default hierarchy */
1288 WARN_ON(rebind_subsystems(&cgrp_dfl_root
, root
->subsys_mask
));
1291 * Release all the links from cset_links to this hierarchy's
1294 spin_lock_irq(&css_set_lock
);
1296 list_for_each_entry_safe(link
, tmp_link
, &cgrp
->cset_links
, cset_link
) {
1297 list_del(&link
->cset_link
);
1298 list_del(&link
->cgrp_link
);
1302 spin_unlock_irq(&css_set_lock
);
1304 if (!list_empty(&root
->root_list
)) {
1305 list_del(&root
->root_list
);
1306 cgroup_root_count
--;
1309 cgroup_exit_root_id(root
);
1311 mutex_unlock(&cgroup_mutex
);
1313 kernfs_destroy_root(root
->kf_root
);
1314 cgroup_free_root(root
);
1318 * look up cgroup associated with current task's cgroup namespace on the
1319 * specified hierarchy
1321 static struct cgroup
*
1322 current_cgns_cgroup_from_root(struct cgroup_root
*root
)
1324 struct cgroup
*res
= NULL
;
1325 struct css_set
*cset
;
1327 lockdep_assert_held(&css_set_lock
);
1331 cset
= current
->nsproxy
->cgroup_ns
->root_cset
;
1332 if (cset
== &init_css_set
) {
1335 struct cgrp_cset_link
*link
;
1337 list_for_each_entry(link
, &cset
->cgrp_links
, cgrp_link
) {
1338 struct cgroup
*c
= link
->cgrp
;
1340 if (c
->root
== root
) {
1352 /* look up cgroup associated with given css_set on the specified hierarchy */
1353 static struct cgroup
*cset_cgroup_from_root(struct css_set
*cset
,
1354 struct cgroup_root
*root
)
1356 struct cgroup
*res
= NULL
;
1358 lockdep_assert_held(&cgroup_mutex
);
1359 lockdep_assert_held(&css_set_lock
);
1361 if (cset
== &init_css_set
) {
1363 } else if (root
== &cgrp_dfl_root
) {
1364 res
= cset
->dfl_cgrp
;
1366 struct cgrp_cset_link
*link
;
1368 list_for_each_entry(link
, &cset
->cgrp_links
, cgrp_link
) {
1369 struct cgroup
*c
= link
->cgrp
;
1371 if (c
->root
== root
) {
1383 * Return the cgroup for "task" from the given hierarchy. Must be
1384 * called with cgroup_mutex and css_set_lock held.
1386 struct cgroup
*task_cgroup_from_root(struct task_struct
*task
,
1387 struct cgroup_root
*root
)
1390 * No need to lock the task - since we hold cgroup_mutex the
1391 * task can't change groups, so the only thing that can happen
1392 * is that it exits and its css is set back to init_css_set.
1394 return cset_cgroup_from_root(task_css_set(task
), root
);
1398 * A task must hold cgroup_mutex to modify cgroups.
1400 * Any task can increment and decrement the count field without lock.
1401 * So in general, code holding cgroup_mutex can't rely on the count
1402 * field not changing. However, if the count goes to zero, then only
1403 * cgroup_attach_task() can increment it again. Because a count of zero
1404 * means that no tasks are currently attached, therefore there is no
1405 * way a task attached to that cgroup can fork (the other way to
1406 * increment the count). So code holding cgroup_mutex can safely
1407 * assume that if the count is zero, it will stay zero. Similarly, if
1408 * a task holds cgroup_mutex on a cgroup with zero count, it
1409 * knows that the cgroup won't be removed, as cgroup_rmdir()
1412 * A cgroup can only be deleted if both its 'count' of using tasks
1413 * is zero, and its list of 'children' cgroups is empty. Since all
1414 * tasks in the system use _some_ cgroup, and since there is always at
1415 * least one task in the system (init, pid == 1), therefore, root cgroup
1416 * always has either children cgroups and/or using tasks. So we don't
1417 * need a special hack to ensure that root cgroup cannot be deleted.
1419 * P.S. One more locking exception. RCU is used to guard the
1420 * update of a tasks cgroup pointer by cgroup_attach_task()
1423 static struct kernfs_syscall_ops cgroup_kf_syscall_ops
;
1425 static char *cgroup_file_name(struct cgroup
*cgrp
, const struct cftype
*cft
,
1428 struct cgroup_subsys
*ss
= cft
->ss
;
1430 if (cft
->ss
&& !(cft
->flags
& CFTYPE_NO_PREFIX
) &&
1431 !(cgrp
->root
->flags
& CGRP_ROOT_NOPREFIX
))
1432 snprintf(buf
, CGROUP_FILE_NAME_MAX
, "%s.%s",
1433 cgroup_on_dfl(cgrp
) ? ss
->name
: ss
->legacy_name
,
1436 strscpy(buf
, cft
->name
, CGROUP_FILE_NAME_MAX
);
1441 * cgroup_file_mode - deduce file mode of a control file
1442 * @cft: the control file in question
1444 * S_IRUGO for read, S_IWUSR for write.
1446 static umode_t
cgroup_file_mode(const struct cftype
*cft
)
1450 if (cft
->read_u64
|| cft
->read_s64
|| cft
->seq_show
)
1453 if (cft
->write_u64
|| cft
->write_s64
|| cft
->write
) {
1454 if (cft
->flags
& CFTYPE_WORLD_WRITABLE
)
1464 * cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask
1465 * @subtree_control: the new subtree_control mask to consider
1466 * @this_ss_mask: available subsystems
1468 * On the default hierarchy, a subsystem may request other subsystems to be
1469 * enabled together through its ->depends_on mask. In such cases, more
1470 * subsystems than specified in "cgroup.subtree_control" may be enabled.
1472 * This function calculates which subsystems need to be enabled if
1473 * @subtree_control is to be applied while restricted to @this_ss_mask.
1475 static u16
cgroup_calc_subtree_ss_mask(u16 subtree_control
, u16 this_ss_mask
)
1477 u16 cur_ss_mask
= subtree_control
;
1478 struct cgroup_subsys
*ss
;
1481 lockdep_assert_held(&cgroup_mutex
);
1483 cur_ss_mask
|= cgrp_dfl_implicit_ss_mask
;
1486 u16 new_ss_mask
= cur_ss_mask
;
1488 do_each_subsys_mask(ss
, ssid
, cur_ss_mask
) {
1489 new_ss_mask
|= ss
->depends_on
;
1490 } while_each_subsys_mask();
1493 * Mask out subsystems which aren't available. This can
1494 * happen only if some depended-upon subsystems were bound
1495 * to non-default hierarchies.
1497 new_ss_mask
&= this_ss_mask
;
1499 if (new_ss_mask
== cur_ss_mask
)
1501 cur_ss_mask
= new_ss_mask
;
1508 * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods
1509 * @kn: the kernfs_node being serviced
1511 * This helper undoes cgroup_kn_lock_live() and should be invoked before
1512 * the method finishes if locking succeeded. Note that once this function
1513 * returns the cgroup returned by cgroup_kn_lock_live() may become
1514 * inaccessible any time. If the caller intends to continue to access the
1515 * cgroup, it should pin it before invoking this function.
1517 void cgroup_kn_unlock(struct kernfs_node
*kn
)
1519 struct cgroup
*cgrp
;
1521 if (kernfs_type(kn
) == KERNFS_DIR
)
1524 cgrp
= kn
->parent
->priv
;
1526 mutex_unlock(&cgroup_mutex
);
1528 kernfs_unbreak_active_protection(kn
);
1533 * cgroup_kn_lock_live - locking helper for cgroup kernfs methods
1534 * @kn: the kernfs_node being serviced
1535 * @drain_offline: perform offline draining on the cgroup
1537 * This helper is to be used by a cgroup kernfs method currently servicing
1538 * @kn. It breaks the active protection, performs cgroup locking and
1539 * verifies that the associated cgroup is alive. Returns the cgroup if
1540 * alive; otherwise, %NULL. A successful return should be undone by a
1541 * matching cgroup_kn_unlock() invocation. If @drain_offline is %true, the
1542 * cgroup is drained of offlining csses before return.
1544 * Any cgroup kernfs method implementation which requires locking the
1545 * associated cgroup should use this helper. It avoids nesting cgroup
1546 * locking under kernfs active protection and allows all kernfs operations
1547 * including self-removal.
1549 struct cgroup
*cgroup_kn_lock_live(struct kernfs_node
*kn
, bool drain_offline
)
1551 struct cgroup
*cgrp
;
1553 if (kernfs_type(kn
) == KERNFS_DIR
)
1556 cgrp
= kn
->parent
->priv
;
1559 * We're gonna grab cgroup_mutex which nests outside kernfs
1560 * active_ref. cgroup liveliness check alone provides enough
1561 * protection against removal. Ensure @cgrp stays accessible and
1562 * break the active_ref protection.
1564 if (!cgroup_tryget(cgrp
))
1566 kernfs_break_active_protection(kn
);
1569 cgroup_lock_and_drain_offline(cgrp
);
1571 mutex_lock(&cgroup_mutex
);
1573 if (!cgroup_is_dead(cgrp
))
1576 cgroup_kn_unlock(kn
);
1580 static void cgroup_rm_file(struct cgroup
*cgrp
, const struct cftype
*cft
)
1582 char name
[CGROUP_FILE_NAME_MAX
];
1584 lockdep_assert_held(&cgroup_mutex
);
1586 if (cft
->file_offset
) {
1587 struct cgroup_subsys_state
*css
= cgroup_css(cgrp
, cft
->ss
);
1588 struct cgroup_file
*cfile
= (void *)css
+ cft
->file_offset
;
1590 spin_lock_irq(&cgroup_file_kn_lock
);
1592 spin_unlock_irq(&cgroup_file_kn_lock
);
1594 del_timer_sync(&cfile
->notify_timer
);
1597 kernfs_remove_by_name(cgrp
->kn
, cgroup_file_name(cgrp
, cft
, name
));
1601 * css_clear_dir - remove subsys files in a cgroup directory
1604 static void css_clear_dir(struct cgroup_subsys_state
*css
)
1606 struct cgroup
*cgrp
= css
->cgroup
;
1607 struct cftype
*cfts
;
1609 if (!(css
->flags
& CSS_VISIBLE
))
1612 css
->flags
&= ~CSS_VISIBLE
;
1615 if (cgroup_on_dfl(cgrp
))
1616 cfts
= cgroup_base_files
;
1618 cfts
= cgroup1_base_files
;
1620 cgroup_addrm_files(css
, cgrp
, cfts
, false);
1622 list_for_each_entry(cfts
, &css
->ss
->cfts
, node
)
1623 cgroup_addrm_files(css
, cgrp
, cfts
, false);
1628 * css_populate_dir - create subsys files in a cgroup directory
1631 * On failure, no file is added.
1633 static int css_populate_dir(struct cgroup_subsys_state
*css
)
1635 struct cgroup
*cgrp
= css
->cgroup
;
1636 struct cftype
*cfts
, *failed_cfts
;
1639 if ((css
->flags
& CSS_VISIBLE
) || !cgrp
->kn
)
1643 if (cgroup_on_dfl(cgrp
))
1644 cfts
= cgroup_base_files
;
1646 cfts
= cgroup1_base_files
;
1648 ret
= cgroup_addrm_files(&cgrp
->self
, cgrp
, cfts
, true);
1652 list_for_each_entry(cfts
, &css
->ss
->cfts
, node
) {
1653 ret
= cgroup_addrm_files(css
, cgrp
, cfts
, true);
1661 css
->flags
|= CSS_VISIBLE
;
1665 list_for_each_entry(cfts
, &css
->ss
->cfts
, node
) {
1666 if (cfts
== failed_cfts
)
1668 cgroup_addrm_files(css
, cgrp
, cfts
, false);
1673 int rebind_subsystems(struct cgroup_root
*dst_root
, u16 ss_mask
)
1675 struct cgroup
*dcgrp
= &dst_root
->cgrp
;
1676 struct cgroup_subsys
*ss
;
1679 lockdep_assert_held(&cgroup_mutex
);
1681 do_each_subsys_mask(ss
, ssid
, ss_mask
) {
1683 * If @ss has non-root csses attached to it, can't move.
1684 * If @ss is an implicit controller, it is exempt from this
1685 * rule and can be stolen.
1687 if (css_next_child(NULL
, cgroup_css(&ss
->root
->cgrp
, ss
)) &&
1688 !ss
->implicit_on_dfl
)
1691 /* can't move between two non-dummy roots either */
1692 if (ss
->root
!= &cgrp_dfl_root
&& dst_root
!= &cgrp_dfl_root
)
1694 } while_each_subsys_mask();
1696 do_each_subsys_mask(ss
, ssid
, ss_mask
) {
1697 struct cgroup_root
*src_root
= ss
->root
;
1698 struct cgroup
*scgrp
= &src_root
->cgrp
;
1699 struct cgroup_subsys_state
*css
= cgroup_css(scgrp
, ss
);
1700 struct css_set
*cset
;
1702 WARN_ON(!css
|| cgroup_css(dcgrp
, ss
));
1704 /* disable from the source */
1705 src_root
->subsys_mask
&= ~(1 << ssid
);
1706 WARN_ON(cgroup_apply_control(scgrp
));
1707 cgroup_finalize_control(scgrp
, 0);
1710 RCU_INIT_POINTER(scgrp
->subsys
[ssid
], NULL
);
1711 rcu_assign_pointer(dcgrp
->subsys
[ssid
], css
);
1712 ss
->root
= dst_root
;
1713 css
->cgroup
= dcgrp
;
1715 spin_lock_irq(&css_set_lock
);
1716 hash_for_each(css_set_table
, i
, cset
, hlist
)
1717 list_move_tail(&cset
->e_cset_node
[ss
->id
],
1718 &dcgrp
->e_csets
[ss
->id
]);
1719 spin_unlock_irq(&css_set_lock
);
1721 /* default hierarchy doesn't enable controllers by default */
1722 dst_root
->subsys_mask
|= 1 << ssid
;
1723 if (dst_root
== &cgrp_dfl_root
) {
1724 static_branch_enable(cgroup_subsys_on_dfl_key
[ssid
]);
1726 dcgrp
->subtree_control
|= 1 << ssid
;
1727 static_branch_disable(cgroup_subsys_on_dfl_key
[ssid
]);
1730 ret
= cgroup_apply_control(dcgrp
);
1732 pr_warn("partial failure to rebind %s controller (err=%d)\n",
1737 } while_each_subsys_mask();
1739 kernfs_activate(dcgrp
->kn
);
1743 int cgroup_show_path(struct seq_file
*sf
, struct kernfs_node
*kf_node
,
1744 struct kernfs_root
*kf_root
)
1748 struct cgroup_root
*kf_cgroot
= cgroup_root_from_kf(kf_root
);
1749 struct cgroup
*ns_cgroup
;
1751 buf
= kmalloc(PATH_MAX
, GFP_KERNEL
);
1755 spin_lock_irq(&css_set_lock
);
1756 ns_cgroup
= current_cgns_cgroup_from_root(kf_cgroot
);
1757 len
= kernfs_path_from_node(kf_node
, ns_cgroup
->kn
, buf
, PATH_MAX
);
1758 spin_unlock_irq(&css_set_lock
);
1760 if (len
>= PATH_MAX
)
1763 seq_escape(sf
, buf
, " \t\n\\");
1770 static int parse_cgroup_root_flags(char *data
, unsigned int *root_flags
)
1779 while ((token
= strsep(&data
, ",")) != NULL
) {
1780 if (!strcmp(token
, "nsdelegate")) {
1781 *root_flags
|= CGRP_ROOT_NS_DELEGATE
;
1785 pr_err("cgroup2: unknown option \"%s\"\n", token
);
1792 static void apply_cgroup_root_flags(unsigned int root_flags
)
1794 if (current
->nsproxy
->cgroup_ns
== &init_cgroup_ns
) {
1795 if (root_flags
& CGRP_ROOT_NS_DELEGATE
)
1796 cgrp_dfl_root
.flags
|= CGRP_ROOT_NS_DELEGATE
;
1798 cgrp_dfl_root
.flags
&= ~CGRP_ROOT_NS_DELEGATE
;
1802 static int cgroup_show_options(struct seq_file
*seq
, struct kernfs_root
*kf_root
)
1804 if (cgrp_dfl_root
.flags
& CGRP_ROOT_NS_DELEGATE
)
1805 seq_puts(seq
, ",nsdelegate");
1809 static int cgroup_remount(struct kernfs_root
*kf_root
, int *flags
, char *data
)
1811 unsigned int root_flags
;
1814 ret
= parse_cgroup_root_flags(data
, &root_flags
);
1818 apply_cgroup_root_flags(root_flags
);
1823 * To reduce the fork() overhead for systems that are not actually using
1824 * their cgroups capability, we don't maintain the lists running through
1825 * each css_set to its tasks until we see the list actually used - in other
1826 * words after the first mount.
1828 static bool use_task_css_set_links __read_mostly
;
1830 static void cgroup_enable_task_cg_lists(void)
1832 struct task_struct
*p
, *g
;
1835 * We need tasklist_lock because RCU is not safe against
1836 * while_each_thread(). Besides, a forking task that has passed
1837 * cgroup_post_fork() without seeing use_task_css_set_links = 1
1838 * is not guaranteed to have its child immediately visible in the
1839 * tasklist if we walk through it with RCU.
1841 read_lock(&tasklist_lock
);
1842 spin_lock_irq(&css_set_lock
);
1844 if (use_task_css_set_links
)
1847 use_task_css_set_links
= true;
1849 do_each_thread(g
, p
) {
1850 WARN_ON_ONCE(!list_empty(&p
->cg_list
) ||
1851 task_css_set(p
) != &init_css_set
);
1854 * We should check if the process is exiting, otherwise
1855 * it will race with cgroup_exit() in that the list
1856 * entry won't be deleted though the process has exited.
1857 * Do it while holding siglock so that we don't end up
1858 * racing against cgroup_exit().
1860 * Interrupts were already disabled while acquiring
1861 * the css_set_lock, so we do not need to disable it
1862 * again when acquiring the sighand->siglock here.
