4 * Copyright (C) 2008 ARM Limited
5 * Written by Catalin Marinas <catalin.marinas@arm.com>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 * For more information on the algorithm and kmemleak usage, please see
22 * Documentation/kmemleak.txt.
27 * The following locks and mutexes are used by kmemleak:
29 * - kmemleak_lock (rwlock): protects the object_list modifications and
30 * accesses to the object_tree_root. The object_list is the main list
31 * holding the metadata (struct kmemleak_object) for the allocated memory
32 * blocks. The object_tree_root is a red black tree used to look-up
33 * metadata based on a pointer to the corresponding memory block. The
34 * kmemleak_object structures are added to the object_list and
35 * object_tree_root in the create_object() function called from the
36 * kmemleak_alloc() callback and removed in delete_object() called from the
37 * kmemleak_free() callback
38 * - kmemleak_object.lock (spinlock): protects a kmemleak_object. Accesses to
39 * the metadata (e.g. count) are protected by this lock. Note that some
40 * members of this structure may be protected by other means (atomic or
41 * kmemleak_lock). This lock is also held when scanning the corresponding
42 * memory block to avoid the kernel freeing it via the kmemleak_free()
43 * callback. This is less heavyweight than holding a global lock like
44 * kmemleak_lock during scanning
45 * - scan_mutex (mutex): ensures that only one thread may scan the memory for
46 * unreferenced objects at a time. The gray_list contains the objects which
47 * are already referenced or marked as false positives and need to be
48 * scanned. This list is only modified during a scanning episode when the
49 * scan_mutex is held. At the end of a scan, the gray_list is always empty.
50 * Note that the kmemleak_object.use_count is incremented when an object is
51 * added to the gray_list and therefore cannot be freed. This mutex also
52 * prevents multiple users of the "kmemleak" debugfs file together with
53 * modifications to the memory scanning parameters including the scan_thread
56 * Locks and mutexes should only be acquired/nested in the following order:
58 * scan_mutex -> object->lock -> other_object->lock (SINGLE_DEPTH_NESTING)
61 * The kmemleak_object structures have a use_count incremented or decremented
62 * using the get_object()/put_object() functions. When the use_count becomes
63 * 0, this count can no longer be incremented and put_object() schedules the
64 * kmemleak_object freeing via an RCU callback. All calls to the get_object()
65 * function must be protected by rcu_read_lock() to avoid accessing a freed
69 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
71 #include <linux/init.h>
72 #include <linux/kernel.h>
73 #include <linux/list.h>
74 #include <linux/sched.h>
75 #include <linux/jiffies.h>
76 #include <linux/delay.h>
77 #include <linux/export.h>
78 #include <linux/kthread.h>
79 #include <linux/rbtree.h>
81 #include <linux/debugfs.h>
82 #include <linux/seq_file.h>
83 #include <linux/cpumask.h>
84 #include <linux/spinlock.h>
85 #include <linux/mutex.h>
86 #include <linux/rcupdate.h>
87 #include <linux/stacktrace.h>
88 #include <linux/cache.h>
89 #include <linux/percpu.h>
90 #include <linux/hardirq.h>
91 #include <linux/mmzone.h>
92 #include <linux/slab.h>
93 #include <linux/thread_info.h>
94 #include <linux/err.h>
95 #include <linux/uaccess.h>
96 #include <linux/string.h>
97 #include <linux/nodemask.h>
99 #include <linux/workqueue.h>
100 #include <linux/crc32.h>
102 #include <asm/sections.h>
103 #include <asm/processor.h>
104 #include <linux/atomic.h>
106 #include <linux/kasan.h>
107 #include <linux/kmemcheck.h>
108 #include <linux/kmemleak.h>
109 #include <linux/memory_hotplug.h>
112 * Kmemleak configuration and common defines.
114 #define MAX_TRACE 16 /* stack trace length */
115 #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
116 #define SECS_FIRST_SCAN 60 /* delay before the first scan */
117 #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
118 #define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
120 #define BYTES_PER_POINTER sizeof(void *)
122 /* GFP bitmask for kmemleak internal allocations */
123 #define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC | \
124 __GFP_NOACCOUNT)) | \
125 __GFP_NORETRY | __GFP_NOMEMALLOC | \
128 /* scanning area inside a memory block */
129 struct kmemleak_scan_area
{
130 struct hlist_node node
;
135 #define KMEMLEAK_GREY 0
136 #define KMEMLEAK_BLACK -1
139 * Structure holding the metadata for each allocated memory block.
140 * Modifications to such objects should be made while holding the
141 * object->lock. Insertions or deletions from object_list, gray_list or
142 * rb_node are already protected by the corresponding locks or mutex (see
143 * the notes on locking above). These objects are reference-counted
144 * (use_count) and freed using the RCU mechanism.
146 struct kmemleak_object
{
148 unsigned long flags
; /* object status flags */
149 struct list_head object_list
;
150 struct list_head gray_list
;
151 struct rb_node rb_node
;
152 struct rcu_head rcu
; /* object_list lockless traversal */
153 /* object usage count; object freed when use_count == 0 */
155 unsigned long pointer
;
157 /* minimum number of a pointers found before it is considered leak */
159 /* the total number of pointers found pointing to this object */
161 /* checksum for detecting modified objects */
163 /* memory ranges to be scanned inside an object (empty for all) */
164 struct hlist_head area_list
;
165 unsigned long trace
[MAX_TRACE
];
166 unsigned int trace_len
;
167 unsigned long jiffies
; /* creation timestamp */
168 pid_t pid
; /* pid of the current task */
169 char comm
[TASK_COMM_LEN
]; /* executable name */
172 /* flag representing the memory block allocation status */
173 #define OBJECT_ALLOCATED (1 << 0)
174 /* flag set after the first reporting of an unreference object */
175 #define OBJECT_REPORTED (1 << 1)
176 /* flag set to not scan the object */
177 #define OBJECT_NO_SCAN (1 << 2)
179 /* number of bytes to print per line; must be 16 or 32 */
180 #define HEX_ROW_SIZE 16
181 /* number of bytes to print at a time (1, 2, 4, 8) */
182 #define HEX_GROUP_SIZE 1
183 /* include ASCII after the hex output */
185 /* max number of lines to be printed */
186 #define HEX_MAX_LINES 2
188 /* the list of all allocated objects */
189 static LIST_HEAD(object_list
);
190 /* the list of gray-colored objects (see color_gray comment below) */
191 static LIST_HEAD(gray_list
);
192 /* search tree for object boundaries */
193 static struct rb_root object_tree_root
= RB_ROOT
;
194 /* rw_lock protecting the access to object_list and object_tree_root */
195 static DEFINE_RWLOCK(kmemleak_lock
);
197 /* allocation caches for kmemleak internal data */
198 static struct kmem_cache
*object_cache
;
199 static struct kmem_cache
*scan_area_cache
;
201 /* set if tracing memory operations is enabled */
