1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 2008 ARM Limited
6 * Written by Catalin Marinas <catalin.marinas@arm.com>
8 * For more information on the algorithm and kmemleak usage, please see
9 * Documentation/dev-tools/kmemleak.rst.
14 * The following locks and mutexes are used by kmemleak:
16 * - kmemleak_lock (raw_spinlock_t): protects the object_list modifications and
17 * accesses to the object_tree_root. The object_list is the main list
18 * holding the metadata (struct kmemleak_object) for the allocated memory
19 * blocks. The object_tree_root is a red black tree used to look-up
20 * metadata based on a pointer to the corresponding memory block. The
21 * kmemleak_object structures are added to the object_list and
22 * object_tree_root in the create_object() function called from the
23 * kmemleak_alloc() callback and removed in delete_object() called from the
24 * kmemleak_free() callback
25 * - kmemleak_object.lock (raw_spinlock_t): protects a kmemleak_object.
26 * Accesses to the metadata (e.g. count) are protected by this lock. Note
27 * that some members of this structure may be protected by other means
28 * (atomic or kmemleak_lock). This lock is also held when scanning the
29 * corresponding memory block to avoid the kernel freeing it via the
30 * kmemleak_free() callback. This is less heavyweight than holding a global
31 * lock like kmemleak_lock during scanning.
32 * - scan_mutex (mutex): ensures that only one thread may scan the memory for
33 * unreferenced objects at a time. The gray_list contains the objects which
34 * are already referenced or marked as false positives and need to be
35 * scanned. This list is only modified during a scanning episode when the
36 * scan_mutex is held. At the end of a scan, the gray_list is always empty.
37 * Note that the kmemleak_object.use_count is incremented when an object is
38 * added to the gray_list and therefore cannot be freed. This mutex also
39 * prevents multiple users of the "kmemleak" debugfs file together with
40 * modifications to the memory scanning parameters including the scan_thread
43 * Locks and mutexes are acquired/nested in the following order:
45 * scan_mutex [-> object->lock] -> kmemleak_lock -> other_object->lock (SINGLE_DEPTH_NESTING)
47 * No kmemleak_lock and object->lock nesting is allowed outside scan_mutex
50 * The kmemleak_object structures have a use_count incremented or decremented
51 * using the get_object()/put_object() functions. When the use_count becomes
52 * 0, this count can no longer be incremented and put_object() schedules the
53 * kmemleak_object freeing via an RCU callback. All calls to the get_object()
54 * function must be protected by rcu_read_lock() to avoid accessing a freed
58 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
60 #include <linux/init.h>
61 #include <linux/kernel.h>
62 #include <linux/list.h>
63 #include <linux/sched/signal.h>
64 #include <linux/sched/task.h>
65 #include <linux/sched/task_stack.h>
66 #include <linux/jiffies.h>
67 #include <linux/delay.h>
68 #include <linux/export.h>
69 #include <linux/kthread.h>
70 #include <linux/rbtree.h>
72 #include <linux/debugfs.h>
73 #include <linux/seq_file.h>
74 #include <linux/cpumask.h>
75 #include <linux/spinlock.h>
76 #include <linux/module.h>
77 #include <linux/mutex.h>
78 #include <linux/rcupdate.h>
79 #include <linux/stacktrace.h>
80 #include <linux/cache.h>
81 #include <linux/percpu.h>
82 #include <linux/memblock.h>
83 #include <linux/pfn.h>
84 #include <linux/mmzone.h>
85 #include <linux/slab.h>
86 #include <linux/thread_info.h>
87 #include <linux/err.h>
88 #include <linux/uaccess.h>
89 #include <linux/string.h>
90 #include <linux/nodemask.h>
92 #include <linux/workqueue.h>
93 #include <linux/crc32.h>
95 #include <asm/sections.h>
96 #include <asm/processor.h>
97 #include <linux/atomic.h>
99 #include <linux/kasan.h>
100 #include <linux/kfence.h>
101 #include <linux/kmemleak.h>
102 #include <linux/memory_hotplug.h>
105 * Kmemleak configuration and common defines.
107 #define MAX_TRACE 16 /* stack trace length */
108 #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
109 #define SECS_FIRST_SCAN 60 /* delay before the first scan */
110 #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
111 #define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
113 #define BYTES_PER_POINTER sizeof(void *)
115 /* GFP bitmask for kmemleak internal allocations */
116 #define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
117 __GFP_NORETRY | __GFP_NOMEMALLOC | \
120 /* scanning area inside a memory block */
121 struct kmemleak_scan_area
{
122 struct hlist_node node
;
127 #define KMEMLEAK_GREY 0
128 #define KMEMLEAK_BLACK -1
131 * Structure holding the metadata for each allocated memory block.