1864 spin_lock(&p
->sighand
->siglock
);
1865 if (!(p
->flags
& PF_EXITING
)) {
1866 struct css_set
*cset
= task_css_set(p
);
1868 if (!css_set_populated(cset
))
1869 css_set_update_populated(cset
, true);
1870 list_add_tail(&p
->cg_list
, &cset
->tasks
);
1874 spin_unlock(&p
->sighand
->siglock
);
1875 } while_each_thread(g
, p
);
1877 spin_unlock_irq(&css_set_lock
);
1878 read_unlock(&tasklist_lock
);
1881 static void init_cgroup_housekeeping(struct cgroup
*cgrp
)
1883 struct cgroup_subsys
*ss
;
1886 INIT_LIST_HEAD(&cgrp
->self
.sibling
);
1887 INIT_LIST_HEAD(&cgrp
->self
.children
);
1888 INIT_LIST_HEAD(&cgrp
->cset_links
);
1889 INIT_LIST_HEAD(&cgrp
->pidlists
);
1890 mutex_init(&cgrp
->pidlist_mutex
);
1891 cgrp
->self
.cgroup
= cgrp
;
1892 cgrp
->self
.flags
|= CSS_ONLINE
;
1893 cgrp
->dom_cgrp
= cgrp
;
1894 cgrp
->max_descendants
= INT_MAX
;
1895 cgrp
->max_depth
= INT_MAX
;
1896 INIT_LIST_HEAD(&cgrp
->rstat_css_list
);
1897 prev_cputime_init(&cgrp
->prev_cputime
);
1899 for_each_subsys(ss
, ssid
)
1900 INIT_LIST_HEAD(&cgrp
->e_csets
[ssid
]);
1902 init_waitqueue_head(&cgrp
->offline_waitq
);
1903 INIT_WORK(&cgrp
->release_agent_work
, cgroup1_release_agent
);
1906 void init_cgroup_root(struct cgroup_root
*root
, struct cgroup_sb_opts
*opts
)
1908 struct cgroup
*cgrp
= &root
->cgrp
;
1910 INIT_LIST_HEAD(&root
->root_list
);
1911 atomic_set(&root
->nr_cgrps
, 1);
1913 init_cgroup_housekeeping(cgrp
);
1914 idr_init(&root
->cgroup_idr
);
1916 root
->flags
= opts
->flags
;
1917 if (opts
->release_agent
)
1918 strscpy(root
->release_agent_path
, opts
->release_agent
, PATH_MAX
);
1920 strscpy(root
->name
, opts
->name
, MAX_CGROUP_ROOT_NAMELEN
);
1921 if (opts
->cpuset_clone_children
)
1922 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &root
->cgrp
.flags
);
1925 int cgroup_setup_root(struct cgroup_root
*root
, u16 ss_mask
, int ref_flags
)
1927 LIST_HEAD(tmp_links
);
1928 struct cgroup
*root_cgrp
= &root
->cgrp
;
1929 struct kernfs_syscall_ops
*kf_sops
;
1930 struct css_set
*cset
;
1933 lockdep_assert_held(&cgroup_mutex
);
1935 ret
= cgroup_idr_alloc(&root
->cgroup_idr
, root_cgrp
, 1, 2, GFP_KERNEL
);
1938 root_cgrp
->id
= ret
;
1939 root_cgrp
->ancestor_ids
[0] = ret
;
1941 ret
= percpu_ref_init(&root_cgrp
->self
.refcnt
, css_release
,
1942 ref_flags
, GFP_KERNEL
);
1947 * We're accessing css_set_count without locking css_set_lock here,
1948 * but that's OK - it can only be increased by someone holding
1949 * cgroup_lock, and that's us. Later rebinding may disable
1950 * controllers on the default hierarchy and thus create new csets,
1951 * which can't be more than the existing ones. Allocate 2x.
1953 ret
= allocate_cgrp_cset_links(2 * css_set_count
, &tmp_links
);
1957 ret
= cgroup_init_root_id(root
);
1961 kf_sops
= root
== &cgrp_dfl_root
?
1962 &cgroup_kf_syscall_ops
: &cgroup1_kf_syscall_ops
;
1964 root
->kf_root
= kernfs_create_root(kf_sops
,
1965 KERNFS_ROOT_CREATE_DEACTIVATED
|
1966 KERNFS_ROOT_SUPPORT_EXPORTOP
,
1968 if (IS_ERR(root
->kf_root
)) {
1969 ret
= PTR_ERR(root
->kf_root
);
1972 root_cgrp
->kn
= root
->kf_root
->kn
;
1974 ret
= css_populate_dir(&root_cgrp
->self
);
1978 ret
= rebind_subsystems(root
, ss_mask
);
1982 ret
= cgroup_bpf_inherit(root_cgrp
);
1985 trace_cgroup_setup_root(root
);
1988 * There must be no failure case after here, since rebinding takes
1989 * care of subsystems' refcounts, which are explicitly dropped in
1990 * the failure exit path.
1992 list_add(&root
->root_list
, &cgroup_roots
);
1993 cgroup_root_count
++;
1996 * Link the root cgroup in this hierarchy into all the css_set
1999 spin_lock_irq(&css_set_lock
);
2000 hash_for_each(css_set_table
, i
, cset
, hlist
) {
2001 link_css_set(&tmp_links
, cset
, root_cgrp
);
2002 if (css_set_populated(cset
))
2003 cgroup_update_populated(root_cgrp
, true);
2005 spin_unlock_irq(&css_set_lock
);
2007 BUG_ON(!list_empty(&root_cgrp
->self
.children
));
2008 BUG_ON(atomic_read(&root
->nr_cgrps
) != 1);
2010 kernfs_activate(root_cgrp
->kn
);
2015 kernfs_destroy_root(root
->kf_root
);
2016 root
->kf_root
= NULL
;
2018 cgroup_exit_root_id(root
);
2020 percpu_ref_exit(&root_cgrp
->self
.refcnt
);
2022 free_cgrp_cset_links(&tmp_links
);
2026 struct dentry
*cgroup_do_mount(struct file_system_type
*fs_type
, int flags
,
2027 struct cgroup_root
*root
, unsigned long magic
,
2028 struct cgroup_namespace
*ns
)
2030 struct dentry
*dentry
;
2033 dentry
= kernfs_mount(fs_type
, flags
, root
->kf_root
, magic
, &new_sb
);
2036 * In non-init cgroup namespace, instead of root cgroup's dentry,
2037 * we return the dentry corresponding to the cgroupns->root_cgrp.
2039 if (!IS_ERR(dentry
) && ns
!= &init_cgroup_ns
) {
2040 struct dentry
*nsdentry
;
2041 struct cgroup
*cgrp
;
2043 mutex_lock(&cgroup_mutex
);
2044 spin_lock_irq(&css_set_lock
);
2046 cgrp
= cset_cgroup_from_root(ns
->root_cset
, root
);
2048 spin_unlock_irq(&css_set_lock
);
2049 mutex_unlock(&cgroup_mutex
);
2051 nsdentry
= kernfs_node_dentry(cgrp
->kn
, dentry
->d_sb
);
2056 if (IS_ERR(dentry
) || !new_sb
)
2057 cgroup_put(&root
->cgrp
);
2062 static struct dentry
*cgroup_mount(struct file_system_type
*fs_type
,
2063 int flags
, const char *unused_dev_name
,
2066 struct cgroup_namespace
*ns
= current
->nsproxy
->cgroup_ns
;
2067 struct dentry
*dentry
;
2072 /* Check if the caller has permission to mount. */
2073 if (!ns_capable(ns
->user_ns
, CAP_SYS_ADMIN
)) {
2075 return ERR_PTR(-EPERM
);
2079 * The first time anyone tries to mount a cgroup, enable the list
2080 * linking each css_set to its tasks and fix up all existing tasks.
2082 if (!use_task_css_set_links
)
2083 cgroup_enable_task_cg_lists();
2085 if (fs_type
== &cgroup2_fs_type
) {
2086 unsigned int root_flags
;
2088 ret
= parse_cgroup_root_flags(data
, &root_flags
);
2091 return ERR_PTR(ret
);
2094 cgrp_dfl_visible
= true;
2095 cgroup_get_live(&cgrp_dfl_root
.cgrp
);
2097 dentry
= cgroup_do_mount(&cgroup2_fs_type
, flags
, &cgrp_dfl_root
,
2098 CGROUP2_SUPER_MAGIC
, ns
);
2099 if (!IS_ERR(dentry
))
2100 apply_cgroup_root_flags(root_flags
);
2102 dentry
= cgroup1_mount(&cgroup_fs_type
, flags
, data
,
2103 CGROUP_SUPER_MAGIC
, ns
);
2110 static void cgroup_kill_sb(struct super_block
*sb
)
2112 struct kernfs_root
*kf_root
= kernfs_root_from_sb(sb
);
2113 struct cgroup_root
*root
= cgroup_root_from_kf(kf_root
);
2116 * If @root doesn't have any mounts or children, start killing it.
2117 * This prevents new mounts by disabling percpu_ref_tryget_live().
2118 * cgroup_mount() may wait for @root's release.
2120 * And don't kill the default root.
2122 if (!list_empty(&root
->cgrp
.self
.children
) ||
2123 root
== &cgrp_dfl_root
)
2124 cgroup_put(&root
->cgrp
);
2126 percpu_ref_kill(&root
->cgrp
.self
.refcnt
);
2131 struct file_system_type cgroup_fs_type
= {
2133 .mount
= cgroup_mount
,
2134 .kill_sb
= cgroup_kill_sb
,
2135 .fs_flags
= FS_USERNS_MOUNT
,
2138 static struct file_system_type cgroup2_fs_type
= {
2140 .mount
= cgroup_mount
,
2141 .kill_sb
= cgroup_kill_sb
,
2142 .fs_flags
= FS_USERNS_MOUNT
,
2145 int cgroup_path_ns_locked(struct cgroup
*cgrp
, char *buf
, size_t buflen
,
2146 struct cgroup_namespace
*ns
)
2148 struct cgroup
*root
= cset_cgroup_from_root(ns
->root_cset
, cgrp
->root
);
2150 return kernfs_path_from_node(cgrp
->kn
, root
->kn
, buf
, buflen
);
2153 int cgroup_path_ns(struct cgroup
*cgrp
, char *buf
, size_t buflen
,
2154 struct cgroup_namespace
*ns
)
2158 mutex_lock(&cgroup_mutex
);
2159 spin_lock_irq(&css_set_lock
);
2161 ret
= cgroup_path_ns_locked(cgrp
, buf
, buflen
, ns
);
2163 spin_unlock_irq(&css_set_lock
);
2164 mutex_unlock(&cgroup_mutex
);
2168 EXPORT_SYMBOL_GPL(cgroup_path_ns
);
2171 * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
2172 * @task: target task
2173 * @buf: the buffer to write the path into
2174 * @buflen: the length of the buffer
2176 * Determine @task's cgroup on the first (the one with the lowest non-zero
2177 * hierarchy_id) cgroup hierarchy and copy its path into @buf. This
2178 * function grabs cgroup_mutex and shouldn't be used inside locks used by
2179 * cgroup controller callbacks.
2181 * Return value is the same as kernfs_path().
2183 int task_cgroup_path(struct task_struct
*task
, char *buf
, size_t buflen
)
2185 struct cgroup_root
*root
;
2186 struct cgroup
*cgrp
;
2187 int hierarchy_id
= 1;
2190 mutex_lock(&cgroup_mutex
);
2191 spin_lock_irq(&css_set_lock
);
2193 root
= idr_get_next(&cgroup_hierarchy_idr
, &hierarchy_id
);
2196 cgrp
= task_cgroup_from_root(task
, root
);
2197 ret
= cgroup_path_ns_locked(cgrp
, buf
, buflen
, &init_cgroup_ns
);
2199 /* if no hierarchy exists, everyone is in "/" */
2200 ret
= strlcpy(buf
, "/", buflen
);
2203 spin_unlock_irq(&css_set_lock
);
2204 mutex_unlock(&cgroup_mutex
);
2207 EXPORT_SYMBOL_GPL(task_cgroup_path
);
2210 * cgroup_migrate_add_task - add a migration target task to a migration context
2211 * @task: target task
2212 * @mgctx: target migration context
2214 * Add @task, which is a migration target, to @mgctx->tset. This function
2215 * becomes noop if @task doesn't need to be migrated. @task's css_set
2216 * should have been added as a migration source and @task->cg_list will be
2217 * moved from the css_set's tasks list to mg_tasks one.
2219 static void cgroup_migrate_add_task(struct task_struct
*task
,
2220 struct cgroup_mgctx
*mgctx
)
2222 struct css_set
*cset
;
2224 lockdep_assert_held(&css_set_lock
);
2226 /* @task either already exited or can't exit until the end */
2227 if (task
->flags
& PF_EXITING
)
2230 /* leave @task alone if post_fork() hasn't linked it yet */
2231 if (list_empty(&task
->cg_list
))
2234 cset
= task_css_set(task
);
2235 if (!cset
->mg_src_cgrp
)
2238 mgctx
->tset
.nr_tasks
++;
2240 list_move_tail(&task
->cg_list
, &cset
->mg_tasks
);
2241 if (list_empty(&cset
->mg_node
))
2242 list_add_tail(&cset
->mg_node
,
2243 &mgctx
->tset
.src_csets
);
2244 if (list_empty(&cset
->mg_dst_cset
->mg_node
))
2245 list_add_tail(&cset
->mg_dst_cset
->mg_node
,
2246 &mgctx
->tset
.dst_csets
);
2250 * cgroup_taskset_first - reset taskset and return the first task
2251 * @tset: taskset of interest
2252 * @dst_cssp: output variable for the destination css
2254 * @tset iteration is initialized and the first task is returned.
2256 struct task_struct
*cgroup_taskset_first(struct cgroup_taskset
*tset
,
2257 struct cgroup_subsys_state
**dst_cssp
)
2259 tset
->cur_cset
= list_first_entry(tset
->csets
, struct css_set
, mg_node
);
2260 tset
->cur_task
= NULL
;
2262 return cgroup_taskset_next(tset
, dst_cssp
);
2266 * cgroup_taskset_next - iterate to the next task in taskset
2267 * @tset: taskset of interest
2268 * @dst_cssp: output variable for the destination css
2270 * Return the next task in @tset. Iteration must have been initialized
2271 * with cgroup_taskset_first().
2273 struct task_struct
*cgroup_taskset_next(struct cgroup_taskset
*tset
,
2274 struct cgroup_subsys_state
**dst_cssp
)
2276 struct css_set
*cset
= tset
->cur_cset
;
2277 struct task_struct
*task
= tset
->cur_task
;
2279 while (&cset
->mg_node
!= tset
->csets
) {
2281 task
= list_first_entry(&cset
->mg_tasks
,
2282 struct task_struct
, cg_list
);
2284 task
= list_next_entry(task
, cg_list
);
2286 if (&task
->cg_list
!= &cset
->mg_tasks
) {
2287 tset
->cur_cset
= cset
;
2288 tset
->cur_task
= task
;
2291 * This function may be called both before and
2292 * after cgroup_taskset_migrate(). The two cases
2293 * can be distinguished by looking at whether @cset
2294 * has its ->mg_dst_cset set.
2296 if (cset
->mg_dst_cset
)
2297 *dst_cssp
= cset
->mg_dst_cset
->subsys
[tset
->ssid
];
2299 *dst_cssp
= cset
->subsys
[tset
->ssid
];
2304 cset
= list_next_entry(cset
, mg_node
);
2312 * cgroup_taskset_migrate - migrate a taskset
2313 * @mgctx: migration context
2315 * Migrate tasks in @mgctx as setup by migration preparation functions.
2316 * This function fails iff one of the ->can_attach callbacks fails and
2317 * guarantees that either all or none of the tasks in @mgctx are migrated.
2318 * @mgctx is consumed regardless of success.
2320 static int cgroup_migrate_execute(struct cgroup_mgctx
*mgctx
)
2322 struct cgroup_taskset
*tset
= &mgctx
->tset
;
2323 struct cgroup_subsys
*ss
;
2324 struct task_struct
*task
, *tmp_task
;
2325 struct css_set
*cset
, *tmp_cset
;
2326 int ssid
, failed_ssid
, ret
;
2328 /* check that we can legitimately attach to the cgroup */
2329 if (tset
->nr_tasks
) {
2330 do_each_subsys_mask(ss
, ssid
, mgctx
->ss_mask
) {
2331 if (ss
->can_attach
) {
2333 ret
= ss
->can_attach(tset
);
2336 goto out_cancel_attach
;
2339 } while_each_subsys_mask();
2343 * Now that we're guaranteed success, proceed to move all tasks to
2344 * the new cgroup. There are no failure cases after here, so this
2345 * is the commit point.
2347 spin_lock_irq(&css_set_lock
);
2348 list_for_each_entry(cset
, &tset
->src_csets
, mg_node
) {
2349 list_for_each_entry_safe(task
, tmp_task
, &cset
->mg_tasks
, cg_list
) {
2350 struct css_set
*from_cset
= task_css_set(task
);
2351 struct css_set
*to_cset
= cset
->mg_dst_cset
;
2353 get_css_set(to_cset
);
2354 to_cset
->nr_tasks
++;
2355 css_set_move_task(task
, from_cset
, to_cset
, true);
2356 put_css_set_locked(from_cset
);
2357 from_cset
->nr_tasks
--;
2360 spin_unlock_irq(&css_set_lock
);
2363 * Migration is committed, all target tasks are now on dst_csets.
2364 * Nothing is sensitive to fork() after this point. Notify
2365 * controllers that migration is complete.
2367 tset
->csets
= &tset
->dst_csets
;
2369 if (tset
->nr_tasks
) {
2370 do_each_subsys_mask(ss
, ssid
, mgctx
->ss_mask
) {
2375 } while_each_subsys_mask();
2379 goto out_release_tset
;
2382 if (tset
->nr_tasks
) {
2383 do_each_subsys_mask(ss
, ssid
, mgctx
->ss_mask
) {
2384 if (ssid
== failed_ssid
)
2386 if (ss
->cancel_attach
) {
2388 ss
->cancel_attach(tset
);
2390 } while_each_subsys_mask();
2393 spin_lock_irq(&css_set_lock
);
2394 list_splice_init(&tset
->dst_csets
, &tset
->src_csets
);
2395 list_for_each_entry_safe(cset
, tmp_cset
, &tset
->src_csets
, mg_node
) {
2396 list_splice_tail_init(&cset
->mg_tasks
, &cset
->tasks
);
2397 list_del_init(&cset
->mg_node
);
2399 spin_unlock_irq(&css_set_lock
);
2402 * Re-initialize the cgroup_taskset structure in case it is reused
2403 * again in another cgroup_migrate_add_task()/cgroup_migrate_execute()
2407 tset
->csets
= &tset
->src_csets
;
2412 * cgroup_migrate_vet_dst - verify whether a cgroup can be migration destination
2413 * @dst_cgrp: destination cgroup to test
2415 * On the default hierarchy, except for the mixable, (possible) thread root
2416 * and threaded cgroups, subtree_control must be zero for migration
2417 * destination cgroups with tasks so that child cgroups don't compete
2420 int cgroup_migrate_vet_dst(struct cgroup
*dst_cgrp
)
2422 /* v1 doesn't have any restriction */
2423 if (!cgroup_on_dfl(dst_cgrp
))
2426 /* verify @dst_cgrp can host resources */
2427 if (!cgroup_is_valid_domain(dst_cgrp
->dom_cgrp
))
2430 /* mixables don't care */
2431 if (cgroup_is_mixable(dst_cgrp
))
2435 * If @dst_cgrp is already or can become a thread root or is
2436 * threaded, it doesn't matter.