202 static int kmemleak_enabled
;
203 /* same as above but only for the kmemleak_free() callback */
204 static int kmemleak_free_enabled
;
205 /* set in the late_initcall if there were no errors */
206 static int kmemleak_initialized
;
207 /* enables or disables early logging of the memory operations */
208 static int kmemleak_early_log
= 1;
209 /* set if a kmemleak warning was issued */
210 static int kmemleak_warning
;
211 /* set if a fatal kmemleak error has occurred */
212 static int kmemleak_error
;
214 /* minimum and maximum address that may be valid pointers */
215 static unsigned long min_addr
= ULONG_MAX
;
216 static unsigned long max_addr
;
218 static struct task_struct
*scan_thread
;
219 /* used to avoid reporting of recently allocated objects */
220 static unsigned long jiffies_min_age
;
221 static unsigned long jiffies_last_scan
;
222 /* delay between automatic memory scannings */
223 static signed long jiffies_scan_wait
;
224 /* enables or disables the task stacks scanning */
225 static int kmemleak_stack_scan
= 1;
226 /* protects the memory scanning, parameters and debug/kmemleak file access */
227 static DEFINE_MUTEX(scan_mutex
);
228 /* setting kmemleak=on, will set this var, skipping the disable */
229 static int kmemleak_skip_disable
;
230 /* If there are leaks that can be reported */
231 static bool kmemleak_found_leaks
;
234 * Early object allocation/freeing logging. Kmemleak is initialized after the
235 * kernel allocator. However, both the kernel allocator and kmemleak may
236 * allocate memory blocks which need to be tracked. Kmemleak defines an
237 * arbitrary buffer to hold the allocation/freeing information before it is
241 /* kmemleak operation type for early logging */
244 KMEMLEAK_ALLOC_PERCPU
,
247 KMEMLEAK_FREE_PERCPU
,
255 * Structure holding the information passed to kmemleak callbacks during the
259 int op_type
; /* kmemleak operation type */
260 const void *ptr
; /* allocated/freed memory block */
261 size_t size
; /* memory block size */
262 int min_count
; /* minimum reference count */
263 unsigned long trace
[MAX_TRACE
]; /* stack trace */
264 unsigned int trace_len
; /* stack trace length */
267 /* early logging buffer and current position */
268 static struct early_log
269 early_log
[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE
] __initdata
;
270 static int crt_early_log __initdata
;
272 static void kmemleak_disable(void);
275 * Print a warning and dump the stack trace.
277 #define kmemleak_warn(x...) do { \
280 kmemleak_warning = 1; \
284 * Macro invoked when a serious kmemleak condition occurred and cannot be
285 * recovered from. Kmemleak will be disabled and further allocation/freeing
286 * tracing no longer available.
288 #define kmemleak_stop(x...) do { \
290 kmemleak_disable(); \
294 * Printing of the objects hex dump to the seq file. The number of lines to be
295 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
296 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
297 * with the object->lock held.
299 static void hex_dump_object(struct seq_file
*seq
,
300 struct kmemleak_object
*object
)
302 const u8
*ptr
= (const u8
*)object
->pointer
;
303 int i
, len
, remaining
;
304 unsigned char linebuf
[HEX_ROW_SIZE
* 5];
306 /* limit the number of lines to HEX_MAX_LINES */
308 min(object
->size
, (size_t)(HEX_MAX_LINES
* HEX_ROW_SIZE
));
310 seq_printf(seq
, " hex dump (first %d bytes):\n", len
);
311 for (i
= 0; i
< len
; i
+= HEX_ROW_SIZE
) {
312 int linelen
= min(remaining
, HEX_ROW_SIZE
);
314 remaining
-= HEX_ROW_SIZE
;
315 hex_dump_to_buffer(ptr
+ i
, linelen
, HEX_ROW_SIZE
,
316 HEX_GROUP_SIZE
, linebuf
, sizeof(linebuf
),
318 seq_printf(seq
, " %s\n", linebuf
);
323 * Object colors, encoded with count and min_count:
324 * - white - orphan object, not enough references to it (count < min_count)
325 * - gray - not orphan, not marked as false positive (min_count == 0) or
326 * sufficient references to it (count >= min_count)
327 * - black - ignore, it doesn't contain references (e.g. text section)
328 * (min_count == -1). No function defined for this color.
329 * Newly created objects don't have any color assigned (object->count == -1)
330 * before the next memory scan when they become white.
332 static bool color_white(const struct kmemleak_object
*object
)
334 return object
->count
!= KMEMLEAK_BLACK
&&
335 object
->count
< object
->min_count
;
338 static bool color_gray(const struct kmemleak_object
*object
)
340 return object
->min_count
!= KMEMLEAK_BLACK
&&
341 object
->count
>= object
->min_count
;
345 * Objects are considered unreferenced only if their color is white, they have
346 * not be deleted and have a minimum age to avoid false positives caused by
347 * pointers temporarily stored in CPU registers.
349 static bool unreferenced_object(struct kmemleak_object
*object
)
351 return (color_white(object
) && object
->flags
& OBJECT_ALLOCATED
) &&
352 time_before_eq(object
->jiffies
+ jiffies_min_age
,
357 * Printing of the unreferenced objects information to the seq file. The
358 * print_unreferenced function must be called with the object->lock held.
360 static void print_unreferenced(struct seq_file
*seq
,
361 struct kmemleak_object
*object
)
364 unsigned int msecs_age
= jiffies_to_msecs(jiffies
- object
->jiffies
);
366 seq_printf(seq
, "unreferenced object 0x%08lx (size %zu):\n",
367 object
->pointer
, object
->size
);
368 seq_printf(seq
, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
369 object
->comm
, object
->pid
, object
->jiffies
,
370 msecs_age
/ 1000, msecs_age
% 1000);
371 hex_dump_object(seq
, object
);
372 seq_printf(seq
, " backtrace:\n");
374 for (i
= 0; i
< object
->trace_len
; i
++) {
375 void *ptr
= (void *)object
->trace
[i
];
376 seq_printf(seq
, " [<%p>] %pS\n", ptr
, ptr
);
381 * Print the kmemleak_object information. This function is used mainly for
382 * debugging special cases when kmemleak operations. It must be called with
383 * the object->lock held.
385 static void dump_object_info(struct kmemleak_object
*object
)
387 struct stack_trace trace
;
389 trace
.nr_entries
= object
->trace_len
;
390 trace
.entries
= object
->trace
;
392 pr_notice("Object 0x%08lx (size %zu):\n",
393 object
->pointer
, object
->size
);
394 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
395 object
->comm
, object
->pid
, object
->jiffies
);
396 pr_notice(" min_count = %d\n", object
->min_count
);
397 pr_notice(" count = %d\n", object
->count
);
398 pr_notice(" flags = 0x%lx\n", object
->flags
);
399 pr_notice(" checksum = %u\n", object
->checksum
);
400 pr_notice(" backtrace:\n");
401 print_stack_trace(&trace
, 4);
405 * Look-up a memory block metadata (kmemleak_object) in the object search
406 * tree based on a pointer value. If alias is 0, only values pointing to the
407 * beginning of the memory block are allowed. The kmemleak_lock must be held
408 * when calling this function.
410 static struct kmemleak_object
*lookup_object(unsigned long ptr
, int alias
)
412 struct rb_node
*rb
= object_tree_root
.rb_node
;
415 struct kmemleak_object
*object
=
416 rb_entry(rb
, struct kmemleak_object
, rb_node
);
417 if (ptr
< object
->pointer
)
418 rb
= object
->rb_node
.rb_left
;
419 else if (object
->pointer
+ object
->size
<= ptr
)
420 rb
= object
->rb_node
.rb_right
;
421 else if (object
->pointer
== ptr
|| alias
)
424 kmemleak_warn("Found object by alias at 0x%08lx\n",
426 dump_object_info(object
);
434 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
435 * that once an object's use_count reached 0, the RCU freeing was already
436 * registered and the object should no longer be used. This function must be
437 * called under the protection of rcu_read_lock().
439 static int get_object(struct kmemleak_object
*object
)
441 return atomic_inc_not_zero(&object
->use_count
);
445 * RCU callback to free a kmemleak_object.
447 static void free_object_rcu(struct rcu_head
*rcu
)
449 struct hlist_node
*tmp
;
450 struct kmemleak_scan_area
*area
;
451 struct kmemleak_object
*object
=
452 container_of(rcu
, struct kmemleak_object
, rcu
);
455 * Once use_count is 0 (guaranteed by put_object), there is no other
456 * code accessing this object, hence no need for locking.
458 hlist_for_each_entry_safe(area
, tmp
, &object
->area_list
, node
) {
459 hlist_del(&area
->node
);
460 kmem_cache_free(scan_area_cache
, area
);
462 kmem_cache_free(object_cache
, object
);
466 * Decrement the object use_count. Once the count is 0, free the object using
467 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
468 * delete_object() path, the delayed RCU freeing ensures that there is no
469 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
472 static void put_object(struct kmemleak_object
*object
)
474 if (!atomic_dec_and_test(&object
->use_count
))
477 /* should only get here after delete_object was called */
478 WARN_ON(object
->flags
& OBJECT_ALLOCATED
);
480 call_rcu(&object
->rcu
, free_object_rcu
);
484 * Look up an object in the object search tree and increase its use_count.
486 static struct kmemleak_object
*find_and_get_object(unsigned long ptr
, int alias
)
489 struct kmemleak_object
*object
= NULL
;
492 read_lock_irqsave(&kmemleak_lock
, flags
);
493 if (ptr
>= min_addr
&& ptr
< max_addr
)
494 object
= lookup_object(ptr
, alias
);
495 read_unlock_irqrestore(&kmemleak_lock
, flags
);
497 /* check whether the object is still available */
498 if (object
&& !get_object(object
))
506 * Look up an object in the object search tree and remove it from both
507 * object_tree_root and object_list. The returned object's use_count should be
508 * at least 1, as initially set by create_object().
510 static struct kmemleak_object
*find_and_remove_object(unsigned long ptr
, int alias
)
513 struct kmemleak_object
*object
;
515 write_lock_irqsave(&kmemleak_lock
, flags
);
516 object
= lookup_object(ptr
, alias
);
518 rb_erase(&object
->rb_node
, &object_tree_root
);
519 list_del_rcu(&object
->object_list
);
521 write_unlock_irqrestore(&kmemleak_lock
, flags
);
527 * Save stack trace to the given array of MAX_TRACE size.
529 static int __save_stack_trace(unsigned long *trace
)
531 struct stack_trace stack_trace
;
533 stack_trace
.max_entries
= MAX_TRACE
;
534 stack_trace
.nr_entries
= 0;
535 stack_trace
.entries
= trace
;
536 stack_trace
.skip
= 2;
537 save_stack_trace(&stack_trace
);
539 return stack_trace
.nr_entries
;
543 * Create the metadata (struct kmemleak_object) corresponding to an allocated
544 * memory block and add it to the object_list and object_tree_root.
546 static struct kmemleak_object
*create_object(unsigned long ptr
, size_t size
,
547 int min_count
, gfp_t gfp
)
550 struct kmemleak_object
*object
, *parent
;
551 struct rb_node
**link
, *rb_parent
;
553 object
= kmem_cache_alloc(object_cache
, gfp_kmemleak_mask(gfp
));
555 pr_warning("Cannot allocate a kmemleak_object structure\n");
560 INIT_LIST_HEAD(&object
->object_list
);
561 INIT_LIST_HEAD(&object
->gray_list
);
562 INIT_HLIST_HEAD(&object
->area_list
);
563 spin_lock_init(&object
->lock
);
564 atomic_set(&object
->use_count
, 1);
565 object
->flags
= OBJECT_ALLOCATED
;
566 object
->pointer
= ptr
;
568 object
->min_count
= min_count
;
569 object
->count
= 0; /* white color initially */
570 object
->jiffies
= jiffies
;
571 object
->checksum
= 0;
573 /* task information */
576 strncpy(object
->comm
, "hardirq", sizeof(object
->comm
));
577 } else if (in_softirq()) {
579 strncpy(object
->comm
, "softirq", sizeof(object
->comm
));
581 object
->pid
= current
->pid
;
583 * There is a small chance of a race with set_task_comm(),
584 * however using get_task_comm() here may cause locking
585 * dependency issues with current->alloc_lock. In the worst
586 * case, the command line is not correct.
588 strncpy(object
->comm
, current
->comm
, sizeof(object
->comm
));
591 /* kernel backtrace */
592 object
->trace_len
= __save_stack_trace(object
->trace
);
594 write_lock_irqsave(&kmemleak_lock
, flags
);
596 min_addr
= min(min_addr
, ptr
);
597 max_addr
= max(max_addr
, ptr
+ size
);
598 link
= &object_tree_root
.rb_node
;
602 parent
= rb_entry(rb_parent
, struct kmemleak_object
, rb_node
);
603 if (ptr
+ size
<= parent
->pointer
)
604 link
= &parent
->rb_node
.rb_left
;
605 else if (parent
->pointer
+ parent
->size
<= ptr
)
606 link
= &parent
->rb_node
.rb_right
;
608 kmemleak_stop("Cannot insert 0x%lx into the object "
609 "search tree (overlaps existing)\n",
612 * No need for parent->lock here since "parent" cannot
613 * be freed while the kmemleak_lock is held.
615 dump_object_info(parent
);
616 kmem_cache_free(object_cache
, object
);
621 rb_link_node(&object
->rb_node
, rb_parent
, link
);
622 rb_insert_color(&object
->rb_node
, &object_tree_root
);
624 list_add_tail_rcu(&object
->object_list
, &object_list
);
626 write_unlock_irqrestore(&kmemleak_lock
, flags
);
631 * Mark the object as not allocated and schedule RCU freeing via put_object().
633 static void __delete_object(struct kmemleak_object
*object
)
637 WARN_ON(!(object
->flags
& OBJECT_ALLOCATED
));
638 WARN_ON(atomic_read(&object
->use_count
) < 1);
641 * Locking here also ensures that the corresponding memory block
642 * cannot be freed when it is being scanned.
644 spin_lock_irqsave(&object
->lock
, flags
);
645 object
->flags
&= ~OBJECT_ALLOCATED
;
646 spin_unlock_irqrestore(&object
->lock
, flags
);
651 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
654 static void delete_object_full(unsigned long ptr
)
656 struct kmemleak_object
*object
;
658 object
= find_and_remove_object(ptr
, 0);
661 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
666 __delete_object(object
);
670 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
671 * delete it. If the memory block is partially freed, the function may create
672 * additional metadata for the remaining parts of the block.