2438 if (cgroup_can_be_thread_root(dst_cgrp
) || cgroup_is_threaded(dst_cgrp
))
2441 /* apply no-internal-process constraint */
2442 if (dst_cgrp
->subtree_control
)
2449 * cgroup_migrate_finish - cleanup after attach
2450 * @mgctx: migration context
2452 * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See
2453 * those functions for details.
2455 void cgroup_migrate_finish(struct cgroup_mgctx
*mgctx
)
2457 LIST_HEAD(preloaded
);
2458 struct css_set
*cset
, *tmp_cset
;
2460 lockdep_assert_held(&cgroup_mutex
);
2462 spin_lock_irq(&css_set_lock
);
2464 list_splice_tail_init(&mgctx
->preloaded_src_csets
, &preloaded
);
2465 list_splice_tail_init(&mgctx
->preloaded_dst_csets
, &preloaded
);
2467 list_for_each_entry_safe(cset
, tmp_cset
, &preloaded
, mg_preload_node
) {
2468 cset
->mg_src_cgrp
= NULL
;
2469 cset
->mg_dst_cgrp
= NULL
;
2470 cset
->mg_dst_cset
= NULL
;
2471 list_del_init(&cset
->mg_preload_node
);
2472 put_css_set_locked(cset
);
2475 spin_unlock_irq(&css_set_lock
);
2479 * cgroup_migrate_add_src - add a migration source css_set
2480 * @src_cset: the source css_set to add
2481 * @dst_cgrp: the destination cgroup
2482 * @mgctx: migration context
2484 * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin
2485 * @src_cset and add it to @mgctx->src_csets, which should later be cleaned
2486 * up by cgroup_migrate_finish().
2488 * This function may be called without holding cgroup_threadgroup_rwsem
2489 * even if the target is a process. Threads may be created and destroyed
2490 * but as long as cgroup_mutex is not dropped, no new css_set can be put
2491 * into play and the preloaded css_sets are guaranteed to cover all
2494 void cgroup_migrate_add_src(struct css_set
*src_cset
,
2495 struct cgroup
*dst_cgrp
,
2496 struct cgroup_mgctx
*mgctx
)
2498 struct cgroup
*src_cgrp
;
2500 lockdep_assert_held(&cgroup_mutex
);
2501 lockdep_assert_held(&css_set_lock
);
2504 * If ->dead, @src_set is associated with one or more dead cgroups
2505 * and doesn't contain any migratable tasks. Ignore it early so
2506 * that the rest of migration path doesn't get confused by it.
2511 src_cgrp
= cset_cgroup_from_root(src_cset
, dst_cgrp
->root
);
2513 if (!list_empty(&src_cset
->mg_preload_node
))
2516 WARN_ON(src_cset
->mg_src_cgrp
);
2517 WARN_ON(src_cset
->mg_dst_cgrp
);
2518 WARN_ON(!list_empty(&src_cset
->mg_tasks
));
2519 WARN_ON(!list_empty(&src_cset
->mg_node
));
2521 src_cset
->mg_src_cgrp
= src_cgrp
;
2522 src_cset
->mg_dst_cgrp
= dst_cgrp
;
2523 get_css_set(src_cset
);
2524 list_add_tail(&src_cset
->mg_preload_node
, &mgctx
->preloaded_src_csets
);
2528 * cgroup_migrate_prepare_dst - prepare destination css_sets for migration
2529 * @mgctx: migration context
2531 * Tasks are about to be moved and all the source css_sets have been
2532 * preloaded to @mgctx->preloaded_src_csets. This function looks up and
2533 * pins all destination css_sets, links each to its source, and append them
2534 * to @mgctx->preloaded_dst_csets.
2536 * This function must be called after cgroup_migrate_add_src() has been
2537 * called on each migration source css_set. After migration is performed
2538 * using cgroup_migrate(), cgroup_migrate_finish() must be called on
2541 int cgroup_migrate_prepare_dst(struct cgroup_mgctx
*mgctx
)
2543 struct css_set
*src_cset
, *tmp_cset
;
2545 lockdep_assert_held(&cgroup_mutex
);
2547 /* look up the dst cset for each src cset and link it to src */
2548 list_for_each_entry_safe(src_cset
, tmp_cset
, &mgctx
->preloaded_src_csets
,
2550 struct css_set
*dst_cset
;
2551 struct cgroup_subsys
*ss
;
2554 dst_cset
= find_css_set(src_cset
, src_cset
->mg_dst_cgrp
);
2558 WARN_ON_ONCE(src_cset
->mg_dst_cset
|| dst_cset
->mg_dst_cset
);
2561 * If src cset equals dst, it's noop. Drop the src.
2562 * cgroup_migrate() will skip the cset too. Note that we
2563 * can't handle src == dst as some nodes are used by both.
2565 if (src_cset
== dst_cset
) {
2566 src_cset
->mg_src_cgrp
= NULL
;
2567 src_cset
->mg_dst_cgrp
= NULL
;
2568 list_del_init(&src_cset
->mg_preload_node
);
2569 put_css_set(src_cset
);
2570 put_css_set(dst_cset
);
2574 src_cset
->mg_dst_cset
= dst_cset
;
2576 if (list_empty(&dst_cset
->mg_preload_node
))
2577 list_add_tail(&dst_cset
->mg_preload_node
,
2578 &mgctx
->preloaded_dst_csets
);
2580 put_css_set(dst_cset
);
2582 for_each_subsys(ss
, ssid
)
2583 if (src_cset
->subsys
[ssid
] != dst_cset
->subsys
[ssid
])
2584 mgctx
->ss_mask
|= 1 << ssid
;
2589 cgroup_migrate_finish(mgctx
);
2594 * cgroup_migrate - migrate a process or task to a cgroup
2595 * @leader: the leader of the process or the task to migrate
2596 * @threadgroup: whether @leader points to the whole process or a single task
2597 * @mgctx: migration context
2599 * Migrate a process or task denoted by @leader. If migrating a process,
2600 * the caller must be holding cgroup_threadgroup_rwsem. The caller is also
2601 * responsible for invoking cgroup_migrate_add_src() and
2602 * cgroup_migrate_prepare_dst() on the targets before invoking this
2603 * function and following up with cgroup_migrate_finish().
2605 * As long as a controller's ->can_attach() doesn't fail, this function is
2606 * guaranteed to succeed. This means that, excluding ->can_attach()
2607 * failure, when migrating multiple targets, the success or failure can be
2608 * decided for all targets by invoking group_migrate_prepare_dst() before
2609 * actually starting migrating.
2611 int cgroup_migrate(struct task_struct
*leader
, bool threadgroup
,
2612 struct cgroup_mgctx
*mgctx
)
2614 struct task_struct
*task
;
2617 * Prevent freeing of tasks while we take a snapshot. Tasks that are
2618 * already PF_EXITING could be freed from underneath us unless we
2619 * take an rcu_read_lock.
2621 spin_lock_irq(&css_set_lock
);
2625 cgroup_migrate_add_task(task
, mgctx
);
2628 } while_each_thread(leader
, task
);
2630 spin_unlock_irq(&css_set_lock
);
2632 return cgroup_migrate_execute(mgctx
);
2636 * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
2637 * @dst_cgrp: the cgroup to attach to
2638 * @leader: the task or the leader of the threadgroup to be attached
2639 * @threadgroup: attach the whole threadgroup?
2641 * Call holding cgroup_mutex and cgroup_threadgroup_rwsem.
2643 int cgroup_attach_task(struct cgroup
*dst_cgrp
, struct task_struct
*leader
,
2646 DEFINE_CGROUP_MGCTX(mgctx
);
2647 struct task_struct
*task
;
2650 ret
= cgroup_migrate_vet_dst(dst_cgrp
);
2654 /* look up all src csets */
2655 spin_lock_irq(&css_set_lock
);
2659 cgroup_migrate_add_src(task_css_set(task
), dst_cgrp
, &mgctx
);
2662 } while_each_thread(leader
, task
);
2664 spin_unlock_irq(&css_set_lock
);
2666 /* prepare dst csets and commit */
2667 ret
= cgroup_migrate_prepare_dst(&mgctx
);
2669 ret
= cgroup_migrate(leader
, threadgroup
, &mgctx
);
2671 cgroup_migrate_finish(&mgctx
);
2674 TRACE_CGROUP_PATH(attach_task
, dst_cgrp
, leader
, threadgroup
);
2679 struct task_struct
*cgroup_procs_write_start(char *buf
, bool threadgroup
)
2680 __acquires(&cgroup_threadgroup_rwsem
)
2682 struct task_struct
*tsk
;
2685 if (kstrtoint(strstrip(buf
), 0, &pid
) || pid
< 0)
2686 return ERR_PTR(-EINVAL
);
2688 percpu_down_write(&cgroup_threadgroup_rwsem
);
2692 tsk
= find_task_by_vpid(pid
);
2694 tsk
= ERR_PTR(-ESRCH
);
2695 goto out_unlock_threadgroup
;
2702 tsk
= tsk
->group_leader
;
2705 * kthreads may acquire PF_NO_SETAFFINITY during initialization.
2706 * If userland migrates such a kthread to a non-root cgroup, it can
2707 * become trapped in a cpuset, or RT kthread may be born in a
2708 * cgroup with no rt_runtime allocated. Just say no.
2710 if (tsk
->no_cgroup_migration
|| (tsk
->flags
& PF_NO_SETAFFINITY
)) {
2711 tsk
= ERR_PTR(-EINVAL
);
2712 goto out_unlock_threadgroup
;
2715 get_task_struct(tsk
);
2716 goto out_unlock_rcu
;
2718 out_unlock_threadgroup
:
2719 percpu_up_write(&cgroup_threadgroup_rwsem
);
2725 void cgroup_procs_write_finish(struct task_struct
*task
)
2726 __releases(&cgroup_threadgroup_rwsem
)
2728 struct cgroup_subsys
*ss
;
2731 /* release reference from cgroup_procs_write_start() */
2732 put_task_struct(task
);
2734 percpu_up_write(&cgroup_threadgroup_rwsem
);
2735 for_each_subsys(ss
, ssid
)
2736 if (ss
->post_attach
)
2740 static void cgroup_print_ss_mask(struct seq_file
*seq
, u16 ss_mask
)
2742 struct cgroup_subsys
*ss
;
2743 bool printed
= false;
2746 do_each_subsys_mask(ss
, ssid
, ss_mask
) {
2749 seq_printf(seq
, "%s", ss
->name
);
2751 } while_each_subsys_mask();
2753 seq_putc(seq
, '\n');
2756 /* show controllers which are enabled from the parent */
2757 static int cgroup_controllers_show(struct seq_file
*seq
, void *v
)
2759 struct cgroup
*cgrp
= seq_css(seq
)->cgroup
;
2761 cgroup_print_ss_mask(seq
, cgroup_control(cgrp
));
2765 /* show controllers which are enabled for a given cgroup's children */
2766 static int cgroup_subtree_control_show(struct seq_file
*seq
, void *v
)
2768 struct cgroup
*cgrp
= seq_css(seq
)->cgroup
;
2770 cgroup_print_ss_mask(seq
, cgrp
->subtree_control
);
2775 * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy
2776 * @cgrp: root of the subtree to update csses for
2778 * @cgrp's control masks have changed and its subtree's css associations
2779 * need to be updated accordingly. This function looks up all css_sets
2780 * which are attached to the subtree, creates the matching updated css_sets
2781 * and migrates the tasks to the new ones.
2783 static int cgroup_update_dfl_csses(struct cgroup
*cgrp
)
2785 DEFINE_CGROUP_MGCTX(mgctx
);
2786 struct cgroup_subsys_state
*d_css
;
2787 struct cgroup
*dsct
;
2788 struct css_set
*src_cset
;
2791 lockdep_assert_held(&cgroup_mutex
);
2793 percpu_down_write(&cgroup_threadgroup_rwsem
);
2795 /* look up all csses currently attached to @cgrp's subtree */
2796 spin_lock_irq(&css_set_lock
);
2797 cgroup_for_each_live_descendant_pre(dsct
, d_css
, cgrp
) {
2798 struct cgrp_cset_link
*link
;
2800 list_for_each_entry(link
, &dsct
->cset_links
, cset_link
)
2801 cgroup_migrate_add_src(link
->cset
, dsct
, &mgctx
);
2803 spin_unlock_irq(&css_set_lock
);
2805 /* NULL dst indicates self on default hierarchy */
2806 ret
= cgroup_migrate_prepare_dst(&mgctx
);
2810 spin_lock_irq(&css_set_lock
);
2811 list_for_each_entry(src_cset
, &mgctx
.preloaded_src_csets
, mg_preload_node
) {
2812 struct task_struct
*task
, *ntask
;
2814 /* all tasks in src_csets need to be migrated */
2815 list_for_each_entry_safe(task
, ntask
, &src_cset
->tasks
, cg_list
)
2816 cgroup_migrate_add_task(task
, &mgctx
);
2818 spin_unlock_irq(&css_set_lock
);
2820 ret
= cgroup_migrate_execute(&mgctx
);
2822 cgroup_migrate_finish(&mgctx
);
2823 percpu_up_write(&cgroup_threadgroup_rwsem
);
2828 * cgroup_lock_and_drain_offline - lock cgroup_mutex and drain offlined csses
2829 * @cgrp: root of the target subtree
2831 * Because css offlining is asynchronous, userland may try to re-enable a
2832 * controller while the previous css is still around. This function grabs
2833 * cgroup_mutex and drains the previous css instances of @cgrp's subtree.
2835 void cgroup_lock_and_drain_offline(struct cgroup
*cgrp
)
2836 __acquires(&cgroup_mutex
)
2838 struct cgroup
*dsct
;
2839 struct cgroup_subsys_state
*d_css
;
2840 struct cgroup_subsys
*ss
;
2844 mutex_lock(&cgroup_mutex
);
2846 cgroup_for_each_live_descendant_post(dsct
, d_css
, cgrp
) {
2847 for_each_subsys(ss
, ssid
) {
2848 struct cgroup_subsys_state
*css
= cgroup_css(dsct
, ss
);
2851 if (!css
|| !percpu_ref_is_dying(&css
->refcnt
))
2854 cgroup_get_live(dsct
);
2855 prepare_to_wait(&dsct
->offline_waitq
, &wait
,
2856 TASK_UNINTERRUPTIBLE
);
2858 mutex_unlock(&cgroup_mutex
);
2860 finish_wait(&dsct
->offline_waitq
, &wait
);
2869 * cgroup_save_control - save control masks and dom_cgrp of a subtree
2870 * @cgrp: root of the target subtree
2872 * Save ->subtree_control, ->subtree_ss_mask and ->dom_cgrp to the
2873 * respective old_ prefixed fields for @cgrp's subtree including @cgrp
2876 static void cgroup_save_control(struct cgroup
*cgrp
)
2878 struct cgroup
*dsct
;
2879 struct cgroup_subsys_state
*d_css
;
2881 cgroup_for_each_live_descendant_pre(dsct
, d_css
, cgrp
) {
2882 dsct
->old_subtree_control
= dsct
->subtree_control
;
2883 dsct
->old_subtree_ss_mask
= dsct
->subtree_ss_mask
;
2884 dsct
->old_dom_cgrp
= dsct
->dom_cgrp
;
2889 * cgroup_propagate_control - refresh control masks of a subtree
2890 * @cgrp: root of the target subtree
2892 * For @cgrp and its subtree, ensure ->subtree_ss_mask matches
2893 * ->subtree_control and propagate controller availability through the
2894 * subtree so that descendants don't have unavailable controllers enabled.
2896 static void cgroup_propagate_control(struct cgroup
*cgrp
)
2898 struct cgroup
*dsct
;
2899 struct cgroup_subsys_state
*d_css
;
2901 cgroup_for_each_live_descendant_pre(dsct
, d_css
, cgrp
) {
2902 dsct
->subtree_control
&= cgroup_control(dsct
);
2903 dsct
->subtree_ss_mask
=
2904 cgroup_calc_subtree_ss_mask(dsct
->subtree_control
,
2905 cgroup_ss_mask(dsct
));
2910 * cgroup_restore_control - restore control masks and dom_cgrp of a subtree
2911 * @cgrp: root of the target subtree
2913 * Restore ->subtree_control, ->subtree_ss_mask and ->dom_cgrp from the
2914 * respective old_ prefixed fields for @cgrp's subtree including @cgrp
2917 static void cgroup_restore_control(struct cgroup
*cgrp
)
2919 struct cgroup
*dsct
;
2920 struct cgroup_subsys_state
*d_css
;
2922 cgroup_for_each_live_descendant_post(dsct
, d_css
, cgrp
) {
2923 dsct
->subtree_control
= dsct
->old_subtree_control
;
2924 dsct
->subtree_ss_mask
= dsct
->old_subtree_ss_mask
;
2925 dsct
->dom_cgrp
= dsct
->old_dom_cgrp
;
2929 static bool css_visible(struct cgroup_subsys_state
*css
)
2931 struct cgroup_subsys
*ss
= css
->ss
;
2932 struct cgroup
*cgrp
= css
->cgroup
;
2934 if (cgroup_control(cgrp
) & (1 << ss
->id
))
2936 if (!(cgroup_ss_mask(cgrp
) & (1 << ss
->id
)))
2938 return cgroup_on_dfl(cgrp
) && ss
->implicit_on_dfl
;
2942 * cgroup_apply_control_enable - enable or show csses according to control
2943 * @cgrp: root of the target subtree
2945 * Walk @cgrp's subtree and create new csses or make the existing ones
2946 * visible. A css is created invisible if it's being implicitly enabled
2947 * through dependency. An invisible css is made visible when the userland
2948 * explicitly enables it.
2950 * Returns 0 on success, -errno on failure. On failure, csses which have
2951 * been processed already aren't cleaned up. The caller is responsible for
2952 * cleaning up with cgroup_apply_control_disable().
2954 static int cgroup_apply_control_enable(struct cgroup
*cgrp
)
2956 struct cgroup
*dsct
;
2957 struct cgroup_subsys_state
*d_css
;
2958 struct cgroup_subsys
*ss
;
2961 cgroup_for_each_live_descendant_pre(dsct
, d_css
, cgrp
) {
2962 for_each_subsys(ss
, ssid
) {
2963 struct cgroup_subsys_state
*css
= cgroup_css(dsct
, ss
);
2965 WARN_ON_ONCE(css
&& percpu_ref_is_dying(&css
->refcnt
));
2967 if (!(cgroup_ss_mask(dsct
) & (1 << ss
->id
)))
2971 css
= css_create(dsct
, ss
);
2973 return PTR_ERR(css
);
2976 if (css_visible(css
)) {
2977 ret
= css_populate_dir(css
);
2988 * cgroup_apply_control_disable - kill or hide csses according to control
2989 * @cgrp: root of the target subtree
2991 * Walk @cgrp's subtree and kill and hide csses so that they match
2992 * cgroup_ss_mask() and cgroup_visible_mask().