674 static void delete_object_part(unsigned long ptr
, size_t size
)
676 struct kmemleak_object
*object
;
677 unsigned long start
, end
;
679 object
= find_and_remove_object(ptr
, 1);
682 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
683 "(size %zu)\n", ptr
, size
);
689 * Create one or two objects that may result from the memory block
690 * split. Note that partial freeing is only done by free_bootmem() and
691 * this happens before kmemleak_init() is called. The path below is
692 * only executed during early log recording in kmemleak_init(), so
693 * GFP_KERNEL is enough.
695 start
= object
->pointer
;
696 end
= object
->pointer
+ object
->size
;
698 create_object(start
, ptr
- start
, object
->min_count
,
700 if (ptr
+ size
< end
)
701 create_object(ptr
+ size
, end
- ptr
- size
, object
->min_count
,
704 __delete_object(object
);
707 static void __paint_it(struct kmemleak_object
*object
, int color
)
709 object
->min_count
= color
;
710 if (color
== KMEMLEAK_BLACK
)
711 object
->flags
|= OBJECT_NO_SCAN
;
714 static void paint_it(struct kmemleak_object
*object
, int color
)
718 spin_lock_irqsave(&object
->lock
, flags
);
719 __paint_it(object
, color
);
720 spin_unlock_irqrestore(&object
->lock
, flags
);
723 static void paint_ptr(unsigned long ptr
, int color
)
725 struct kmemleak_object
*object
;
727 object
= find_and_get_object(ptr
, 0);
729 kmemleak_warn("Trying to color unknown object "
730 "at 0x%08lx as %s\n", ptr
,
731 (color
== KMEMLEAK_GREY
) ? "Grey" :
732 (color
== KMEMLEAK_BLACK
) ? "Black" : "Unknown");
735 paint_it(object
, color
);
740 * Mark an object permanently as gray-colored so that it can no longer be
741 * reported as a leak. This is used in general to mark a false positive.
743 static void make_gray_object(unsigned long ptr
)
745 paint_ptr(ptr
, KMEMLEAK_GREY
);
749 * Mark the object as black-colored so that it is ignored from scans and
752 static void make_black_object(unsigned long ptr
)
754 paint_ptr(ptr
, KMEMLEAK_BLACK
);
758 * Add a scanning area to the object. If at least one such area is added,
759 * kmemleak will only scan these ranges rather than the whole memory block.
761 static void add_scan_area(unsigned long ptr
, size_t size
, gfp_t gfp
)
764 struct kmemleak_object
*object
;
765 struct kmemleak_scan_area
*area
;
767 object
= find_and_get_object(ptr
, 1);
769 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
774 area
= kmem_cache_alloc(scan_area_cache
, gfp_kmemleak_mask(gfp
));
776 pr_warning("Cannot allocate a scan area\n");
780 spin_lock_irqsave(&object
->lock
, flags
);
781 if (size
== SIZE_MAX
) {
782 size
= object
->pointer
+ object
->size
- ptr
;
783 } else if (ptr
+ size
> object
->pointer
+ object
->size
) {
784 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr
);
785 dump_object_info(object
);
786 kmem_cache_free(scan_area_cache
, area
);
790 INIT_HLIST_NODE(&area
->node
);
794 hlist_add_head(&area
->node
, &object
->area_list
);
796 spin_unlock_irqrestore(&object
->lock
, flags
);
802 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
803 * pointer. Such object will not be scanned by kmemleak but references to it
806 static void object_no_scan(unsigned long ptr
)
809 struct kmemleak_object
*object
;
811 object
= find_and_get_object(ptr
, 0);
813 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr
);
817 spin_lock_irqsave(&object
->lock
, flags
);
818 object
->flags
|= OBJECT_NO_SCAN
;
819 spin_unlock_irqrestore(&object
->lock
, flags
);
824 * Log an early kmemleak_* call to the early_log buffer. These calls will be
825 * processed later once kmemleak is fully initialized.
827 static void __init
log_early(int op_type
, const void *ptr
, size_t size
,
831 struct early_log
*log
;
833 if (kmemleak_error
) {
834 /* kmemleak stopped recording, just count the requests */
839 if (crt_early_log
>= ARRAY_SIZE(early_log
)) {
845 * There is no need for locking since the kernel is still in UP mode
846 * at this stage. Disabling the IRQs is enough.
848 local_irq_save(flags
);
849 log
= &early_log
[crt_early_log
];
850 log
->op_type
= op_type
;
853 log
->min_count
= min_count
;
854 log
->trace_len
= __save_stack_trace(log
->trace
);
856 local_irq_restore(flags
);
860 * Log an early allocated block and populate the stack trace.
862 static void early_alloc(struct early_log
*log
)
864 struct kmemleak_object
*object
;
868 if (!kmemleak_enabled
|| !log
->ptr
|| IS_ERR(log
->ptr
))
872 * RCU locking needed to ensure object is not freed via put_object().
875 object
= create_object((unsigned long)log
->ptr
, log
->size
,
876 log
->min_count
, GFP_ATOMIC
);
879 spin_lock_irqsave(&object
->lock
, flags
);
880 for (i
= 0; i
< log
->trace_len
; i
++)
881 object
->trace
[i
] = log
->trace
[i
];
882 object
->trace_len
= log
->trace_len
;
883 spin_unlock_irqrestore(&object
->lock
, flags
);
889 * Log an early allocated block and populate the stack trace.
891 static void early_alloc_percpu(struct early_log
*log
)
894 const void __percpu
*ptr
= log
->ptr
;
896 for_each_possible_cpu(cpu
) {
897 log
->ptr
= per_cpu_ptr(ptr
, cpu
);
903 * kmemleak_alloc - register a newly allocated object
904 * @ptr: pointer to beginning of the object
905 * @size: size of the object
906 * @min_count: minimum number of references to this object. If during memory
907 * scanning a number of references less than @min_count is found,
908 * the object is reported as a memory leak. If @min_count is 0,
909 * the object is never reported as a leak. If @min_count is -1,
910 * the object is ignored (not scanned and not reported as a leak)
911 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
913 * This function is called from the kernel allocators when a new object
914 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
916 void __ref
kmemleak_alloc(const void *ptr
, size_t size
, int min_count
,
919 pr_debug("%s(0x%p, %zu, %d)\n", __func__
, ptr
, size
, min_count
);
921 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
922 create_object((unsigned long)ptr
, size
, min_count
, gfp
);
923 else if (kmemleak_early_log
)
924 log_early(KMEMLEAK_ALLOC
, ptr
, size
, min_count
);
926 EXPORT_SYMBOL_GPL(kmemleak_alloc
);
929 * kmemleak_alloc_percpu - register a newly allocated __percpu object
930 * @ptr: __percpu pointer to beginning of the object
931 * @size: size of the object
933 * This function is called from the kernel percpu allocator when a new object
934 * (memory block) is allocated (alloc_percpu). It assumes GFP_KERNEL
937 void __ref
kmemleak_alloc_percpu(const void __percpu
*ptr
, size_t size
)
941 pr_debug("%s(0x%p, %zu)\n", __func__
, ptr
, size
);
944 * Percpu allocations are only scanned and not reported as leaks
945 * (min_count is set to 0).
947 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
948 for_each_possible_cpu(cpu
)
949 create_object((unsigned long)per_cpu_ptr(ptr
, cpu
),
950 size
, 0, GFP_KERNEL
);
951 else if (kmemleak_early_log
)
952 log_early(KMEMLEAK_ALLOC_PERCPU
, ptr
, size
, 0);
954 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu
);
957 * kmemleak_free - unregister a previously registered object
958 * @ptr: pointer to beginning of the object
960 * This function is called from the kernel allocators when an object (memory
961 * block) is freed (kmem_cache_free, kfree, vfree etc.).
963 void __ref
kmemleak_free(const void *ptr
)
965 pr_debug("%s(0x%p)\n", __func__
, ptr
);
967 if (kmemleak_free_enabled
&& ptr
&& !IS_ERR(ptr
))
968 delete_object_full((unsigned long)ptr
);
969 else if (kmemleak_early_log
)
970 log_early(KMEMLEAK_FREE
, ptr
, 0, 0);
972 EXPORT_SYMBOL_GPL(kmemleak_free
);
975 * kmemleak_free_part - partially unregister a previously registered object
976 * @ptr: pointer to the beginning or inside the object. This also
977 * represents the start of the range to be freed
978 * @size: size to be unregistered
980 * This function is called when only a part of a memory block is freed
981 * (usually from the bootmem allocator).
983 void __ref
kmemleak_free_part(const void *ptr
, size_t size
)
985 pr_debug("%s(0x%p)\n", __func__
, ptr
);
987 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
988 delete_object_part((unsigned long)ptr
, size
);
989 else if (kmemleak_early_log
)
990 log_early(KMEMLEAK_FREE_PART
, ptr
, size
, 0);
992 EXPORT_SYMBOL_GPL(kmemleak_free_part
);
995 * kmemleak_free_percpu - unregister a previously registered __percpu object
996 * @ptr: __percpu pointer to beginning of the object
998 * This function is called from the kernel percpu allocator when an object
999 * (memory block) is freed (free_percpu).
1001 void __ref
kmemleak_free_percpu(const void __percpu
*ptr
)
1005 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1007 if (kmemleak_free_enabled
&& ptr
&& !IS_ERR(ptr
))
1008 for_each_possible_cpu(cpu
)
1009 delete_object_full((unsigned long)per_cpu_ptr(ptr
,
1011 else if (kmemleak_early_log
)
1012 log_early(KMEMLEAK_FREE_PERCPU
, ptr
, 0, 0);
1014 EXPORT_SYMBOL_GPL(kmemleak_free_percpu
);
1017 * kmemleak_update_trace - update object allocation stack trace
1018 * @ptr: pointer to beginning of the object
1020 * Override the object allocation stack trace for cases where the actual
1021 * allocation place is not always useful.
1023 void __ref
kmemleak_update_trace(const void *ptr
)
1025 struct kmemleak_object
*object
;
1026 unsigned long flags
;
1028 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1030 if (!kmemleak_enabled
|| IS_ERR_OR_NULL(ptr
))
1033 object
= find_and_get_object((unsigned long)ptr
, 1);
1036 kmemleak_warn("Updating stack trace for unknown object at %p\n",
1042 spin_lock_irqsave(&object
->lock
, flags
);
1043 object
->trace_len
= __save_stack_trace(object
->trace
);
1044 spin_unlock_irqrestore(&object
->lock
, flags
);
1048 EXPORT_SYMBOL(kmemleak_update_trace
);
1051 * kmemleak_not_leak - mark an allocated object as false positive
1052 * @ptr: pointer to beginning of the object
1054 * Calling this function on an object will cause the memory block to no longer
1055 * be reported as leak and always be scanned.
1057 void __ref
kmemleak_not_leak(const void *ptr
)
1059 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1061 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1062 make_gray_object((unsigned long)ptr
);
1063 else if (kmemleak_early_log
)
1064 log_early(KMEMLEAK_NOT_LEAK
, ptr
, 0, 0);
1066 EXPORT_SYMBOL(kmemleak_not_leak
);
1069 * kmemleak_ignore - ignore an allocated object
1070 * @ptr: pointer to beginning of the object
1072 * Calling this function on an object will cause the memory block to be
1073 * ignored (not scanned and not reported as a leak). This is usually done when
1074 * it is known that the corresponding block is not a leak and does not contain
1075 * any references to other allocated memory blocks.
1077 void __ref
kmemleak_ignore(const void *ptr
)
1079 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1081 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1082 make_black_object((unsigned long)ptr
);
1083 else if (kmemleak_early_log
)
1084 log_early(KMEMLEAK_IGNORE
, ptr
, 0, 0);
1086 EXPORT_SYMBOL(kmemleak_ignore
);
1089 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1090 * @ptr: pointer to beginning or inside the object. This also
1091 * represents the start of the scan area
1092 * @size: size of the scan area
1093 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1095 * This function is used when it is known that only certain parts of an object
1096 * contain references to other objects. Kmemleak will only scan these areas
1097 * reducing the number false negatives.
1099 void __ref
kmemleak_scan_area(const void *ptr
, size_t size
, gfp_t gfp
)
1101 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1103 if (kmemleak_enabled
&& ptr
&& size
&& !IS_ERR(ptr
))
1104 add_scan_area((unsigned long)ptr
, size
, gfp
);
1105 else if (kmemleak_early_log
)
1106 log_early(KMEMLEAK_SCAN_AREA
, ptr
, size
, 0);
1108 EXPORT_SYMBOL(kmemleak_scan_area
);
1111 * kmemleak_no_scan - do not scan an allocated object
1112 * @ptr: pointer to beginning of the object
1114 * This function notifies kmemleak not to scan the given memory block. Useful
1115 * in situations where it is known that the given object does not contain any
1116 * references to other objects. Kmemleak will not scan such objects reducing
1117 * the number of false negatives.
1119 void __ref
kmemleak_no_scan(const void *ptr
)
1121 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1123 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1124 object_no_scan((unsigned long)ptr
);
1125 else if (kmemleak_early_log
)
1126 log_early(KMEMLEAK_NO_SCAN
, ptr
, 0, 0);
1128 EXPORT_SYMBOL(kmemleak_no_scan
);
1131 * Update an object's checksum and return true if it was modified.
1133 static bool update_checksum(struct kmemleak_object
*object
)
1135 u32 old_csum
= object
->checksum
;
1137 if (!kmemcheck_is_obj_initialized(object
->pointer
, object
->size
))
1140 kasan_disable_current();
1141 object
->checksum
= crc32(0, (void *)object
->pointer
, object
->size
);
1142 kasan_enable_current();
1144 return object
->checksum
!= old_csum
;
1148 * Memory scanning is a long process and it needs to be interruptable. This
1149 * function checks whether such interrupt condition occurred.
1151 static int scan_should_stop(void)
1153 if (!kmemleak_enabled
)
1157 * This function may be called from either process or kthread context,
1158 * hence the need to check for both stop conditions.