2994 * A css is hidden when the userland requests it to be disabled while other
2995 * subsystems are still depending on it. The css must not actively control
2996 * resources and be in the vanilla state if it's made visible again later.
2997 * Controllers which may be depended upon should provide ->css_reset() for
3000 static void cgroup_apply_control_disable(struct cgroup
*cgrp
)
3002 struct cgroup
*dsct
;
3003 struct cgroup_subsys_state
*d_css
;
3004 struct cgroup_subsys
*ss
;
3007 cgroup_for_each_live_descendant_post(dsct
, d_css
, cgrp
) {
3008 for_each_subsys(ss
, ssid
) {
3009 struct cgroup_subsys_state
*css
= cgroup_css(dsct
, ss
);
3011 WARN_ON_ONCE(css
&& percpu_ref_is_dying(&css
->refcnt
));
3017 !(cgroup_ss_mask(dsct
) & (1 << ss
->id
))) {
3019 } else if (!css_visible(css
)) {
3029 * cgroup_apply_control - apply control mask updates to the subtree
3030 * @cgrp: root of the target subtree
3032 * subsystems can be enabled and disabled in a subtree using the following
3035 * 1. Call cgroup_save_control() to stash the current state.
3036 * 2. Update ->subtree_control masks in the subtree as desired.
3037 * 3. Call cgroup_apply_control() to apply the changes.
3038 * 4. Optionally perform other related operations.
3039 * 5. Call cgroup_finalize_control() to finish up.
3041 * This function implements step 3 and propagates the mask changes
3042 * throughout @cgrp's subtree, updates csses accordingly and perform
3043 * process migrations.
3045 static int cgroup_apply_control(struct cgroup
*cgrp
)
3049 cgroup_propagate_control(cgrp
);
3051 ret
= cgroup_apply_control_enable(cgrp
);
3056 * At this point, cgroup_e_css_by_mask() results reflect the new csses
3057 * making the following cgroup_update_dfl_csses() properly update
3058 * css associations of all tasks in the subtree.
3060 ret
= cgroup_update_dfl_csses(cgrp
);
3068 * cgroup_finalize_control - finalize control mask update
3069 * @cgrp: root of the target subtree
3070 * @ret: the result of the update
3072 * Finalize control mask update. See cgroup_apply_control() for more info.
3074 static void cgroup_finalize_control(struct cgroup
*cgrp
, int ret
)
3077 cgroup_restore_control(cgrp
);
3078 cgroup_propagate_control(cgrp
);
3081 cgroup_apply_control_disable(cgrp
);
3084 static int cgroup_vet_subtree_control_enable(struct cgroup
*cgrp
, u16 enable
)
3086 u16 domain_enable
= enable
& ~cgrp_dfl_threaded_ss_mask
;
3088 /* if nothing is getting enabled, nothing to worry about */
3092 /* can @cgrp host any resources? */
3093 if (!cgroup_is_valid_domain(cgrp
->dom_cgrp
))
3096 /* mixables don't care */
3097 if (cgroup_is_mixable(cgrp
))
3100 if (domain_enable
) {
3101 /* can't enable domain controllers inside a thread subtree */
3102 if (cgroup_is_thread_root(cgrp
) || cgroup_is_threaded(cgrp
))
3106 * Threaded controllers can handle internal competitions
3107 * and are always allowed inside a (prospective) thread
3110 if (cgroup_can_be_thread_root(cgrp
) || cgroup_is_threaded(cgrp
))
3115 * Controllers can't be enabled for a cgroup with tasks to avoid
3116 * child cgroups competing against tasks.
3118 if (cgroup_has_tasks(cgrp
))
3124 /* change the enabled child controllers for a cgroup in the default hierarchy */
3125 static ssize_t
cgroup_subtree_control_write(struct kernfs_open_file
*of
,
3126 char *buf
, size_t nbytes
,
3129 u16 enable
= 0, disable
= 0;
3130 struct cgroup
*cgrp
, *child
;
3131 struct cgroup_subsys
*ss
;
3136 * Parse input - space separated list of subsystem names prefixed
3137 * with either + or -.
3139 buf
= strstrip(buf
);
3140 while ((tok
= strsep(&buf
, " "))) {
3143 do_each_subsys_mask(ss
, ssid
, ~cgrp_dfl_inhibit_ss_mask
) {
3144 if (!cgroup_ssid_enabled(ssid
) ||
3145 strcmp(tok
+ 1, ss
->name
))
3149 enable
|= 1 << ssid
;
3150 disable
&= ~(1 << ssid
);
3151 } else if (*tok
== '-') {
3152 disable
|= 1 << ssid
;
3153 enable
&= ~(1 << ssid
);
3158 } while_each_subsys_mask();
3159 if (ssid
== CGROUP_SUBSYS_COUNT
)
3163 cgrp
= cgroup_kn_lock_live(of
->kn
, true);
3167 for_each_subsys(ss
, ssid
) {
3168 if (enable
& (1 << ssid
)) {
3169 if (cgrp
->subtree_control
& (1 << ssid
)) {
3170 enable
&= ~(1 << ssid
);
3174 if (!(cgroup_control(cgrp
) & (1 << ssid
))) {
3178 } else if (disable
& (1 << ssid
)) {
3179 if (!(cgrp
->subtree_control
& (1 << ssid
))) {
3180 disable
&= ~(1 << ssid
);
3184 /* a child has it enabled? */
3185 cgroup_for_each_live_child(child
, cgrp
) {
3186 if (child
->subtree_control
& (1 << ssid
)) {
3194 if (!enable
&& !disable
) {
3199 ret
= cgroup_vet_subtree_control_enable(cgrp
, enable
);
3203 /* save and update control masks and prepare csses */
3204 cgroup_save_control(cgrp
);
3206 cgrp
->subtree_control
|= enable
;
3207 cgrp
->subtree_control
&= ~disable
;
3209 ret
= cgroup_apply_control(cgrp
);
3210 cgroup_finalize_control(cgrp
, ret
);
3214 kernfs_activate(cgrp
->kn
);
3216 cgroup_kn_unlock(of
->kn
);
3217 return ret
?: nbytes
;
3221 * cgroup_enable_threaded - make @cgrp threaded
3222 * @cgrp: the target cgroup
3224 * Called when "threaded" is written to the cgroup.type interface file and
3225 * tries to make @cgrp threaded and join the parent's resource domain.
3226 * This function is never called on the root cgroup as cgroup.type doesn't
3229 static int cgroup_enable_threaded(struct cgroup
*cgrp
)
3231 struct cgroup
*parent
= cgroup_parent(cgrp
);
3232 struct cgroup
*dom_cgrp
= parent
->dom_cgrp
;
3233 struct cgroup
*dsct
;
3234 struct cgroup_subsys_state
*d_css
;
3237 lockdep_assert_held(&cgroup_mutex
);
3239 /* noop if already threaded */
3240 if (cgroup_is_threaded(cgrp
))
3244 * If @cgroup is populated or has domain controllers enabled, it
3245 * can't be switched. While the below cgroup_can_be_thread_root()
3246 * test can catch the same conditions, that's only when @parent is
3247 * not mixable, so let's check it explicitly.
3249 if (cgroup_is_populated(cgrp
) ||
3250 cgrp
->subtree_control
& ~cgrp_dfl_threaded_ss_mask
)
3253 /* we're joining the parent's domain, ensure its validity */
3254 if (!cgroup_is_valid_domain(dom_cgrp
) ||
3255 !cgroup_can_be_thread_root(dom_cgrp
))
3259 * The following shouldn't cause actual migrations and should
3262 cgroup_save_control(cgrp
);
3264 cgroup_for_each_live_descendant_pre(dsct
, d_css
, cgrp
)
3265 if (dsct
== cgrp
|| cgroup_is_threaded(dsct
))
3266 dsct
->dom_cgrp
= dom_cgrp
;
3268 ret
= cgroup_apply_control(cgrp
);
3270 parent
->nr_threaded_children
++;
3272 cgroup_finalize_control(cgrp
, ret
);
3276 static int cgroup_type_show(struct seq_file
*seq
, void *v
)
3278 struct cgroup
*cgrp
= seq_css(seq
)->cgroup
;
3280 if (cgroup_is_threaded(cgrp
))
3281 seq_puts(seq
, "threaded\n");
3282 else if (!cgroup_is_valid_domain(cgrp
))
3283 seq_puts(seq
, "domain invalid\n");
3284 else if (cgroup_is_thread_root(cgrp
))
3285 seq_puts(seq
, "domain threaded\n");
3287 seq_puts(seq
, "domain\n");
3292 static ssize_t
cgroup_type_write(struct kernfs_open_file
*of
, char *buf
,
3293 size_t nbytes
, loff_t off
)
3295 struct cgroup
*cgrp
;
3298 /* only switching to threaded mode is supported */
3299 if (strcmp(strstrip(buf
), "threaded"))
3302 cgrp
= cgroup_kn_lock_live(of
->kn
, false);
3306 /* threaded can only be enabled */
3307 ret
= cgroup_enable_threaded(cgrp
);
3309 cgroup_kn_unlock(of
->kn
);
3310 return ret
?: nbytes
;
3313 static int cgroup_max_descendants_show(struct seq_file
*seq
, void *v
)
3315 struct cgroup
*cgrp
= seq_css(seq
)->cgroup
;
3316 int descendants
= READ_ONCE(cgrp
->max_descendants
);
3318 if (descendants
== INT_MAX
)
3319 seq_puts(seq
, "max\n");
3321 seq_printf(seq
, "%d\n", descendants
);
3326 static ssize_t
cgroup_max_descendants_write(struct kernfs_open_file
*of
,
3327 char *buf
, size_t nbytes
, loff_t off
)
3329 struct cgroup
*cgrp
;
3333 buf
= strstrip(buf
);
3334 if (!strcmp(buf
, "max")) {
3335 descendants
= INT_MAX
;
3337 ret
= kstrtoint(buf
, 0, &descendants
);
3342 if (descendants
< 0)
3345 cgrp
= cgroup_kn_lock_live(of
->kn
, false);
3349 cgrp
->max_descendants
= descendants
;
3351 cgroup_kn_unlock(of
->kn
);
3356 static int cgroup_max_depth_show(struct seq_file
*seq
, void *v
)
3358 struct cgroup
*cgrp
= seq_css(seq
)->cgroup
;
3359 int depth
= READ_ONCE(cgrp
->max_depth
);
3361 if (depth
== INT_MAX
)
3362 seq_puts(seq
, "max\n");
3364 seq_printf(seq
, "%d\n", depth
);
3369 static ssize_t
cgroup_max_depth_write(struct kernfs_open_file
*of
,
3370 char *buf
, size_t nbytes
, loff_t off
)
3372 struct cgroup
*cgrp
;
3376 buf
= strstrip(buf
);
3377 if (!strcmp(buf
, "max")) {
3380 ret
= kstrtoint(buf
, 0, &depth
);
3388 cgrp
= cgroup_kn_lock_live(of
->kn
, false);
3392 cgrp
->max_depth
= depth
;
3394 cgroup_kn_unlock(of
->kn
);
3399 static int cgroup_events_show(struct seq_file
*seq
, void *v
)
3401 seq_printf(seq
, "populated %d\n",
3402 cgroup_is_populated(seq_css(seq
)->cgroup
));
3406 static int cgroup_stat_show(struct seq_file
*seq
, void *v
)
3408 struct cgroup
*cgroup
= seq_css(seq
)->cgroup
;
3410 seq_printf(seq
, "nr_descendants %d\n",
3411 cgroup
->nr_descendants
);
3412 seq_printf(seq
, "nr_dying_descendants %d\n",
3413 cgroup
->nr_dying_descendants
);
3418 static int __maybe_unused
cgroup_extra_stat_show(struct seq_file
*seq
,
3419 struct cgroup
*cgrp
, int ssid
)
3421 struct cgroup_subsys
*ss
= cgroup_subsys
[ssid
];
3422 struct cgroup_subsys_state
*css
;
3425 if (!ss
->css_extra_stat_show
)
3428 css
= cgroup_tryget_css(cgrp
, ss
);
3432 ret
= ss
->css_extra_stat_show(seq
, css
);
3437 static int cpu_stat_show(struct seq_file
*seq
, void *v
)
3439 struct cgroup __maybe_unused
*cgrp
= seq_css(seq
)->cgroup
;
3442 cgroup_base_stat_cputime_show(seq
);
3443 #ifdef CONFIG_CGROUP_SCHED
3444 ret
= cgroup_extra_stat_show(seq
, cgrp
, cpu_cgrp_id
);
3449 static int cgroup_file_open(struct kernfs_open_file
*of
)
3451 struct cftype
*cft
= of
->kn
->priv
;
3454 return cft
->open(of
);
3458 static void cgroup_file_release(struct kernfs_open_file
*of
)
3460 struct cftype
*cft
= of
->kn
->priv
;
3466 static ssize_t
cgroup_file_write(struct kernfs_open_file
*of
, char *buf
,
3467 size_t nbytes
, loff_t off
)
3469 struct cgroup_namespace
*ns
= current
->nsproxy
->cgroup_ns
;
3470 struct cgroup
*cgrp
= of
->kn
->parent
->priv
;
3471 struct cftype
*cft
= of
->kn
->priv
;
3472 struct cgroup_subsys_state
*css
;
3476 * If namespaces are delegation boundaries, disallow writes to
3477 * files in an non-init namespace root from inside the namespace
3478 * except for the files explicitly marked delegatable -
3479 * cgroup.procs and cgroup.subtree_control.
3481 if ((cgrp
->root
->flags
& CGRP_ROOT_NS_DELEGATE
) &&
3482 !(cft
->flags
& CFTYPE_NS_DELEGATABLE
) &&
3483 ns
!= &init_cgroup_ns
&& ns
->root_cset
->dfl_cgrp
== cgrp
)
3487 return cft
->write(of
, buf
, nbytes
, off
);
3490 * kernfs guarantees that a file isn't deleted with operations in
3491 * flight, which means that the matching css is and stays alive and
3492 * doesn't need to be pinned. The RCU locking is not necessary
3493 * either. It's just for the convenience of using cgroup_css().
3496 css
= cgroup_css(cgrp
, cft
->ss
);
3499 if (cft
->write_u64
) {
3500 unsigned long long v
;
3501 ret
= kstrtoull(buf
, 0, &v
);
3503 ret
= cft
->write_u64(css
, cft
, v
);
3504 } else if (cft
->write_s64
) {
3506 ret
= kstrtoll(buf
, 0, &v
);
3508 ret
= cft
->write_s64(css
, cft
, v
);
3513 return ret
?: nbytes
;
3516 static void *cgroup_seqfile_start(struct seq_file
*seq
, loff_t
*ppos
)
3518 return seq_cft(seq
)->seq_start(seq
, ppos
);
3521 static void *cgroup_seqfile_next(struct seq_file
*seq
, void *v
, loff_t
*ppos
)
3523 return seq_cft(seq
)->seq_next(seq
, v
, ppos
);
3526 static void cgroup_seqfile_stop(struct seq_file
*seq
, void *v
)
3528 if (seq_cft(seq
)->seq_stop
)
3529 seq_cft(seq
)->seq_stop(seq
, v
);
3532 static int cgroup_seqfile_show(struct seq_file
*m
, void *arg
)
3534 struct cftype
*cft
= seq_cft(m
);
3535 struct cgroup_subsys_state
*css
= seq_css(m
);
3538 return cft
->seq_show(m
, arg
);
3541 seq_printf(m
, "%llu\n", cft
->read_u64(css
, cft
));
3542 else if (cft
->read_s64
)
3543 seq_printf(m
, "%lld\n", cft
->read_s64(css
, cft
));
3549 static struct kernfs_ops cgroup_kf_single_ops
= {
3550 .atomic_write_len
= PAGE_SIZE
,
3551 .open
= cgroup_file_open
,
3552 .release
= cgroup_file_release
,
3553 .write
= cgroup_file_write
,
3554 .seq_show
= cgroup_seqfile_show
,
3557 static struct kernfs_ops cgroup_kf_ops
= {
3558 .atomic_write_len
= PAGE_SIZE
,
3559 .open
= cgroup_file_open
,
3560 .release
= cgroup_file_release
,
3561 .write
= cgroup_file_write
,
3562 .seq_start
= cgroup_seqfile_start
,
3563 .seq_next
= cgroup_seqfile_next
,
3564 .seq_stop
= cgroup_seqfile_stop
,
3565 .seq_show
= cgroup_seqfile_show
,
3568 /* set uid and gid of cgroup dirs and files to that of the creator */
3569 static int cgroup_kn_set_ugid(struct kernfs_node
*kn
)
3571 struct iattr iattr
= { .ia_valid
= ATTR_UID
| ATTR_GID
,
3572 .ia_uid
= current_fsuid(),
3573 .ia_gid
= current_fsgid(), };
3575 if (uid_eq(iattr
.ia_uid
, GLOBAL_ROOT_UID
) &&
3576 gid_eq(iattr
.ia_gid
, GLOBAL_ROOT_GID
))
3579 return kernfs_setattr(kn
, &iattr
);
3582 static void cgroup_file_notify_timer(struct timer_list
*timer
)
3584 cgroup_file_notify(container_of(timer
, struct cgroup_file
,
3588 static int cgroup_add_file(struct cgroup_subsys_state
*css
, struct cgroup
*cgrp
,
3591 char name
[CGROUP_FILE_NAME_MAX
];
3592 struct kernfs_node
*kn
;
3593 struct lock_class_key
*key
= NULL
;
3596 #ifdef CONFIG_DEBUG_LOCK_ALLOC
3597 key
= &cft
->lockdep_key
;
3599 kn
= __kernfs_create_file(cgrp
->kn
, cgroup_file_name(cgrp
, cft
, name
),
3600 cgroup_file_mode(cft
),
3601 GLOBAL_ROOT_UID
, GLOBAL_ROOT_GID
,
3602 0, cft
->kf_ops
, cft
,
3607 ret
= cgroup_kn_set_ugid(kn
);
3613 if (cft
->file_offset
) {
3614 struct cgroup_file
*cfile
= (void *)css
+ cft
->file_offset
;
3616 timer_setup(&cfile
->notify_timer
, cgroup_file_notify_timer
, 0);
3618 spin_lock_irq(&cgroup_file_kn_lock
);
3620 spin_unlock_irq(&cgroup_file_kn_lock
);
3627 * cgroup_addrm_files - add or remove files to a cgroup directory
3628 * @css: the target css
3629 * @cgrp: the target cgroup (usually css->cgroup)
3630 * @cfts: array of cftypes to be added
3631 * @is_add: whether to add or remove
3633 * Depending on @is_add, add or remove files defined by @cfts on @cgrp.