1161 return signal_pending(current
);
1163 return kthread_should_stop();
1169 * Scan a memory block (exclusive range) for valid pointers and add those
1170 * found to the gray list.
1172 static void scan_block(void *_start
, void *_end
,
1173 struct kmemleak_object
*scanned
, int allow_resched
)
1176 unsigned long *start
= PTR_ALIGN(_start
, BYTES_PER_POINTER
);
1177 unsigned long *end
= _end
- (BYTES_PER_POINTER
- 1);
1179 for (ptr
= start
; ptr
< end
; ptr
++) {
1180 struct kmemleak_object
*object
;
1181 unsigned long flags
;
1182 unsigned long pointer
;
1186 if (scan_should_stop())
1189 /* don't scan uninitialized memory */
1190 if (!kmemcheck_is_obj_initialized((unsigned long)ptr
,
1194 kasan_disable_current();
1196 kasan_enable_current();
1198 object
= find_and_get_object(pointer
, 1);
1201 if (object
== scanned
) {
1202 /* self referenced, ignore */
1208 * Avoid the lockdep recursive warning on object->lock being
1209 * previously acquired in scan_object(). These locks are
1210 * enclosed by scan_mutex.
1212 spin_lock_irqsave_nested(&object
->lock
, flags
,
1213 SINGLE_DEPTH_NESTING
);
1214 if (!color_white(object
)) {
1215 /* non-orphan, ignored or new */
1216 spin_unlock_irqrestore(&object
->lock
, flags
);
1222 * Increase the object's reference count (number of pointers
1223 * to the memory block). If this count reaches the required
1224 * minimum, the object's color will become gray and it will be
1225 * added to the gray_list.
1228 if (color_gray(object
)) {
1229 list_add_tail(&object
->gray_list
, &gray_list
);
1230 spin_unlock_irqrestore(&object
->lock
, flags
);
1234 spin_unlock_irqrestore(&object
->lock
, flags
);
1240 * Scan a memory block corresponding to a kmemleak_object. A condition is
1241 * that object->use_count >= 1.
1243 static void scan_object(struct kmemleak_object
*object
)
1245 struct kmemleak_scan_area
*area
;
1246 unsigned long flags
;
1249 * Once the object->lock is acquired, the corresponding memory block
1250 * cannot be freed (the same lock is acquired in delete_object).
1252 spin_lock_irqsave(&object
->lock
, flags
);
1253 if (object
->flags
& OBJECT_NO_SCAN
)
1255 if (!(object
->flags
& OBJECT_ALLOCATED
))
1256 /* already freed object */
1258 if (hlist_empty(&object
->area_list
)) {
1259 void *start
= (void *)object
->pointer
;
1260 void *end
= (void *)(object
->pointer
+ object
->size
);
1262 while (start
< end
&& (object
->flags
& OBJECT_ALLOCATED
) &&
1263 !(object
->flags
& OBJECT_NO_SCAN
)) {
1264 scan_block(start
, min(start
+ MAX_SCAN_SIZE
, end
),
1266 start
+= MAX_SCAN_SIZE
;
1268 spin_unlock_irqrestore(&object
->lock
, flags
);
1270 spin_lock_irqsave(&object
->lock
, flags
);
1273 hlist_for_each_entry(area
, &object
->area_list
, node
)
1274 scan_block((void *)area
->start
,
1275 (void *)(area
->start
+ area
->size
),
1278 spin_unlock_irqrestore(&object
->lock
, flags
);
1282 * Scan the objects already referenced (gray objects). More objects will be
1283 * referenced and, if there are no memory leaks, all the objects are scanned.
1285 static void scan_gray_list(void)
1287 struct kmemleak_object
*object
, *tmp
;
1290 * The list traversal is safe for both tail additions and removals
1291 * from inside the loop. The kmemleak objects cannot be freed from
1292 * outside the loop because their use_count was incremented.
1294 object
= list_entry(gray_list
.next
, typeof(*object
), gray_list
);
1295 while (&object
->gray_list
!= &gray_list
) {
1298 /* may add new objects to the list */
1299 if (!scan_should_stop())
1300 scan_object(object
);
1302 tmp
= list_entry(object
->gray_list
.next
, typeof(*object
),
1305 /* remove the object from the list and release it */
1306 list_del(&object
->gray_list
);
1311 WARN_ON(!list_empty(&gray_list
));
1315 * Scan data sections and all the referenced memory blocks allocated via the
1316 * kernel's standard allocators. This function must be called with the
1319 static void kmemleak_scan(void)
1321 unsigned long flags
;
1322 struct kmemleak_object
*object
;
1326 jiffies_last_scan
= jiffies
;
1328 /* prepare the kmemleak_object's */
1330 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1331 spin_lock_irqsave(&object
->lock
, flags
);
1334 * With a few exceptions there should be a maximum of
1335 * 1 reference to any object at this point.
1337 if (atomic_read(&object
->use_count
) > 1) {
1338 pr_debug("object->use_count = %d\n",
1339 atomic_read(&object
->use_count
));
1340 dump_object_info(object
);
1343 /* reset the reference count (whiten the object) */
1345 if (color_gray(object
) && get_object(object
))
1346 list_add_tail(&object
->gray_list
, &gray_list
);
1348 spin_unlock_irqrestore(&object
->lock
, flags
);
1352 /* data/bss scanning */
1353 scan_block(_sdata
, _edata
, NULL
, 1);
1354 scan_block(__bss_start
, __bss_stop
, NULL
, 1);
1357 /* per-cpu sections scanning */
1358 for_each_possible_cpu(i
)
1359 scan_block(__per_cpu_start
+ per_cpu_offset(i
),
1360 __per_cpu_end
+ per_cpu_offset(i
), NULL
, 1);
1364 * Struct page scanning for each node.
1367 for_each_online_node(i
) {
1368 unsigned long start_pfn
= node_start_pfn(i
);
1369 unsigned long end_pfn
= node_end_pfn(i
);
1372 for (pfn
= start_pfn
; pfn
< end_pfn
; pfn
++) {
1375 if (!pfn_valid(pfn
))
1377 page
= pfn_to_page(pfn
);
1378 /* only scan if page is in use */
1379 if (page_count(page
) == 0)
1381 scan_block(page
, page
+ 1, NULL
, 1);
1387 * Scanning the task stacks (may introduce false negatives).
1389 if (kmemleak_stack_scan
) {
1390 struct task_struct
*p
, *g
;
1392 read_lock(&tasklist_lock
);
1393 do_each_thread(g
, p
) {
1394 scan_block(task_stack_page(p
), task_stack_page(p
) +
1395 THREAD_SIZE
, NULL
, 0);
1396 } while_each_thread(g
, p
);
1397 read_unlock(&tasklist_lock
);
1401 * Scan the objects already referenced from the sections scanned
1407 * Check for new or unreferenced objects modified since the previous
1408 * scan and color them gray until the next scan.