3634 * For removals, this function never fails.
3636 static int cgroup_addrm_files(struct cgroup_subsys_state
*css
,
3637 struct cgroup
*cgrp
, struct cftype cfts
[],
3640 struct cftype
*cft
, *cft_end
= NULL
;
3643 lockdep_assert_held(&cgroup_mutex
);
3646 for (cft
= cfts
; cft
!= cft_end
&& cft
->name
[0] != '\0'; cft
++) {
3647 /* does cft->flags tell us to skip this file on @cgrp? */
3648 if ((cft
->flags
& __CFTYPE_ONLY_ON_DFL
) && !cgroup_on_dfl(cgrp
))
3650 if ((cft
->flags
& __CFTYPE_NOT_ON_DFL
) && cgroup_on_dfl(cgrp
))
3652 if ((cft
->flags
& CFTYPE_NOT_ON_ROOT
) && !cgroup_parent(cgrp
))
3654 if ((cft
->flags
& CFTYPE_ONLY_ON_ROOT
) && cgroup_parent(cgrp
))
3658 ret
= cgroup_add_file(css
, cgrp
, cft
);
3660 pr_warn("%s: failed to add %s, err=%d\n",
3661 __func__
, cft
->name
, ret
);
3667 cgroup_rm_file(cgrp
, cft
);
3673 static int cgroup_apply_cftypes(struct cftype
*cfts
, bool is_add
)
3675 struct cgroup_subsys
*ss
= cfts
[0].ss
;
3676 struct cgroup
*root
= &ss
->root
->cgrp
;
3677 struct cgroup_subsys_state
*css
;
3680 lockdep_assert_held(&cgroup_mutex
);
3682 /* add/rm files for all cgroups created before */
3683 css_for_each_descendant_pre(css
, cgroup_css(root
, ss
)) {
3684 struct cgroup
*cgrp
= css
->cgroup
;
3686 if (!(css
->flags
& CSS_VISIBLE
))
3689 ret
= cgroup_addrm_files(css
, cgrp
, cfts
, is_add
);
3695 kernfs_activate(root
->kn
);
3699 static void cgroup_exit_cftypes(struct cftype
*cfts
)
3703 for (cft
= cfts
; cft
->name
[0] != '\0'; cft
++) {
3704 /* free copy for custom atomic_write_len, see init_cftypes() */
3705 if (cft
->max_write_len
&& cft
->max_write_len
!= PAGE_SIZE
)
3710 /* revert flags set by cgroup core while adding @cfts */
3711 cft
->flags
&= ~(__CFTYPE_ONLY_ON_DFL
| __CFTYPE_NOT_ON_DFL
);
3715 static int cgroup_init_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
3719 for (cft
= cfts
; cft
->name
[0] != '\0'; cft
++) {
3720 struct kernfs_ops
*kf_ops
;
3722 WARN_ON(cft
->ss
|| cft
->kf_ops
);
3725 kf_ops
= &cgroup_kf_ops
;
3727 kf_ops
= &cgroup_kf_single_ops
;
3730 * Ugh... if @cft wants a custom max_write_len, we need to
3731 * make a copy of kf_ops to set its atomic_write_len.
3733 if (cft
->max_write_len
&& cft
->max_write_len
!= PAGE_SIZE
) {
3734 kf_ops
= kmemdup(kf_ops
, sizeof(*kf_ops
), GFP_KERNEL
);
3736 cgroup_exit_cftypes(cfts
);
3739 kf_ops
->atomic_write_len
= cft
->max_write_len
;
3742 cft
->kf_ops
= kf_ops
;
3749 static int cgroup_rm_cftypes_locked(struct cftype
*cfts
)
3751 lockdep_assert_held(&cgroup_mutex
);
3753 if (!cfts
|| !cfts
[0].ss
)
3756 list_del(&cfts
->node
);
3757 cgroup_apply_cftypes(cfts
, false);
3758 cgroup_exit_cftypes(cfts
);
3763 * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
3764 * @cfts: zero-length name terminated array of cftypes
3766 * Unregister @cfts. Files described by @cfts are removed from all
3767 * existing cgroups and all future cgroups won't have them either. This
3768 * function can be called anytime whether @cfts' subsys is attached or not.
3770 * Returns 0 on successful unregistration, -ENOENT if @cfts is not
3773 int cgroup_rm_cftypes(struct cftype
*cfts
)
3777 mutex_lock(&cgroup_mutex
);
3778 ret
= cgroup_rm_cftypes_locked(cfts
);
3779 mutex_unlock(&cgroup_mutex
);
3784 * cgroup_add_cftypes - add an array of cftypes to a subsystem
3785 * @ss: target cgroup subsystem
3786 * @cfts: zero-length name terminated array of cftypes
3788 * Register @cfts to @ss. Files described by @cfts are created for all
3789 * existing cgroups to which @ss is attached and all future cgroups will
3790 * have them too. This function can be called anytime whether @ss is
3793 * Returns 0 on successful registration, -errno on failure. Note that this
3794 * function currently returns 0 as long as @cfts registration is successful
3795 * even if some file creation attempts on existing cgroups fail.
3797 static int cgroup_add_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
3801 if (!cgroup_ssid_enabled(ss
->id
))
3804 if (!cfts
|| cfts
[0].name
[0] == '\0')
3807 ret
= cgroup_init_cftypes(ss
, cfts
);
3811 mutex_lock(&cgroup_mutex
);
3813 list_add_tail(&cfts
->node
, &ss
->cfts
);
3814 ret
= cgroup_apply_cftypes(cfts
, true);
3816 cgroup_rm_cftypes_locked(cfts
);
3818 mutex_unlock(&cgroup_mutex
);
3823 * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy
3824 * @ss: target cgroup subsystem
3825 * @cfts: zero-length name terminated array of cftypes
3827 * Similar to cgroup_add_cftypes() but the added files are only used for
3828 * the default hierarchy.
3830 int cgroup_add_dfl_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
3834 for (cft
= cfts
; cft
&& cft
->name
[0] != '\0'; cft
++)
3835 cft
->flags
|= __CFTYPE_ONLY_ON_DFL
;
3836 return cgroup_add_cftypes(ss
, cfts
);
3840 * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies
3841 * @ss: target cgroup subsystem
3842 * @cfts: zero-length name terminated array of cftypes
3844 * Similar to cgroup_add_cftypes() but the added files are only used for
3845 * the legacy hierarchies.
3847 int cgroup_add_legacy_cftypes(struct cgroup_subsys
*ss
, struct cftype
*cfts
)
3851 for (cft
= cfts
; cft
&& cft
->name
[0] != '\0'; cft
++)
3852 cft
->flags
|= __CFTYPE_NOT_ON_DFL
;
3853 return cgroup_add_cftypes(ss
, cfts
);
3857 * cgroup_file_notify - generate a file modified event for a cgroup_file
3858 * @cfile: target cgroup_file
3860 * @cfile must have been obtained by setting cftype->file_offset.
3862 void cgroup_file_notify(struct cgroup_file
*cfile
)
3864 unsigned long flags
;
3866 spin_lock_irqsave(&cgroup_file_kn_lock
, flags
);
3868 unsigned long last
= cfile
->notified_at
;
3869 unsigned long next
= last
+ CGROUP_FILE_NOTIFY_MIN_INTV
;
3871 if (time_in_range(jiffies
, last
, next
)) {
3872 timer_reduce(&cfile
->notify_timer
, next
);
3874 kernfs_notify(cfile
->kn
);
3875 cfile
->notified_at
= jiffies
;
3878 spin_unlock_irqrestore(&cgroup_file_kn_lock
, flags
);
3882 * css_next_child - find the next child of a given css
3883 * @pos: the current position (%NULL to initiate traversal)
3884 * @parent: css whose children to walk
3886 * This function returns the next child of @parent and should be called
3887 * under either cgroup_mutex or RCU read lock. The only requirement is
3888 * that @parent and @pos are accessible. The next sibling is guaranteed to
3889 * be returned regardless of their states.
3891 * If a subsystem synchronizes ->css_online() and the start of iteration, a
3892 * css which finished ->css_online() is guaranteed to be visible in the
3893 * future iterations and will stay visible until the last reference is put.
3894 * A css which hasn't finished ->css_online() or already finished
3895 * ->css_offline() may show up during traversal. It's each subsystem's
3896 * responsibility to synchronize against on/offlining.
3898 struct cgroup_subsys_state
*css_next_child(struct cgroup_subsys_state
*pos
,
3899 struct cgroup_subsys_state
*parent
)
3901 struct cgroup_subsys_state
*next
;
3903 cgroup_assert_mutex_or_rcu_locked();
3906 * @pos could already have been unlinked from the sibling list.
3907 * Once a cgroup is removed, its ->sibling.next is no longer
3908 * updated when its next sibling changes. CSS_RELEASED is set when
3909 * @pos is taken off list, at which time its next pointer is valid,
3910 * and, as releases are serialized, the one pointed to by the next
3911 * pointer is guaranteed to not have started release yet. This
3912 * implies that if we observe !CSS_RELEASED on @pos in this RCU
3913 * critical section, the one pointed to by its next pointer is
3914 * guaranteed to not have finished its RCU grace period even if we
3915 * have dropped rcu_read_lock() inbetween iterations.
3917 * If @pos has CSS_RELEASED set, its next pointer can't be
3918 * dereferenced; however, as each css is given a monotonically
3919 * increasing unique serial number and always appended to the
3920 * sibling list, the next one can be found by walking the parent's
3921 * children until the first css with higher serial number than
3922 * @pos's. While this path can be slower, it happens iff iteration
3923 * races against release and the race window is very small.
3926 next
= list_entry_rcu(parent
->children
.next
, struct cgroup_subsys_state
, sibling
);
3927 } else if (likely(!(pos
->flags
& CSS_RELEASED
))) {
3928 next
= list_entry_rcu(pos
->sibling
.next
, struct cgroup_subsys_state
, sibling
);
3930 list_for_each_entry_rcu(next
, &parent
->children
, sibling
)
3931 if (next
->serial_nr
> pos
->serial_nr
)
3936 * @next, if not pointing to the head, can be dereferenced and is
3939 if (&next
->sibling
!= &parent
->children
)
3945 * css_next_descendant_pre - find the next descendant for pre-order walk
3946 * @pos: the current position (%NULL to initiate traversal)
3947 * @root: css whose descendants to walk
3949 * To be used by css_for_each_descendant_pre(). Find the next descendant
3950 * to visit for pre-order traversal of @root's descendants. @root is
3951 * included in the iteration and the first node to be visited.
3953 * While this function requires cgroup_mutex or RCU read locking, it
3954 * doesn't require the whole traversal to be contained in a single critical
3955 * section. This function will return the correct next descendant as long
3956 * as both @pos and @root are accessible and @pos is a descendant of @root.
3958 * If a subsystem synchronizes ->css_online() and the start of iteration, a
3959 * css which finished ->css_online() is guaranteed to be visible in the
3960 * future iterations and will stay visible until the last reference is put.
3961 * A css which hasn't finished ->css_online() or already finished
3962 * ->css_offline() may show up during traversal. It's each subsystem's
3963 * responsibility to synchronize against on/offlining.
3965 struct cgroup_subsys_state
*
3966 css_next_descendant_pre(struct cgroup_subsys_state
*pos
,
3967 struct cgroup_subsys_state
*root
)
3969 struct cgroup_subsys_state
*next
;
3971 cgroup_assert_mutex_or_rcu_locked();
3973 /* if first iteration, visit @root */
3977 /* visit the first child if exists */
3978 next
= css_next_child(NULL
, pos
);
3982 /* no child, visit my or the closest ancestor's next sibling */
3983 while (pos
!= root
) {
3984 next
= css_next_child(pos
, pos
->parent
);
3994 * css_rightmost_descendant - return the rightmost descendant of a css
3995 * @pos: css of interest
3997 * Return the rightmost descendant of @pos. If there's no descendant, @pos
3998 * is returned. This can be used during pre-order traversal to skip
4001 * While this function requires cgroup_mutex or RCU read locking, it
4002 * doesn't require the whole traversal to be contained in a single critical
4003 * section. This function will return the correct rightmost descendant as
4004 * long as @pos is accessible.
4006 struct cgroup_subsys_state
*
4007 css_rightmost_descendant(struct cgroup_subsys_state
*pos
)
4009 struct cgroup_subsys_state
*last
, *tmp
;
4011 cgroup_assert_mutex_or_rcu_locked();
4015 /* ->prev isn't RCU safe, walk ->next till the end */
4017 css_for_each_child(tmp
, last
)
4024 static struct cgroup_subsys_state
*
4025 css_leftmost_descendant(struct cgroup_subsys_state
*pos
)
4027 struct cgroup_subsys_state
*last
;
4031 pos
= css_next_child(NULL
, pos
);
4038 * css_next_descendant_post - find the next descendant for post-order walk
4039 * @pos: the current position (%NULL to initiate traversal)
4040 * @root: css whose descendants to walk
4042 * To be used by css_for_each_descendant_post(). Find the next descendant
4043 * to visit for post-order traversal of @root's descendants. @root is
4044 * included in the iteration and the last node to be visited.
4046 * While this function requires cgroup_mutex or RCU read locking, it
4047 * doesn't require the whole traversal to be contained in a single critical
4048 * section. This function will return the correct next descendant as long
4049 * as both @pos and @cgroup are accessible and @pos is a descendant of
4052 * If a subsystem synchronizes ->css_online() and the start of iteration, a
4053 * css which finished ->css_online() is guaranteed to be visible in the
4054 * future iterations and will stay visible until the last reference is put.
4055 * A css which hasn't finished ->css_online() or already finished
4056 * ->css_offline() may show up during traversal. It's each subsystem's
4057 * responsibility to synchronize against on/offlining.
4059 struct cgroup_subsys_state
*
4060 css_next_descendant_post(struct cgroup_subsys_state
*pos
,
4061 struct cgroup_subsys_state
*root
)
4063 struct cgroup_subsys_state
*next
;
4065 cgroup_assert_mutex_or_rcu_locked();
4067 /* if first iteration, visit leftmost descendant which may be @root */
4069 return css_leftmost_descendant(root
);
4071 /* if we visited @root, we're done */
4075 /* if there's an unvisited sibling, visit its leftmost descendant */
4076 next
= css_next_child(pos
, pos
->parent
);
4078 return css_leftmost_descendant(next
);
4080 /* no sibling left, visit parent */
4085 * css_has_online_children - does a css have online children
4086 * @css: the target css
4088 * Returns %true if @css has any online children; otherwise, %false. This
4089 * function can be called from any context but the caller is responsible
4090 * for synchronizing against on/offlining as necessary.
4092 bool css_has_online_children(struct cgroup_subsys_state
*css
)
4094 struct cgroup_subsys_state
*child
;
4098 css_for_each_child(child
, css
) {
4099 if (child
->flags
& CSS_ONLINE
) {
4108 static struct css_set
*css_task_iter_next_css_set(struct css_task_iter
*it
)
4110 struct list_head
*l
;
4111 struct cgrp_cset_link
*link
;
4112 struct css_set
*cset
;
4114 lockdep_assert_held(&css_set_lock
);
4116 /* find the next threaded cset */
4117 if (it
->tcset_pos
) {
4118 l
= it
->tcset_pos
->next
;
4120 if (l
!= it
->tcset_head
) {
4122 return container_of(l
, struct css_set
,
4123 threaded_csets_node
);
4126 it
->tcset_pos
= NULL
;
4129 /* find the next cset */
4132 if (l
== it
->cset_head
) {
4133 it
->cset_pos
= NULL
;
4138 cset
= container_of(l
, struct css_set
, e_cset_node
[it
->ss
->id
]);
4140 link
= list_entry(l
, struct cgrp_cset_link
, cset_link
);
4146 /* initialize threaded css_set walking */
4147 if (it
->flags
& CSS_TASK_ITER_THREADED
) {
4149 put_css_set_locked(it
->cur_dcset
);
4150 it
->cur_dcset
= cset
;
4153 it
->tcset_head
= &cset
->threaded_csets
;
4154 it
->tcset_pos
= &cset
->threaded_csets
;
4161 * css_task_iter_advance_css_set - advance a task itererator to the next css_set
4162 * @it: the iterator to advance
4164 * Advance @it to the next css_set to walk.
4166 static void css_task_iter_advance_css_set(struct css_task_iter
*it
)
4168 struct css_set
*cset
;
4170 lockdep_assert_held(&css_set_lock
);
4172 /* Advance to the next non-empty css_set */
4174 cset
= css_task_iter_next_css_set(it
);
4176 it
->task_pos
= NULL
;
4179 } while (!css_set_populated(cset
));
4181 if (!list_empty(&cset
->tasks
))
4182 it
->task_pos
= cset
->tasks
.next
;
4184 it
->task_pos
= cset
->mg_tasks
.next
;
4186 it
->tasks_head
= &cset
->tasks
;
4187 it
->mg_tasks_head
= &cset
->mg_tasks
;
4190 * We don't keep css_sets locked across iteration steps and thus
4191 * need to take steps to ensure that iteration can be resumed after
4192 * the lock is re-acquired. Iteration is performed at two levels -
4193 * css_sets and tasks in them.
4195 * Once created, a css_set never leaves its cgroup lists, so a
4196 * pinned css_set is guaranteed to stay put and we can resume
4197 * iteration afterwards.
4199 * Tasks may leave @cset across iteration steps. This is resolved
4200 * by registering each iterator with the css_set currently being
4201 * walked and making css_set_move_task() advance iterators whose
4202 * next task is leaving.
4205 list_del(&it
->iters_node
);
4206 put_css_set_locked(it
->cur_cset
);
4209 it
->cur_cset
= cset
;
4210 list_add(&it
->iters_node
, &cset
->task_iters
);
4213 static void css_task_iter_advance(struct css_task_iter
*it
)
4215 struct list_head
*next
;
4217 lockdep_assert_held(&css_set_lock
);
4220 * Advance iterator to find next entry. cset->tasks is consumed
4221 * first and then ->mg_tasks. After ->mg_tasks, we move onto the
4224 next
= it
->task_pos
->next
;
4226 if (next
== it
->tasks_head
)
4227 next
= it
->mg_tasks_head
->next
;
4229 if (next
== it
->mg_tasks_head
)
4230 css_task_iter_advance_css_set(it
);
4232 it
->task_pos
= next
;
4234 /* if PROCS, skip over tasks which aren't group leaders */
4235 if ((it
->flags
& CSS_TASK_ITER_PROCS
) && it
->task_pos
&&
4236 !thread_group_leader(list_entry(it
->task_pos
, struct task_struct
,
4242 * css_task_iter_start - initiate task iteration
4243 * @css: the css to walk tasks of
4244 * @flags: CSS_TASK_ITER_* flags
4245 * @it: the task iterator to use
4247 * Initiate iteration through the tasks of @css. The caller can call
4248 * css_task_iter_next() to walk through the tasks until the function
4249 * returns NULL. On completion of iteration, css_task_iter_end() must be
4252 void css_task_iter_start(struct cgroup_subsys_state
*css
, unsigned int flags
,
4253 struct css_task_iter
*it
)
4255 /* no one should try to iterate before mounting cgroups */
4256 WARN_ON_ONCE(!use_task_css_set_links
);
4258 memset(it
, 0, sizeof(*it
));
4260 spin_lock_irq(&css_set_lock
);
4266 it
->cset_pos
= &css
->cgroup
->e_csets
[css
->ss
->id
];
4268 it
->cset_pos
= &css
->cgroup
->cset_links
;
4270 it
->cset_head
= it
->cset_pos
;
4272 css_task_iter_advance_css_set(it
);
4274 spin_unlock_irq(&css_set_lock
);
4278 * css_task_iter_next - return the next task for the iterator
4279 * @it: the task iterator being iterated
4281 * The "next" function for task iteration. @it should have been
4282 * initialized via css_task_iter_start(). Returns NULL when the iteration
4285 struct task_struct
*css_task_iter_next(struct css_task_iter
*it
)
4288 put_task_struct(it
->cur_task
);
4289 it
->cur_task
= NULL
;
4292 spin_lock_irq(&css_set_lock
);
4295 it
->cur_task
= list_entry(it
->task_pos
, struct task_struct
,
4297 get_task_struct(it
->cur_task
);
4298 css_task_iter_advance(it
);
4301 spin_unlock_irq(&css_set_lock
);
4303 return it
->cur_task
;
4307 * css_task_iter_end - finish task iteration
4308 * @it: the task iterator to finish
4310 * Finish task iteration started by css_task_iter_start().
4312 void css_task_iter_end(struct css_task_iter
*it
)
4315 spin_lock_irq(&css_set_lock
);
4316 list_del(&it
->iters_node
);
4317 put_css_set_locked(it
->cur_cset
);
4318 spin_unlock_irq(&css_set_lock
);
4322 put_css_set(it
->cur_dcset
);
4325 put_task_struct(it
->cur_task
);
4328 static void cgroup_procs_release(struct kernfs_open_file
*of
)
4331 css_task_iter_end(of
->priv
);
4336 static void *cgroup_procs_next(struct seq_file
*s
, void *v
, loff_t
*pos
)
4338 struct kernfs_open_file
*of
= s
->private;
4339 struct css_task_iter
*it
= of
->priv
;
4341 return css_task_iter_next(it
);
4344 static void *__cgroup_procs_start(struct seq_file
*s
, loff_t
*pos
,
4345 unsigned int iter_flags
)
4347 struct kernfs_open_file
*of
= s
->private;
4348 struct cgroup
*cgrp
= seq_css(s
)->cgroup
;
4349 struct css_task_iter
*it
= of
->priv
;
4352 * When a seq_file is seeked, it's always traversed sequentially
4353 * from position 0, so we can simply keep iterating on !0 *pos.
4356 if (WARN_ON_ONCE((*pos
)++))
4357 return ERR_PTR(-EINVAL
);
4359 it
= kzalloc(sizeof(*it
), GFP_KERNEL
);
4361 return ERR_PTR(-ENOMEM
);
4363 css_task_iter_start(&cgrp
->self
, iter_flags
, it
);
4364 } else if (!(*pos
)++) {
4365 css_task_iter_end(it
);
4366 css_task_iter_start(&cgrp
->self
, iter_flags
, it
);
4369 return cgroup_procs_next(s
, NULL
, NULL
);
4372 static void *cgroup_procs_start(struct seq_file
*s
, loff_t
*pos
)
4374 struct cgroup
*cgrp
= seq_css(s
)->cgroup
;
4377 * All processes of a threaded subtree belong to the domain cgroup
4378 * of the subtree. Only threads can be distributed across the
4379 * subtree. Reject reads on cgroup.procs in the subtree proper.
4380 * They're always empty anyway.
4382 if (cgroup_is_threaded(cgrp
))
4383 return ERR_PTR(-EOPNOTSUPP
);
4385 return __cgroup_procs_start(s
, pos
, CSS_TASK_ITER_PROCS
|
4386 CSS_TASK_ITER_THREADED
);
4389 static int cgroup_procs_show(struct seq_file
*s
, void *v
)
4391 seq_printf(s
, "%d\n", task_pid_vnr(v
));
4395 static int cgroup_procs_write_permission(struct cgroup
*src_cgrp
,
4396 struct cgroup
*dst_cgrp
,
4397 struct super_block
*sb
)
4399 struct cgroup_namespace
*ns
= current
->nsproxy
->cgroup_ns
;
4400 struct cgroup
*com_cgrp
= src_cgrp
;
4401 struct inode
*inode
;
4404 lockdep_assert_held(&cgroup_mutex
);
4406 /* find the common ancestor */
4407 while (!cgroup_is_descendant(dst_cgrp
, com_cgrp
))
4408 com_cgrp
= cgroup_parent(com_cgrp
);
4410 /* %current should be authorized to migrate to the common ancestor */
4411 inode
= kernfs_get_inode(sb
, com_cgrp
->procs_file
.kn
);
4415 ret
= inode_permission(inode
, MAY_WRITE
);
4421 * If namespaces are delegation boundaries, %current must be able
4422 * to see both source and destination cgroups from its namespace.
4424 if ((cgrp_dfl_root
.flags
& CGRP_ROOT_NS_DELEGATE
) &&
4425 (!cgroup_is_descendant(src_cgrp
, ns
->root_cset
->dfl_cgrp
) ||
4426 !cgroup_is_descendant(dst_cgrp
, ns
->root_cset
->dfl_cgrp
)))
4432 static ssize_t
cgroup_procs_write(struct kernfs_open_file
*of
,
4433 char *buf
, size_t nbytes
, loff_t off
)
4435 struct cgroup
*src_cgrp
, *dst_cgrp
;
4436 struct task_struct
*task
;
4439 dst_cgrp
= cgroup_kn_lock_live(of
->kn
, false);
4443 task
= cgroup_procs_write_start(buf
, true);
4444 ret
= PTR_ERR_OR_ZERO(task
);
4448 /* find the source cgroup */
4449 spin_lock_irq(&css_set_lock
);
4450 src_cgrp
= task_cgroup_from_root(task
, &cgrp_dfl_root
);
4451 spin_unlock_irq(&css_set_lock
);
4453 ret
= cgroup_procs_write_permission(src_cgrp
, dst_cgrp
,
4454 of
->file
->f_path
.dentry
->d_sb
);
4458 ret
= cgroup_attach_task(dst_cgrp
, task
, true);
4461 cgroup_procs_write_finish(task
);
4463 cgroup_kn_unlock(of
->kn
);
4465 return ret
?: nbytes
;
4468 static void *cgroup_threads_start(struct seq_file
*s
, loff_t
*pos
)
4470 return __cgroup_procs_start(s
, pos
, 0);
4473 static ssize_t
cgroup_threads_write(struct kernfs_open_file
*of
,
4474 char *buf
, size_t nbytes
, loff_t off
)
4476 struct cgroup
*src_cgrp
, *dst_cgrp
;
4477 struct task_struct
*task
;
4480 buf
= strstrip(buf
);
4482 dst_cgrp
= cgroup_kn_lock_live(of
->kn
, false);
4486 task
= cgroup_procs_write_start(buf
, false);
4487 ret
= PTR_ERR_OR_ZERO(task
);
4491 /* find the source cgroup */
4492 spin_lock_irq(&css_set_lock
);
4493 src_cgrp
= task_cgroup_from_root(task
, &cgrp_dfl_root
);
4494 spin_unlock_irq(&css_set_lock
);
4496 /* thread migrations follow the cgroup.procs delegation rule */
4497 ret
= cgroup_procs_write_permission(src_cgrp
, dst_cgrp
,
4498 of
->file
->f_path
.dentry
->d_sb
);
4502 /* and must be contained in the same domain */
4504 if (src_cgrp
->dom_cgrp
!= dst_cgrp
->dom_cgrp
)
4507 ret
= cgroup_attach_task(dst_cgrp
, task
, false);
4510 cgroup_procs_write_finish(task
);
4512 cgroup_kn_unlock(of
->kn
);
4514 return ret
?: nbytes
;
4517 /* cgroup core interface files for the default hierarchy */
4518 static struct cftype cgroup_base_files
[] = {
4520 .name
= "cgroup.type",
4521 .flags
= CFTYPE_NOT_ON_ROOT
,
4522 .seq_show
= cgroup_type_show
,
4523 .write
= cgroup_type_write
,
4526 .name
= "cgroup.procs",
4527 .flags
= CFTYPE_NS_DELEGATABLE
,
4528 .file_offset
= offsetof(struct cgroup
, procs_file
),
4529 .release
= cgroup_procs_release
,
4530 .seq_start
= cgroup_procs_start
,
4531 .seq_next
= cgroup_procs_next
,
4532 .seq_show
= cgroup_procs_show
,
4533 .write
= cgroup_procs_write
,
4536 .name
= "cgroup.threads",
4537 .flags
= CFTYPE_NS_DELEGATABLE
,
4538 .release
= cgroup_procs_release
,
4539 .seq_start
= cgroup_threads_start
,
4540 .seq_next
= cgroup_procs_next
,
4541 .seq_show
= cgroup_procs_show
,
4542 .write
= cgroup_threads_write
,
4545 .name
= "cgroup.controllers",
4546 .seq_show
= cgroup_controllers_show
,
4549 .name
= "cgroup.subtree_control",
4550 .flags
= CFTYPE_NS_DELEGATABLE
,
4551 .seq_show
= cgroup_subtree_control_show
,
4552 .write
= cgroup_subtree_control_write
,
4555 .name
= "cgroup.events",
4556 .flags
= CFTYPE_NOT_ON_ROOT
,
4557 .file_offset
= offsetof(struct cgroup
, events_file
),
4558 .seq_show
= cgroup_events_show
,
4561 .name
= "cgroup.max.descendants",
4562 .seq_show
= cgroup_max_descendants_show
,
4563 .write
= cgroup_max_descendants_write
,
4566 .name
= "cgroup.max.depth",
4567 .seq_show
= cgroup_max_depth_show
,
4568 .write
= cgroup_max_depth_write
,
4571 .name
= "cgroup.stat",
4572 .seq_show
= cgroup_stat_show
,
4576 .flags
= CFTYPE_NOT_ON_ROOT
,
4577 .seq_show
= cpu_stat_show
,
4583 * css destruction is four-stage process.
4585 * 1. Destruction starts. Killing of the percpu_ref is initiated.
4586 * Implemented in kill_css().
4588 * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
4589 * and thus css_tryget_online() is guaranteed to fail, the css can be
4590 * offlined by invoking offline_css(). After offlining, the base ref is
4591 * put. Implemented in css_killed_work_fn().
4593 * 3. When the percpu_ref reaches zero, the only possible remaining
4594 * accessors are inside RCU read sections. css_release() schedules the
4597 * 4. After the grace period, the css can be freed. Implemented in
4598 * css_free_work_fn().
4600 * It is actually hairier because both step 2 and 4 require process context
4601 * and thus involve punting to css->destroy_work adding two additional
4602 * steps to the already complex sequence.
4604 static void css_free_rwork_fn(struct work_struct
*work
)
4606 struct cgroup_subsys_state
*css
= container_of(to_rcu_work(work
),
4607 struct cgroup_subsys_state
, destroy_rwork
);
4608 struct cgroup_subsys
*ss
= css
->ss
;
4609 struct cgroup
*cgrp
= css
->cgroup
;
4611 percpu_ref_exit(&css
->refcnt
);
4615 struct cgroup_subsys_state
*parent
= css
->parent
;
4619 cgroup_idr_remove(&ss
->css_idr
, id
);
4625 /* cgroup free path */
4626 atomic_dec(&cgrp
->root
->nr_cgrps
);
4627 cgroup1_pidlist_destroy_all(cgrp
);
4628 cancel_work_sync(&cgrp
->release_agent_work
);
4630 if (cgroup_parent(cgrp
)) {
4632 * We get a ref to the parent, and put the ref when
4633 * this cgroup is being freed, so it's guaranteed
4634 * that the parent won't be destroyed before its
4637 cgroup_put(cgroup_parent(cgrp
));
4638 kernfs_put(cgrp
->kn
);
4639 if (cgroup_on_dfl(cgrp
))
4640 cgroup_rstat_exit(cgrp
);
4644 * This is root cgroup's refcnt reaching zero,
4645 * which indicates that the root should be
4648 cgroup_destroy_root(cgrp
->root
);
4653 static void css_release_work_fn(struct work_struct
*work
)
4655 struct cgroup_subsys_state
*css
=
4656 container_of(work
, struct cgroup_subsys_state
, destroy_work
);
4657 struct cgroup_subsys
*ss
= css
->ss
;
4658 struct cgroup
*cgrp
= css
->cgroup
;
4660 mutex_lock(&cgroup_mutex
);
4662 css
->flags
|= CSS_RELEASED
;
4663 list_del_rcu(&css
->sibling
);
4666 /* css release path */
4667 if (!list_empty(&css
->rstat_css_node
)) {
4668 cgroup_rstat_flush(cgrp
);
4669 list_del_rcu(&css
->rstat_css_node
);
4672 cgroup_idr_replace(&ss
->css_idr
, NULL
, css
->id
);
4673 if (ss
->css_released
)
4674 ss
->css_released(css
);
4676 struct cgroup
*tcgrp
;
4678 /* cgroup release path */
4679 TRACE_CGROUP_PATH(release
, cgrp
);
4681 if (cgroup_on_dfl(cgrp
))
4682 cgroup_rstat_flush(cgrp
);
4684 for (tcgrp
= cgroup_parent(cgrp
); tcgrp
;
4685 tcgrp
= cgroup_parent(tcgrp
))
4686 tcgrp
->nr_dying_descendants
--;
4688 cgroup_idr_remove(&cgrp
->root
->cgroup_idr
, cgrp
->id
);
4692 * There are two control paths which try to determine
4693 * cgroup from dentry without going through kernfs -
4694 * cgroupstats_build() and css_tryget_online_from_dir().
4695 * Those are supported by RCU protecting clearing of
4696 * cgrp->kn->priv backpointer.
4699 RCU_INIT_POINTER(*(void __rcu __force
**)&cgrp
->kn
->priv
,
4702 cgroup_bpf_put(cgrp
);
4705 mutex_unlock(&cgroup_mutex
);
4707 INIT_RCU_WORK(&css
->destroy_rwork
, css_free_rwork_fn
);
4708 queue_rcu_work(cgroup_destroy_wq
, &css
->destroy_rwork
);
4711 static void css_release(struct percpu_ref
*ref
)
4713 struct cgroup_subsys_state
*css
=
4714 container_of(ref
, struct cgroup_subsys_state
, refcnt
);
4716 INIT_WORK(&css
->destroy_work
, css_release_work_fn
);
4717 queue_work(cgroup_destroy_wq
, &css
->destroy_work
);
4720 static void init_and_link_css(struct cgroup_subsys_state
*css
,
4721 struct cgroup_subsys
*ss
, struct cgroup
*cgrp
)
4723 lockdep_assert_held(&cgroup_mutex
);
4725 cgroup_get_live(cgrp
);
4727 memset(css
, 0, sizeof(*css
));
4731 INIT_LIST_HEAD(&css
->sibling
);
4732 INIT_LIST_HEAD(&css
->children
);
4733 INIT_LIST_HEAD(&css
->rstat_css_node
);
4734 css
->serial_nr
= css_serial_nr_next
++;
4735 atomic_set(&css
->online_cnt
, 0);
4737 if (cgroup_parent(cgrp
)) {
4738 css
->parent
= cgroup_css(cgroup_parent(cgrp
), ss
);
4739 css_get(css
->parent
);
4742 if (cgroup_on_dfl(cgrp
) && ss
->css_rstat_flush
)
4743 list_add_rcu(&css
->rstat_css_node
, &cgrp
->rstat_css_list
);
4745 BUG_ON(cgroup_css(cgrp
, ss
));
4748 /* invoke ->css_online() on a new CSS and mark it online if successful */
4749 static int online_css(struct cgroup_subsys_state
*css
)
4751 struct cgroup_subsys
*ss
= css
->ss
;
4754 lockdep_assert_held(&cgroup_mutex
);
4757 ret
= ss
->css_online(css
);
4759 css
->flags
|= CSS_ONLINE
;
4760 rcu_assign_pointer(css
->cgroup
->subsys
[ss
->id
], css
);
4762 atomic_inc(&css
->online_cnt
);
4764 atomic_inc(&css
->parent
->online_cnt
);
4769 /* if the CSS is online, invoke ->css_offline() on it and mark it offline */
4770 static void offline_css(struct cgroup_subsys_state
*css
)
4772 struct cgroup_subsys
*ss
= css
->ss
;
4774 lockdep_assert_held(&cgroup_mutex
);
4776 if (!(css
->flags
& CSS_ONLINE
))
4779 if (ss
->css_offline
)
4780 ss
->css_offline(css
);
4782 css
->flags
&= ~CSS_ONLINE
;
4783 RCU_INIT_POINTER(css
->cgroup
->subsys
[ss
->id
], NULL
);
4785 wake_up_all(&css
->cgroup
->offline_waitq
);
4789 * css_create - create a cgroup_subsys_state
4790 * @cgrp: the cgroup new css will be associated with
4791 * @ss: the subsys of new css
4793 * Create a new css associated with @cgrp - @ss pair. On success, the new
4794 * css is online and installed in @cgrp. This function doesn't create the
4795 * interface files. Returns 0 on success, -errno on failure.