1411 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1412 spin_lock_irqsave(&object
->lock
, flags
);
1413 if (color_white(object
) && (object
->flags
& OBJECT_ALLOCATED
)
1414 && update_checksum(object
) && get_object(object
)) {
1415 /* color it gray temporarily */
1416 object
->count
= object
->min_count
;
1417 list_add_tail(&object
->gray_list
, &gray_list
);
1419 spin_unlock_irqrestore(&object
->lock
, flags
);
1424 * Re-scan the gray list for modified unreferenced objects.
1429 * If scanning was stopped do not report any new unreferenced objects.
1431 if (scan_should_stop())
1435 * Scanning result reporting.
1438 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1439 spin_lock_irqsave(&object
->lock
, flags
);
1440 if (unreferenced_object(object
) &&
1441 !(object
->flags
& OBJECT_REPORTED
)) {
1442 object
->flags
|= OBJECT_REPORTED
;
1445 spin_unlock_irqrestore(&object
->lock
, flags
);
1450 kmemleak_found_leaks
= true;
1452 pr_info("%d new suspected memory leaks (see "
1453 "/sys/kernel/debug/kmemleak)\n", new_leaks
);
1459 * Thread function performing automatic memory scanning. Unreferenced objects
1460 * at the end of a memory scan are reported but only the first time.
1462 static int kmemleak_scan_thread(void *arg
)
1464 static int first_run
= 1;
1466 pr_info("Automatic memory scanning thread started\n");
1467 set_user_nice(current
, 10);
1470 * Wait before the first scan to allow the system to fully initialize.
1474 ssleep(SECS_FIRST_SCAN
);
1477 while (!kthread_should_stop()) {
1478 signed long timeout
= jiffies_scan_wait
;
1480 mutex_lock(&scan_mutex
);
1482 mutex_unlock(&scan_mutex
);
1484 /* wait before the next scan */
1485 while (timeout
&& !kthread_should_stop())
1486 timeout
= schedule_timeout_interruptible(timeout
);
1489 pr_info("Automatic memory scanning thread ended\n");
1495 * Start the automatic memory scanning thread. This function must be called
1496 * with the scan_mutex held.
1498 static void start_scan_thread(void)
1502 scan_thread
= kthread_run(kmemleak_scan_thread
, NULL
, "kmemleak");
1503 if (IS_ERR(scan_thread
)) {
1504 pr_warning("Failed to create the scan thread\n");
1510 * Stop the automatic memory scanning thread. This function must be called
1511 * with the scan_mutex held.
1513 static void stop_scan_thread(void)
1516 kthread_stop(scan_thread
);
1522 * Iterate over the object_list and return the first valid object at or after
1523 * the required position with its use_count incremented. The function triggers
1524 * a memory scanning when the pos argument points to the first position.
1526 static void *kmemleak_seq_start(struct seq_file
*seq
, loff_t
*pos
)
1528 struct kmemleak_object
*object
;
1532 err
= mutex_lock_interruptible(&scan_mutex
);
1534 return ERR_PTR(err
);
1537 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1540 if (get_object(object
))
1549 * Return the next object in the object_list. The function decrements the
1550 * use_count of the previous object and increases that of the next one.
1552 static void *kmemleak_seq_next(struct seq_file
*seq
, void *v
, loff_t
*pos
)
1554 struct kmemleak_object
*prev_obj
= v
;
1555 struct kmemleak_object
*next_obj
= NULL
;
1556 struct kmemleak_object
*obj
= prev_obj
;
1560 list_for_each_entry_continue_rcu(obj
, &object_list
, object_list
) {
1561 if (get_object(obj
)) {
1567 put_object(prev_obj
);
1572 * Decrement the use_count of the last object required, if any.
1574 static void kmemleak_seq_stop(struct seq_file
*seq
, void *v
)
1578 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1579 * waiting was interrupted, so only release it if !IS_ERR.
1582 mutex_unlock(&scan_mutex
);
1589 * Print the information for an unreferenced object to the seq file.
1591 static int kmemleak_seq_show(struct seq_file
*seq
, void *v
)
1593 struct kmemleak_object
*object
= v
;
1594 unsigned long flags
;
1596 spin_lock_irqsave(&object
->lock
, flags
);
1597 if ((object
->flags
& OBJECT_REPORTED
) && unreferenced_object(object
))
1598 print_unreferenced(seq
, object
);
1599 spin_unlock_irqrestore(&object
->lock
, flags
);
1603 static const struct seq_operations kmemleak_seq_ops
= {
1604 .start
= kmemleak_seq_start
,
1605 .next
= kmemleak_seq_next
,
1606 .stop
= kmemleak_seq_stop
,
1607 .show
= kmemleak_seq_show
,
1610 static int kmemleak_open(struct inode
*inode
, struct file
*file
)
1612 return seq_open(file
, &kmemleak_seq_ops
);
1615 static int dump_str_object_info(const char *str
)
1617 unsigned long flags
;
1618 struct kmemleak_object
*object
;
1621 if (kstrtoul(str
, 0, &addr
))
1623 object
= find_and_get_object(addr
, 0);
1625 pr_info("Unknown object at 0x%08lx\n", addr
);
1629 spin_lock_irqsave(&object
->lock
, flags
);
1630 dump_object_info(object
);
1631 spin_unlock_irqrestore(&object
->lock
, flags
);
1638 * We use grey instead of black to ensure we can do future scans on the same
1639 * objects. If we did not do future scans these black objects could
1640 * potentially contain references to newly allocated objects in the future and
1641 * we'd end up with false positives.
1643 static void kmemleak_clear(void)
1645 struct kmemleak_object
*object
;
1646 unsigned long flags
;
1649 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1650 spin_lock_irqsave(&object
->lock
, flags
);
1651 if ((object
->flags
& OBJECT_REPORTED
) &&
1652 unreferenced_object(object
))
1653 __paint_it(object
, KMEMLEAK_GREY
);
1654 spin_unlock_irqrestore(&object
->lock
, flags
);
1658 kmemleak_found_leaks
= false;
1661 static void __kmemleak_do_cleanup(void);
1664 * File write operation to configure kmemleak at run-time. The following
1665 * commands can be written to the /sys/kernel/debug/kmemleak file:
1666 * off - disable kmemleak (irreversible)
1667 * stack=on - enable the task stacks scanning
1668 * stack=off - disable the tasks stacks scanning
1669 * scan=on - start the automatic memory scanning thread
1670 * scan=off - stop the automatic memory scanning thread
1671 * scan=... - set the automatic memory scanning period in seconds (0 to
1673 * scan - trigger a memory scan
1674 * clear - mark all current reported unreferenced kmemleak objects as
1675 * grey to ignore printing them, or free all kmemleak objects
1676 * if kmemleak has been disabled.
1677 * dump=... - dump information about the object found at the given address
1679 static ssize_t
kmemleak_write(struct file
*file
, const char __user
*user_buf
,
1680 size_t size
, loff_t
*ppos
)
1686 buf_size
= min(size
, (sizeof(buf
) - 1));
1687 if (strncpy_from_user(buf
, user_buf
, buf_size
) < 0)
1691 ret
= mutex_lock_interruptible(&scan_mutex
);
1695 if (strncmp(buf
, "clear", 5) == 0) {
1696 if (kmemleak_enabled
)
1699 __kmemleak_do_cleanup();
1703 if (!kmemleak_enabled
) {
1708 if (strncmp(buf
, "off", 3) == 0)
1710 else if (strncmp(buf
, "stack=on", 8) == 0)
1711 kmemleak_stack_scan
= 1;
1712 else if (strncmp(buf
, "stack=off", 9) == 0)
1713 kmemleak_stack_scan
= 0;
1714 else if (strncmp(buf
, "scan=on", 7) == 0)
1715 start_scan_thread();
1716 else if (strncmp(buf
, "scan=off", 8) == 0)
1718 else if (strncmp(buf
, "scan=", 5) == 0) {
1721 ret
= kstrtoul(buf
+ 5, 0, &secs
);
1726 jiffies_scan_wait
= msecs_to_jiffies(secs
* 1000);
1727 start_scan_thread();
1729 } else if (strncmp(buf
, "scan", 4) == 0)
1731 else if (strncmp(buf
, "dump=", 5) == 0)
1732 ret
= dump_str_object_info(buf
+ 5);
1737 mutex_unlock(&scan_mutex
);
1741 /* ignore the rest of the buffer, only one command at a time */
1746 static const struct file_operations kmemleak_fops
= {
1747 .owner
= THIS_MODULE
,
1748 .open
= kmemleak_open
,
1750 .write
= kmemleak_write
,
1751 .llseek
= seq_lseek
,
1752 .release
= seq_release
,
1755 static void __kmemleak_do_cleanup(void)
1757 struct kmemleak_object
*object
;
1760 list_for_each_entry_rcu(object
, &object_list
, object_list
)
1761 delete_object_full(object
->pointer
);
1766 * Stop the memory scanning thread and free the kmemleak internal objects if
1767 * no previous scan thread (otherwise, kmemleak may still have some useful
1768 * information on memory leaks).
1770 static void kmemleak_do_cleanup(struct work_struct
*work
)
1775 * Once the scan thread has stopped, it is safe to no longer track
1776 * object freeing. Ordering of the scan thread stopping and the memory
1777 * accesses below is guaranteed by the kthread_stop() function.
1779 kmemleak_free_enabled
= 0;
1781 if (!kmemleak_found_leaks
)
1782 __kmemleak_do_cleanup();
1784 pr_info("Kmemleak disabled without freeing internal data. "
1785 "Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\"\n");
1788 static DECLARE_WORK(cleanup_work
, kmemleak_do_cleanup
);
1791 * Disable kmemleak. No memory allocation/freeing will be traced once this
1792 * function is called. Disabling kmemleak is an irreversible operation.
1794 static void kmemleak_disable(void)
1796 /* atomically check whether it was already invoked */
1797 if (cmpxchg(&kmemleak_error
, 0, 1))
1800 /* stop any memory operation tracing */
1801 kmemleak_enabled
= 0;
1803 /* check whether it is too early for a kernel thread */
1804 if (kmemleak_initialized
)
1805 schedule_work(&cleanup_work
);
1807 kmemleak_free_enabled
= 0;
1809 pr_info("Kernel memory leak detector disabled\n");
1813 * Allow boot-time kmemleak disabling (enabled by default).
1815 static int kmemleak_boot_config(char *str
)
1819 if (strcmp(str
, "off") == 0)
1821 else if (strcmp(str
, "on") == 0)
1822 kmemleak_skip_disable
= 1;
1827 early_param("kmemleak", kmemleak_boot_config
);
1829 static void __init
print_log_trace(struct early_log
*log
)
1831 struct stack_trace trace
;
1833 trace
.nr_entries
= log
->trace_len
;
1834 trace
.entries
= log
->trace
;
1836 pr_notice("Early log backtrace:\n");
1837 print_stack_trace(&trace
, 2);
1841 * Kmemleak initialization.
1843 void __init
kmemleak_init(void)
1846 unsigned long flags
;
1848 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1849 if (!kmemleak_skip_disable
) {
1850 kmemleak_early_log
= 0;
1856 jiffies_min_age
= msecs_to_jiffies(MSECS_MIN_AGE
);
1857 jiffies_scan_wait
= msecs_to_jiffies(SECS_SCAN_WAIT
* 1000);
1859 object_cache
= KMEM_CACHE(kmemleak_object
, SLAB_NOLEAKTRACE
);
1860 scan_area_cache
= KMEM_CACHE(kmemleak_scan_area
, SLAB_NOLEAKTRACE
);
1862 if (crt_early_log
>= ARRAY_SIZE(early_log
))
1863 pr_warning("Early log buffer exceeded (%d), please increase "
1864 "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log
);
1866 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1867 local_irq_save(flags
);
1868 kmemleak_early_log
= 0;
1869 if (kmemleak_error
) {
1870 local_irq_restore(flags
);
1873 kmemleak_enabled
= 1;
1874 kmemleak_free_enabled
= 1;
1876 local_irq_restore(flags
);
1879 * This is the point where tracking allocations is safe. Automatic
1880 * scanning is started during the late initcall. Add the early logged
1881 * callbacks to the kmemleak infrastructure.
1883 for (i
= 0; i
< crt_early_log
; i
++) {
1884 struct early_log
*log
= &early_log
[i
];
1886 switch (log
->op_type
) {
1887 case KMEMLEAK_ALLOC
:
1890 case KMEMLEAK_ALLOC_PERCPU
:
1891 early_alloc_percpu(log
);
1894 kmemleak_free(log
->ptr
);
1896 case KMEMLEAK_FREE_PART
:
1897 kmemleak_free_part(log
->ptr
, log
->size
);
1899 case KMEMLEAK_FREE_PERCPU
:
1900 kmemleak_free_percpu(log
->ptr
);
1902 case KMEMLEAK_NOT_LEAK
:
1903 kmemleak_not_leak(log
->ptr
);
1905 case KMEMLEAK_IGNORE
:
1906 kmemleak_ignore(log
->ptr
);
1908 case KMEMLEAK_SCAN_AREA
:
1909 kmemleak_scan_area(log
->ptr
, log
->size
, GFP_KERNEL
);
1911 case KMEMLEAK_NO_SCAN
:
1912 kmemleak_no_scan(log
->ptr
);
1915 kmemleak_warn("Unknown early log operation: %d\n",
1919 if (kmemleak_warning
) {
1920 print_log_trace(log
);
1921 kmemleak_warning
= 0;
1927 * Late initialization function.
1929 static int __init
kmemleak_late_init(void)
1931 struct dentry
*dentry
;
1933 kmemleak_initialized
= 1;
1935 if (kmemleak_error
) {
1937 * Some error occurred and kmemleak was disabled. There is a
1938 * small chance that kmemleak_disable() was called immediately
1939 * after setting kmemleak_initialized and we may end up with
1940 * two clean-up threads but serialized by scan_mutex.
1942 schedule_work(&cleanup_work
);
1946 dentry
= debugfs_create_file("kmemleak", S_IRUGO
, NULL
, NULL
,
1949 pr_warning("Failed to create the debugfs kmemleak file\n");
1950 mutex_lock(&scan_mutex
);
1951 start_scan_thread();
1952 mutex_unlock(&scan_mutex
);
1954 pr_info("Kernel memory leak detector initialized\n");
1958 late_initcall(kmemleak_late_init
);