4797 static struct cgroup_subsys_state
*css_create(struct cgroup
*cgrp
,
4798 struct cgroup_subsys
*ss
)
4800 struct cgroup
*parent
= cgroup_parent(cgrp
);
4801 struct cgroup_subsys_state
*parent_css
= cgroup_css(parent
, ss
);
4802 struct cgroup_subsys_state
*css
;
4805 lockdep_assert_held(&cgroup_mutex
);
4807 css
= ss
->css_alloc(parent_css
);
4809 css
= ERR_PTR(-ENOMEM
);
4813 init_and_link_css(css
, ss
, cgrp
);
4815 err
= percpu_ref_init(&css
->refcnt
, css_release
, 0, GFP_KERNEL
);
4819 err
= cgroup_idr_alloc(&ss
->css_idr
, NULL
, 2, 0, GFP_KERNEL
);
4824 /* @css is ready to be brought online now, make it visible */
4825 list_add_tail_rcu(&css
->sibling
, &parent_css
->children
);
4826 cgroup_idr_replace(&ss
->css_idr
, css
, css
->id
);
4828 err
= online_css(css
);
4832 if (ss
->broken_hierarchy
&& !ss
->warned_broken_hierarchy
&&
4833 cgroup_parent(parent
)) {
4834 pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
4835 current
->comm
, current
->pid
, ss
->name
);
4836 if (!strcmp(ss
->name
, "memory"))
4837 pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n");
4838 ss
->warned_broken_hierarchy
= true;
4844 list_del_rcu(&css
->sibling
);
4846 list_del_rcu(&css
->rstat_css_node
);
4847 INIT_RCU_WORK(&css
->destroy_rwork
, css_free_rwork_fn
);
4848 queue_rcu_work(cgroup_destroy_wq
, &css
->destroy_rwork
);
4849 return ERR_PTR(err
);
4853 * The returned cgroup is fully initialized including its control mask, but
4854 * it isn't associated with its kernfs_node and doesn't have the control
4857 static struct cgroup
*cgroup_create(struct cgroup
*parent
)
4859 struct cgroup_root
*root
= parent
->root
;
4860 struct cgroup
*cgrp
, *tcgrp
;
4861 int level
= parent
->level
+ 1;
4864 /* allocate the cgroup and its ID, 0 is reserved for the root */
4865 cgrp
= kzalloc(struct_size(cgrp
, ancestor_ids
, (level
+ 1)),
4868 return ERR_PTR(-ENOMEM
);
4870 ret
= percpu_ref_init(&cgrp
->self
.refcnt
, css_release
, 0, GFP_KERNEL
);
4874 if (cgroup_on_dfl(parent
)) {
4875 ret
= cgroup_rstat_init(cgrp
);
4877 goto out_cancel_ref
;
4881 * Temporarily set the pointer to NULL, so idr_find() won't return
4882 * a half-baked cgroup.
4884 cgrp
->id
= cgroup_idr_alloc(&root
->cgroup_idr
, NULL
, 2, 0, GFP_KERNEL
);
4890 init_cgroup_housekeeping(cgrp
);
4892 cgrp
->self
.parent
= &parent
->self
;
4894 cgrp
->level
= level
;
4895 ret
= cgroup_bpf_inherit(cgrp
);
4899 for (tcgrp
= cgrp
; tcgrp
; tcgrp
= cgroup_parent(tcgrp
)) {
4900 cgrp
->ancestor_ids
[tcgrp
->level
] = tcgrp
->id
;
4903 tcgrp
->nr_descendants
++;
4906 if (notify_on_release(parent
))
4907 set_bit(CGRP_NOTIFY_ON_RELEASE
, &cgrp
->flags
);
4909 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN
, &parent
->flags
))
4910 set_bit(CGRP_CPUSET_CLONE_CHILDREN
, &cgrp
->flags
);
4912 cgrp
->self
.serial_nr
= css_serial_nr_next
++;
4914 /* allocation complete, commit to creation */
4915 list_add_tail_rcu(&cgrp
->self
.sibling
, &cgroup_parent(cgrp
)->self
.children
);
4916 atomic_inc(&root
->nr_cgrps
);
4917 cgroup_get_live(parent
);
4920 * @cgrp is now fully operational. If something fails after this
4921 * point, it'll be released via the normal destruction path.
4923 cgroup_idr_replace(&root
->cgroup_idr
, cgrp
, cgrp
->id
);
4926 * On the default hierarchy, a child doesn't automatically inherit
4927 * subtree_control from the parent. Each is configured manually.
4929 if (!cgroup_on_dfl(cgrp
))
4930 cgrp
->subtree_control
= cgroup_control(cgrp
);
4932 cgroup_propagate_control(cgrp
);
4937 cgroup_idr_remove(&root
->cgroup_idr
, cgrp
->id
);
4939 if (cgroup_on_dfl(parent
))
4940 cgroup_rstat_exit(cgrp
);
4942 percpu_ref_exit(&cgrp
->self
.refcnt
);
4945 return ERR_PTR(ret
);
4948 static bool cgroup_check_hierarchy_limits(struct cgroup
*parent
)
4950 struct cgroup
*cgroup
;
4954 lockdep_assert_held(&cgroup_mutex
);
4956 for (cgroup
= parent
; cgroup
; cgroup
= cgroup_parent(cgroup
)) {
4957 if (cgroup
->nr_descendants
>= cgroup
->max_descendants
)
4960 if (level
> cgroup
->max_depth
)
4971 int cgroup_mkdir(struct kernfs_node
*parent_kn
, const char *name
, umode_t mode
)
4973 struct cgroup
*parent
, *cgrp
;
4974 struct kernfs_node
*kn
;
4977 /* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */
4978 if (strchr(name
, '\n'))
4981 parent
= cgroup_kn_lock_live(parent_kn
, false);
4985 if (!cgroup_check_hierarchy_limits(parent
)) {
4990 cgrp
= cgroup_create(parent
);
4992 ret
= PTR_ERR(cgrp
);
4996 /* create the directory */
4997 kn
= kernfs_create_dir(parent
->kn
, name
, mode
, cgrp
);
5005 * This extra ref will be put in cgroup_free_fn() and guarantees
5006 * that @cgrp->kn is always accessible.
5010 ret
= cgroup_kn_set_ugid(kn
);
5014 ret
= css_populate_dir(&cgrp
->self
);
5018 ret
= cgroup_apply_control_enable(cgrp
);
5022 TRACE_CGROUP_PATH(mkdir
, cgrp
);
5024 /* let's create and online css's */
5025 kernfs_activate(kn
);
5031 cgroup_destroy_locked(cgrp
);
5033 cgroup_kn_unlock(parent_kn
);
5038 * This is called when the refcnt of a css is confirmed to be killed.
5039 * css_tryget_online() is now guaranteed to fail. Tell the subsystem to
5040 * initate destruction and put the css ref from kill_css().
5042 static void css_killed_work_fn(struct work_struct
*work
)
5044 struct cgroup_subsys_state
*css
=
5045 container_of(work
, struct cgroup_subsys_state
, destroy_work
);
5047 mutex_lock(&cgroup_mutex
);
5052 /* @css can't go away while we're holding cgroup_mutex */
5054 } while (css
&& atomic_dec_and_test(&css
->online_cnt
));
5056 mutex_unlock(&cgroup_mutex
);
5059 /* css kill confirmation processing requires process context, bounce */
5060 static void css_killed_ref_fn(struct percpu_ref
*ref
)
5062 struct cgroup_subsys_state
*css
=
5063 container_of(ref
, struct cgroup_subsys_state
, refcnt
);
5065 if (atomic_dec_and_test(&css
->online_cnt
)) {
5066 INIT_WORK(&css
->destroy_work
, css_killed_work_fn
);
5067 queue_work(cgroup_destroy_wq
, &css
->destroy_work
);
5072 * kill_css - destroy a css
5073 * @css: css to destroy
5075 * This function initiates destruction of @css by removing cgroup interface
5076 * files and putting its base reference. ->css_offline() will be invoked
5077 * asynchronously once css_tryget_online() is guaranteed to fail and when
5078 * the reference count reaches zero, @css will be released.
5080 static void kill_css(struct cgroup_subsys_state
*css
)
5082 lockdep_assert_held(&cgroup_mutex
);
5084 if (css
->flags
& CSS_DYING
)
5087 css
->flags
|= CSS_DYING
;
5090 * This must happen before css is disassociated with its cgroup.
5091 * See seq_css() for details.
5096 * Killing would put the base ref, but we need to keep it alive
5097 * until after ->css_offline().
5102 * cgroup core guarantees that, by the time ->css_offline() is
5103 * invoked, no new css reference will be given out via
5104 * css_tryget_online(). We can't simply call percpu_ref_kill() and
5105 * proceed to offlining css's because percpu_ref_kill() doesn't
5106 * guarantee that the ref is seen as killed on all CPUs on return.
5108 * Use percpu_ref_kill_and_confirm() to get notifications as each
5109 * css is confirmed to be seen as killed on all CPUs.
5111 percpu_ref_kill_and_confirm(&css
->refcnt
, css_killed_ref_fn
);
5115 * cgroup_destroy_locked - the first stage of cgroup destruction
5116 * @cgrp: cgroup to be destroyed
5118 * css's make use of percpu refcnts whose killing latency shouldn't be
5119 * exposed to userland and are RCU protected. Also, cgroup core needs to
5120 * guarantee that css_tryget_online() won't succeed by the time
5121 * ->css_offline() is invoked. To satisfy all the requirements,
5122 * destruction is implemented in the following two steps.
5124 * s1. Verify @cgrp can be destroyed and mark it dying. Remove all
5125 * userland visible parts and start killing the percpu refcnts of
5126 * css's. Set up so that the next stage will be kicked off once all
5127 * the percpu refcnts are confirmed to be killed.
5129 * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
5130 * rest of destruction. Once all cgroup references are gone, the
5131 * cgroup is RCU-freed.
5133 * This function implements s1. After this step, @cgrp is gone as far as
5134 * the userland is concerned and a new cgroup with the same name may be
5135 * created. As cgroup doesn't care about the names internally, this
5136 * doesn't cause any problem.
5138 static int cgroup_destroy_locked(struct cgroup
*cgrp
)
5139 __releases(&cgroup_mutex
) __acquires(&cgroup_mutex
)
5141 struct cgroup
*tcgrp
, *parent
= cgroup_parent(cgrp
);
5142 struct cgroup_subsys_state
*css
;
5143 struct cgrp_cset_link
*link
;
5146 lockdep_assert_held(&cgroup_mutex
);
5149 * Only migration can raise populated from zero and we're already
5150 * holding cgroup_mutex.
5152 if (cgroup_is_populated(cgrp
))
5156 * Make sure there's no live children. We can't test emptiness of
5157 * ->self.children as dead children linger on it while being
5158 * drained; otherwise, "rmdir parent/child parent" may fail.
5160 if (css_has_online_children(&cgrp
->self
))
5164 * Mark @cgrp and the associated csets dead. The former prevents
5165 * further task migration and child creation by disabling
5166 * cgroup_lock_live_group(). The latter makes the csets ignored by
5167 * the migration path.
5169 cgrp
->self
.flags
&= ~CSS_ONLINE
;
5171 spin_lock_irq(&css_set_lock
);
5172 list_for_each_entry(link
, &cgrp
->cset_links
, cset_link
)
5173 link
->cset
->dead
= true;
5174 spin_unlock_irq(&css_set_lock
);
5176 /* initiate massacre of all css's */
5177 for_each_css(css
, ssid
, cgrp
)
5180 /* clear and remove @cgrp dir, @cgrp has an extra ref on its kn */
5181 css_clear_dir(&cgrp
->self
);
5182 kernfs_remove(cgrp
->kn
);
5184 if (parent
&& cgroup_is_threaded(cgrp
))
5185 parent
->nr_threaded_children
--;
5187 for (tcgrp
= cgroup_parent(cgrp
); tcgrp
; tcgrp
= cgroup_parent(tcgrp
)) {
5188 tcgrp
->nr_descendants
--;
5189 tcgrp
->nr_dying_descendants
++;
5192 cgroup1_check_for_release(parent
);
5194 /* put the base reference */
5195 percpu_ref_kill(&cgrp
->self
.refcnt
);
5200 int cgroup_rmdir(struct kernfs_node
*kn
)
5202 struct cgroup
*cgrp
;
5205 cgrp
= cgroup_kn_lock_live(kn
, false);
5209 ret
= cgroup_destroy_locked(cgrp
);
5211 TRACE_CGROUP_PATH(rmdir
, cgrp
);
5213 cgroup_kn_unlock(kn
);
5217 static struct kernfs_syscall_ops cgroup_kf_syscall_ops
= {
5218 .show_options
= cgroup_show_options
,
5219 .remount_fs
= cgroup_remount
,
5220 .mkdir
= cgroup_mkdir
,
5221 .rmdir
= cgroup_rmdir
,
5222 .show_path
= cgroup_show_path
,
5225 static void __init
cgroup_init_subsys(struct cgroup_subsys
*ss
, bool early
)
5227 struct cgroup_subsys_state
*css
;
5229 pr_debug("Initializing cgroup subsys %s\n", ss
->name
);
5231 mutex_lock(&cgroup_mutex
);
5233 idr_init(&ss
->css_idr
);
5234 INIT_LIST_HEAD(&ss
->cfts
);
5236 /* Create the root cgroup state for this subsystem */
5237 ss
->root
= &cgrp_dfl_root
;
5238 css
= ss
->css_alloc(cgroup_css(&cgrp_dfl_root
.cgrp
, ss
));
5239 /* We don't handle early failures gracefully */
5240 BUG_ON(IS_ERR(css
));
5241 init_and_link_css(css
, ss
, &cgrp_dfl_root
.cgrp
);
5244 * Root csses are never destroyed and we can't initialize
5245 * percpu_ref during early init. Disable refcnting.
5247 css
->flags
|= CSS_NO_REF
;
5250 /* allocation can't be done safely during early init */
5253 css
->id
= cgroup_idr_alloc(&ss
->css_idr
, css
, 1, 2, GFP_KERNEL
);
5254 BUG_ON(css
->id
< 0);
5257 /* Update the init_css_set to contain a subsys
5258 * pointer to this state - since the subsystem is
5259 * newly registered, all tasks and hence the
5260 * init_css_set is in the subsystem's root cgroup. */
5261 init_css_set
.subsys
[ss
->id
] = css
;
5263 have_fork_callback
|= (bool)ss
->fork
<< ss
->id
;
5264 have_exit_callback
|= (bool)ss
->exit
<< ss
->id
;
5265 have_free_callback
|= (bool)ss
->free
<< ss
->id
;
5266 have_canfork_callback
|= (bool)ss
->can_fork
<< ss
->id
;
5268 /* At system boot, before all subsystems have been
5269 * registered, no tasks have been forked, so we don't
5270 * need to invoke fork callbacks here. */
5271 BUG_ON(!list_empty(&init_task
.tasks
));
5273 BUG_ON(online_css(css
));
5275 mutex_unlock(&cgroup_mutex
);
5279 * cgroup_init_early - cgroup initialization at system boot
5281 * Initialize cgroups at system boot, and initialize any
5282 * subsystems that request early init.
5284 int __init
cgroup_init_early(void)
5286 static struct cgroup_sb_opts __initdata opts
;
5287 struct cgroup_subsys
*ss
;
5290 init_cgroup_root(&cgrp_dfl_root
, &opts
);
5291 cgrp_dfl_root
.cgrp
.self
.flags
|= CSS_NO_REF
;
5293 RCU_INIT_POINTER(init_task
.cgroups
, &init_css_set
);
5295 for_each_subsys(ss
, i
) {
5296 WARN(!ss
->css_alloc
|| !ss
->css_free
|| ss
->name
|| ss
->id
,
5297 "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p id:name=%d:%s\n",
5298 i
, cgroup_subsys_name
[i
], ss
->css_alloc
, ss
->css_free
,
5300 WARN(strlen(cgroup_subsys_name
[i
]) > MAX_CGROUP_TYPE_NAMELEN
,
5301 "cgroup_subsys_name %s too long\n", cgroup_subsys_name
[i
]);
5304 ss
->name
= cgroup_subsys_name
[i
];
5305 if (!ss
->legacy_name
)
5306 ss
->legacy_name
= cgroup_subsys_name
[i
];
5309 cgroup_init_subsys(ss
, true);
5314 static u16 cgroup_disable_mask __initdata
;
5317 * cgroup_init - cgroup initialization
5319 * Register cgroup filesystem and /proc file, and initialize
5320 * any subsystems that didn't request early init.
5322 int __init
cgroup_init(void)
5324 struct cgroup_subsys
*ss
;
5327 BUILD_BUG_ON(CGROUP_SUBSYS_COUNT
> 16);
5328 BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem
));
5329 BUG_ON(cgroup_init_cftypes(NULL
, cgroup_base_files
));
5330 BUG_ON(cgroup_init_cftypes(NULL
, cgroup1_base_files
));
5332 cgroup_rstat_boot();
5335 * The latency of the synchronize_sched() is too high for cgroups,
5336 * avoid it at the cost of forcing all readers into the slow path.
5338 rcu_sync_enter_start(&cgroup_threadgroup_rwsem
.rss
);
5340 get_user_ns(init_cgroup_ns
.user_ns
);
5342 mutex_lock(&cgroup_mutex
);
5345 * Add init_css_set to the hash table so that dfl_root can link to
5348 hash_add(css_set_table
, &init_css_set
.hlist
,
5349 css_set_hash(init_css_set
.subsys
));
5351 BUG_ON(cgroup_setup_root(&cgrp_dfl_root
, 0, 0));
5353 mutex_unlock(&cgroup_mutex
);
5355 for_each_subsys(ss
, ssid
) {
5356 if (ss
->early_init
) {
5357 struct cgroup_subsys_state
*css
=
5358 init_css_set
.subsys
[ss
->id
];
5360 css
->id
= cgroup_idr_alloc(&ss
->css_idr
, css
, 1, 2,
5362 BUG_ON(css
->id
< 0);
5364 cgroup_init_subsys(ss
, false);
5367 list_add_tail(&init_css_set
.e_cset_node
[ssid
],
5368 &cgrp_dfl_root
.cgrp
.e_csets
[ssid
]);
5371 * Setting dfl_root subsys_mask needs to consider the
5372 * disabled flag and cftype registration needs kmalloc,
5373 * both of which aren't available during early_init.
5375 if (cgroup_disable_mask
& (1 << ssid
)) {
5376 static_branch_disable(cgroup_subsys_enabled_key
[ssid
]);
5377 printk(KERN_INFO
"Disabling %s control group subsystem\n",
5382 if (cgroup1_ssid_disabled(ssid
))
5383 printk(KERN_INFO
"Disabling %s control group subsystem in v1 mounts\n",
5386 cgrp_dfl_root
.subsys_mask
|= 1 << ss
->id
;
5388 /* implicit controllers must be threaded too */
5389 WARN_ON(ss
->implicit_on_dfl
&& !ss
->threaded
);
5391 if (ss
->implicit_on_dfl
)
5392 cgrp_dfl_implicit_ss_mask
|= 1 << ss
->id
;
5393 else if (!ss
->dfl_cftypes
)
5394 cgrp_dfl_inhibit_ss_mask
|= 1 << ss
->id
;
5397 cgrp_dfl_threaded_ss_mask
|= 1 << ss
->id
;
5399 if (ss
->dfl_cftypes
== ss
->legacy_cftypes
) {
5400 WARN_ON(cgroup_add_cftypes(ss
, ss
->dfl_cftypes
));
5402 WARN_ON(cgroup_add_dfl_cftypes(ss
, ss
->dfl_cftypes
));
5403 WARN_ON(cgroup_add_legacy_cftypes(ss
, ss
->legacy_cftypes
));
5407 ss
->bind(init_css_set
.subsys
[ssid
]);
5409 mutex_lock(&cgroup_mutex
);
5410 css_populate_dir(init_css_set
.subsys
[ssid
]);
5411 mutex_unlock(&cgroup_mutex
);
5414 /* init_css_set.subsys[] has been updated, re-hash */
5415 hash_del(&init_css_set
.hlist
);
5416 hash_add(css_set_table
, &init_css_set
.hlist
,
5417 css_set_hash(init_css_set
.subsys
));
5419 WARN_ON(sysfs_create_mount_point(fs_kobj
, "cgroup"));
5420 WARN_ON(register_filesystem(&cgroup_fs_type
));
5421 WARN_ON(register_filesystem(&cgroup2_fs_type
));
5422 WARN_ON(!proc_create_single("cgroups", 0, NULL
, proc_cgroupstats_show
));
5427 static int __init
cgroup_wq_init(void)
5430 * There isn't much point in executing destruction path in
5431 * parallel. Good chunk is serialized with cgroup_mutex anyway.
5432 * Use 1 for @max_active.
5434 * We would prefer to do this in cgroup_init() above, but that
5435 * is called before init_workqueues(): so leave this until after.
5437 cgroup_destroy_wq
= alloc_workqueue("cgroup_destroy", 0, 1);
5438 BUG_ON(!cgroup_destroy_wq
);
5441 core_initcall(cgroup_wq_init
);
5443 void cgroup_path_from_kernfs_id(const union kernfs_node_id
*id
,
5444 char *buf
, size_t buflen
)
5446 struct kernfs_node
*kn
;
5448 kn
= kernfs_get_node_by_id(cgrp_dfl_root
.kf_root
, id
);
5451 kernfs_path(kn
, buf
, buflen
);
5456 * proc_cgroup_show()
5457 * - Print task's cgroup paths into seq_file, one line for each hierarchy
5458 * - Used for /proc/<pid>/cgroup.
5460 int proc_cgroup_show(struct seq_file
*m
, struct pid_namespace
*ns
,
5461 struct pid
*pid
, struct task_struct
*tsk
)
5465 struct cgroup_root
*root
;
5468 buf
= kmalloc(PATH_MAX
, GFP_KERNEL
);
5472 mutex_lock(&cgroup_mutex
);
5473 spin_lock_irq(&css_set_lock
);
5475 for_each_root(root
) {
5476 struct cgroup_subsys
*ss
;
5477 struct cgroup
*cgrp
;
5478 int ssid
, count
= 0;
5480 if (root
== &cgrp_dfl_root
&& !cgrp_dfl_visible
)
5483 seq_printf(m
, "%d:", root
->hierarchy_id
);
5484 if (root
!= &cgrp_dfl_root
)
5485 for_each_subsys(ss
, ssid
)
5486 if (root
->subsys_mask
& (1 << ssid
))
5487 seq_printf(m
, "%s%s", count
++ ? "," : "",
5489 if (strlen(root
->name
))
5490 seq_printf(m
, "%sname=%s", count
? "," : "",
5494 cgrp
= task_cgroup_from_root(tsk
, root
);
5497 * On traditional hierarchies, all zombie tasks show up as
5498 * belonging to the root cgroup. On the default hierarchy,
5499 * while a zombie doesn't show up in "cgroup.procs" and
5500 * thus can't be migrated, its /proc/PID/cgroup keeps
5501 * reporting the cgroup it belonged to before exiting. If
5502 * the cgroup is removed before the zombie is reaped,
5503 * " (deleted)" is appended to the cgroup path.
5505 if (cgroup_on_dfl(cgrp
) || !(tsk
->flags
& PF_EXITING
)) {
5506 retval
= cgroup_path_ns_locked(cgrp
, buf
, PATH_MAX
,
5507 current
->nsproxy
->cgroup_ns
);
5508 if (retval
>= PATH_MAX
)
5509 retval
= -ENAMETOOLONG
;
5518 if (cgroup_on_dfl(cgrp
) && cgroup_is_dead(cgrp
))
5519 seq_puts(m
, " (deleted)\n");
5526 spin_unlock_irq(&css_set_lock
);
5527 mutex_unlock(&cgroup_mutex
);
5534 * cgroup_fork - initialize cgroup related fields during copy_process()
5535 * @child: pointer to task_struct of forking parent process.
5537 * A task is associated with the init_css_set until cgroup_post_fork()
5538 * attaches it to the parent's css_set. Empty cg_list indicates that
5539 * @child isn't holding reference to its css_set.
5541 void cgroup_fork(struct task_struct
*child
)
5543 RCU_INIT_POINTER(child
->cgroups
, &init_css_set
);
5544 INIT_LIST_HEAD(&child
->cg_list
);
5548 * cgroup_can_fork - called on a new task before the process is exposed
5549 * @child: the task in question.
5551 * This calls the subsystem can_fork() callbacks. If the can_fork() callback
5552 * returns an error, the fork aborts with that error code. This allows for
5553 * a cgroup subsystem to conditionally allow or deny new forks.
5555 int cgroup_can_fork(struct task_struct
*child
)
5557 struct cgroup_subsys
*ss
;
5560 do_each_subsys_mask(ss
, i
, have_canfork_callback
) {
5561 ret
= ss
->can_fork(child
);
5564 } while_each_subsys_mask();
5569 for_each_subsys(ss
, j
) {
5572 if (ss
->cancel_fork
)
5573 ss
->cancel_fork(child
);
5580 * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork()
5581 * @child: the task in question
5583 * This calls the cancel_fork() callbacks if a fork failed *after*
5584 * cgroup_can_fork() succeded.
5586 void cgroup_cancel_fork(struct task_struct
*child
)
5588 struct cgroup_subsys
*ss
;
5591 for_each_subsys(ss
, i
)
5592 if (ss
->cancel_fork
)
5593 ss
->cancel_fork(child
);
5597 * cgroup_post_fork - called on a new task after adding it to the task list
5598 * @child: the task in question
5600 * Adds the task to the list running through its css_set if necessary and
5601 * call the subsystem fork() callbacks. Has to be after the task is
5602 * visible on the task list in case we race with the first call to
5603 * cgroup_task_iter_start() - to guarantee that the new task ends up on its
5606 void cgroup_post_fork(struct task_struct
*child
)
5608 struct cgroup_subsys
*ss
;
5612 * This may race against cgroup_enable_task_cg_lists(). As that
5613 * function sets use_task_css_set_links before grabbing
5614 * tasklist_lock and we just went through tasklist_lock to add
5615 * @child, it's guaranteed that either we see the set
5616 * use_task_css_set_links or cgroup_enable_task_cg_lists() sees
5617 * @child during its iteration.
5619 * If we won the race, @child is associated with %current's
5620 * css_set. Grabbing css_set_lock guarantees both that the
5621 * association is stable, and, on completion of the parent's
5622 * migration, @child is visible in the source of migration or
5623 * already in the destination cgroup. This guarantee is necessary
5624 * when implementing operations which need to migrate all tasks of
5625 * a cgroup to another.
5627 * Note that if we lose to cgroup_enable_task_cg_lists(), @child
5628 * will remain in init_css_set. This is safe because all tasks are
5629 * in the init_css_set before cg_links is enabled and there's no
5630 * operation which transfers all tasks out of init_css_set.
5632 if (use_task_css_set_links
) {
5633 struct css_set
*cset
;
5635 spin_lock_irq(&css_set_lock
);
5636 cset
= task_css_set(current
);
5637 if (list_empty(&child
->cg_list
)) {
5640 css_set_move_task(child
, NULL
, cset
, false);
5642 spin_unlock_irq(&css_set_lock
);
5646 * Call ss->fork(). This must happen after @child is linked on
5647 * css_set; otherwise, @child might change state between ->fork()
5648 * and addition to css_set.
5650 do_each_subsys_mask(ss
, i
, have_fork_callback
) {
5652 } while_each_subsys_mask();
5656 * cgroup_exit - detach cgroup from exiting task
5657 * @tsk: pointer to task_struct of exiting process
5659 * Description: Detach cgroup from @tsk and release it.
5661 * Note that cgroups marked notify_on_release force every task in
5662 * them to take the global cgroup_mutex mutex when exiting.
5663 * This could impact scaling on very large systems. Be reluctant to
5664 * use notify_on_release cgroups where very high task exit scaling
5665 * is required on large systems.
5667 * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We
5668 * call cgroup_exit() while the task is still competent to handle
5669 * notify_on_release(), then leave the task attached to the root cgroup in
5670 * each hierarchy for the remainder of its exit. No need to bother with
5671 * init_css_set refcnting. init_css_set never goes away and we can't race
5672 * with migration path - PF_EXITING is visible to migration path.
5674 void cgroup_exit(struct task_struct
*tsk
)
5676 struct cgroup_subsys
*ss
;
5677 struct css_set
*cset
;
5681 * Unlink from @tsk from its css_set. As migration path can't race
5682 * with us, we can check css_set and cg_list without synchronization.
5684 cset
= task_css_set(tsk
);
5686 if (!list_empty(&tsk
->cg_list
)) {
5687 spin_lock_irq(&css_set_lock
);
5688 css_set_move_task(tsk
, cset
, NULL
, false);
5690 spin_unlock_irq(&css_set_lock
);
5695 /* see cgroup_post_fork() for details */
5696 do_each_subsys_mask(ss
, i
, have_exit_callback
) {
5698 } while_each_subsys_mask();
5701 void cgroup_free(struct task_struct
*task
)
5703 struct css_set
*cset
= task_css_set(task
);
5704 struct cgroup_subsys
*ss
;
5707 do_each_subsys_mask(ss
, ssid
, have_free_callback
) {
5709 } while_each_subsys_mask();
5714 static int __init
cgroup_disable(char *str
)
5716 struct cgroup_subsys
*ss
;
5720 while ((token
= strsep(&str
, ",")) != NULL
) {
5724 for_each_subsys(ss
, i
) {
5725 if (strcmp(token
, ss
->name
) &&
5726 strcmp(token
, ss
->legacy_name
))
5728 cgroup_disable_mask
|= 1 << i
;
5733 __setup("cgroup_disable=", cgroup_disable
);
5736 * css_tryget_online_from_dir - get corresponding css from a cgroup dentry
5737 * @dentry: directory dentry of interest
5738 * @ss: subsystem of interest
5740 * If @dentry is a directory for a cgroup which has @ss enabled on it, try
5741 * to get the corresponding css and return it. If such css doesn't exist
5742 * or can't be pinned, an ERR_PTR value is returned.
5744 struct cgroup_subsys_state
*css_tryget_online_from_dir(struct dentry
*dentry
,
5745 struct cgroup_subsys
*ss
)
5747 struct kernfs_node
*kn
= kernfs_node_from_dentry(dentry
);
5748 struct file_system_type
*s_type
= dentry
->d_sb
->s_type
;
5749 struct cgroup_subsys_state
*css
= NULL
;
5750 struct cgroup
*cgrp
;
5752 /* is @dentry a cgroup dir? */
5753 if ((s_type
!= &cgroup_fs_type
&& s_type
!= &cgroup2_fs_type
) ||
5754 !kn
|| kernfs_type(kn
) != KERNFS_DIR
)
5755 return ERR_PTR(-EBADF
);
5760 * This path doesn't originate from kernfs and @kn could already
5761 * have been or be removed at any point. @kn->priv is RCU
5762 * protected for this access. See css_release_work_fn() for details.
5764 cgrp
= rcu_dereference(*(void __rcu __force
**)&kn
->priv
);
5766 css
= cgroup_css(cgrp
, ss
);
5768 if (!css
|| !css_tryget_online(css
))
5769 css
= ERR_PTR(-ENOENT
);
5776 * css_from_id - lookup css by id
5777 * @id: the cgroup id
5778 * @ss: cgroup subsys to be looked into
5780 * Returns the css if there's valid one with @id, otherwise returns NULL.
5781 * Should be called under rcu_read_lock().
5783 struct cgroup_subsys_state
*css_from_id(int id
, struct cgroup_subsys
*ss
)
5785 WARN_ON_ONCE(!rcu_read_lock_held());
5786 return idr_find(&ss
->css_idr
, id
);
5790 * cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path
5791 * @path: path on the default hierarchy
5793 * Find the cgroup at @path on the default hierarchy, increment its
5794 * reference count and return it. Returns pointer to the found cgroup on
5795 * success, ERR_PTR(-ENOENT) if @path doens't exist and ERR_PTR(-ENOTDIR)
5796 * if @path points to a non-directory.
5798 struct cgroup
*cgroup_get_from_path(const char *path
)
5800 struct kernfs_node
*kn
;
5801 struct cgroup
*cgrp
;
5803 mutex_lock(&cgroup_mutex
);
5805 kn
= kernfs_walk_and_get(cgrp_dfl_root
.cgrp
.kn
, path
);
5807 if (kernfs_type(kn
) == KERNFS_DIR
) {
5809 cgroup_get_live(cgrp
);
5811 cgrp
= ERR_PTR(-ENOTDIR
);
5815 cgrp
= ERR_PTR(-ENOENT
);
5818 mutex_unlock(&cgroup_mutex
);
5821 EXPORT_SYMBOL_GPL(cgroup_get_from_path
);
5824 * cgroup_get_from_fd - get a cgroup pointer from a fd
5825 * @fd: fd obtained by open(cgroup2_dir)
5827 * Find the cgroup from a fd which should be obtained
5828 * by opening a cgroup directory. Returns a pointer to the
5829 * cgroup on success. ERR_PTR is returned if the cgroup
5832 struct cgroup
*cgroup_get_from_fd(int fd
)
5834 struct cgroup_subsys_state
*css
;
5835 struct cgroup
*cgrp
;
5840 return ERR_PTR(-EBADF
);
5842 css
= css_tryget_online_from_dir(f
->f_path
.dentry
, NULL
);
5845 return ERR_CAST(css
);
5848 if (!cgroup_on_dfl(cgrp
)) {
5850 return ERR_PTR(-EBADF
);
5855 EXPORT_SYMBOL_GPL(cgroup_get_from_fd
);
5858 * sock->sk_cgrp_data handling. For more info, see sock_cgroup_data
5859 * definition in cgroup-defs.h.
5861 #ifdef CONFIG_SOCK_CGROUP_DATA
5863 #if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
5865 DEFINE_SPINLOCK(cgroup_sk_update_lock
);
5866 static bool cgroup_sk_alloc_disabled __read_mostly
;
5868 void cgroup_sk_alloc_disable(void)
5870 if (cgroup_sk_alloc_disabled
)
5872 pr_info("cgroup: disabling cgroup2 socket matching due to net_prio or net_cls activation\n");
5873 cgroup_sk_alloc_disabled
= true;
5878 #define cgroup_sk_alloc_disabled false
5882 void cgroup_sk_alloc(struct sock_cgroup_data
*skcd
)
5884 if (cgroup_sk_alloc_disabled
)
5887 /* Socket clone path */
5890 * We might be cloning a socket which is left in an empty
5891 * cgroup and the cgroup might have already been rmdir'd.
5892 * Don't use cgroup_get_live().
5894 cgroup_get(sock_cgroup_ptr(skcd
));
5901 struct css_set
*cset
;
5903 cset
= task_css_set(current
);
5904 if (likely(cgroup_tryget(cset
->dfl_cgrp
))) {
5905 skcd
->val
= (unsigned long)cset
->dfl_cgrp
;
5914 void cgroup_sk_free(struct sock_cgroup_data
*skcd
)
5916 cgroup_put(sock_cgroup_ptr(skcd
));
5919 #endif /* CONFIG_SOCK_CGROUP_DATA */
5921 #ifdef CONFIG_CGROUP_BPF
5922 int cgroup_bpf_attach(struct cgroup
*cgrp
, struct bpf_prog
*prog
,
5923 enum bpf_attach_type type
, u32 flags
)
5927 mutex_lock(&cgroup_mutex
);
5928 ret
= __cgroup_bpf_attach(cgrp
, prog
, type
, flags
);
5929 mutex_unlock(&cgroup_mutex
);
5932 int cgroup_bpf_detach(struct cgroup
*cgrp
, struct bpf_prog
*prog
,
5933 enum bpf_attach_type type
, u32 flags
)
5937 mutex_lock(&cgroup_mutex
);
5938 ret
= __cgroup_bpf_detach(cgrp
, prog
, type
, flags
);
5939 mutex_unlock(&cgroup_mutex
);
5942 int cgroup_bpf_query(struct cgroup
*cgrp
, const union bpf_attr
*attr
,
5943 union bpf_attr __user
*uattr
)
5947 mutex_lock(&cgroup_mutex
);
5948 ret
= __cgroup_bpf_query(cgrp
, attr
, uattr
);
5949 mutex_unlock(&cgroup_mutex
);
5952 #endif /* CONFIG_CGROUP_BPF */
5955 static ssize_t
show_delegatable_files(struct cftype
*files
, char *buf
,
5956 ssize_t size
, const char *prefix
)
5961 for (cft
= files
; cft
&& cft
->name
[0] != '\0'; cft
++) {
5962 if (!(cft
->flags
& CFTYPE_NS_DELEGATABLE
))
5966 ret
+= snprintf(buf
+ ret
, size
- ret
, "%s.", prefix
);
5968 ret
+= snprintf(buf
+ ret
, size
- ret
, "%s\n", cft
->name
);
5970 if (unlikely(ret
>= size
)) {
5979 static ssize_t
delegate_show(struct kobject
*kobj
, struct kobj_attribute
*attr
,
5982 struct cgroup_subsys
*ss
;
5986 ret
= show_delegatable_files(cgroup_base_files
, buf
, PAGE_SIZE
- ret
,
5989 for_each_subsys(ss
, ssid
)
5990 ret
+= show_delegatable_files(ss
->dfl_cftypes
, buf
+ ret
,
5992 cgroup_subsys_name
[ssid
]);
5996 static struct kobj_attribute cgroup_delegate_attr
= __ATTR_RO(delegate
);
5998 static ssize_t
features_show(struct kobject
*kobj
, struct kobj_attribute
*attr
,
6001 return snprintf(buf
, PAGE_SIZE
, "nsdelegate\n");
6003 static struct kobj_attribute cgroup_features_attr
= __ATTR_RO(features
);
6005 static struct attribute
*cgroup_sysfs_attrs
[] = {
6006 &cgroup_delegate_attr
.attr
,
6007 &cgroup_features_attr
.attr
,
6011 static const struct attribute_group cgroup_sysfs_attr_group
= {
6012 .attrs
= cgroup_sysfs_attrs
,
6016 static int __init
cgroup_sysfs_init(void)
6018 return sysfs_create_group(kernel_kobj
, &cgroup_sysfs_attr_group
);
6020 subsys_initcall(cgroup_sysfs_init
);
6021 #endif /* CONFIG_SYSFS */