132 * Modifications to such objects should be made while holding the
133 * object->lock. Insertions or deletions from object_list, gray_list or
134 * rb_node are already protected by the corresponding locks or mutex (see
135 * the notes on locking above). These objects are reference-counted
136 * (use_count) and freed using the RCU mechanism.
138 struct kmemleak_object
{
140 unsigned int flags
; /* object status flags */
141 struct list_head object_list
;
142 struct list_head gray_list
;
143 struct rb_node rb_node
;
144 struct rcu_head rcu
; /* object_list lockless traversal */
145 /* object usage count; object freed when use_count == 0 */
147 unsigned long pointer
;
149 /* pass surplus references to this pointer */
150 unsigned long excess_ref
;
151 /* minimum number of a pointers found before it is considered leak */
153 /* the total number of pointers found pointing to this object */
155 /* checksum for detecting modified objects */
157 /* memory ranges to be scanned inside an object (empty for all) */
158 struct hlist_head area_list
;
159 unsigned long trace
[MAX_TRACE
];
160 unsigned int trace_len
;
161 unsigned long jiffies
; /* creation timestamp */
162 pid_t pid
; /* pid of the current task */
163 char comm
[TASK_COMM_LEN
]; /* executable name */
166 /* flag representing the memory block allocation status */
167 #define OBJECT_ALLOCATED (1 << 0)
168 /* flag set after the first reporting of an unreference object */
169 #define OBJECT_REPORTED (1 << 1)
170 /* flag set to not scan the object */
171 #define OBJECT_NO_SCAN (1 << 2)
172 /* flag set to fully scan the object when scan_area allocation failed */
173 #define OBJECT_FULL_SCAN (1 << 3)
175 #define HEX_PREFIX " "
176 /* number of bytes to print per line; must be 16 or 32 */
177 #define HEX_ROW_SIZE 16
178 /* number of bytes to print at a time (1, 2, 4, 8) */
179 #define HEX_GROUP_SIZE 1
180 /* include ASCII after the hex output */
182 /* max number of lines to be printed */
183 #define HEX_MAX_LINES 2
185 /* the list of all allocated objects */
186 static LIST_HEAD(object_list
);
187 /* the list of gray-colored objects (see color_gray comment below) */
188 static LIST_HEAD(gray_list
);
189 /* memory pool allocation */
190 static struct kmemleak_object mem_pool
[CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE
];
191 static int mem_pool_free_count
= ARRAY_SIZE(mem_pool
);
192 static LIST_HEAD(mem_pool_free_list
);
193 /* search tree for object boundaries */
194 static struct rb_root object_tree_root
= RB_ROOT
;
195 /* protecting the access to object_list and object_tree_root */
196 static DEFINE_RAW_SPINLOCK(kmemleak_lock
);
198 /* allocation caches for kmemleak internal data */
199 static struct kmem_cache
*object_cache
;
200 static struct kmem_cache
*scan_area_cache
;
202 /* set if tracing memory operations is enabled */
203 static int kmemleak_enabled
= 1;
204 /* same as above but only for the kmemleak_free() callback */
205 static int kmemleak_free_enabled
= 1;
206 /* set in the late_initcall if there were no errors */
207 static int kmemleak_initialized
;
208 /* set if a kmemleak warning was issued */
209 static int kmemleak_warning
;
210 /* set if a fatal kmemleak error has occurred */
211 static int kmemleak_error
;
213 /* minimum and maximum address that may be valid pointers */
214 static unsigned long min_addr
= ULONG_MAX
;
215 static unsigned long max_addr
;
217 static struct task_struct
*scan_thread
;
218 /* used to avoid reporting of recently allocated objects */
219 static unsigned long jiffies_min_age
;
220 static unsigned long jiffies_last_scan
;
221 /* delay between automatic memory scannings */
222 static signed long jiffies_scan_wait
;
223 /* enables or disables the task stacks scanning */
224 static int kmemleak_stack_scan
= 1;
225 /* protects the memory scanning, parameters and debug/kmemleak file access */
226 static DEFINE_MUTEX(scan_mutex
);
227 /* setting kmemleak=on, will set this var, skipping the disable */
228 static int kmemleak_skip_disable
;
229 /* If there are leaks that can be reported */
230 static bool kmemleak_found_leaks
;
232 static bool kmemleak_verbose
;
233 module_param_named(verbose
, kmemleak_verbose
, bool, 0600);
235 static void kmemleak_disable(void);
238 * Print a warning and dump the stack trace.
240 #define kmemleak_warn(x...) do { \
243 kmemleak_warning = 1; \
247 * Macro invoked when a serious kmemleak condition occurred and cannot be
248 * recovered from. Kmemleak will be disabled and further allocation/freeing
249 * tracing no longer available.
251 #define kmemleak_stop(x...) do { \
253 kmemleak_disable(); \
256 #define warn_or_seq_printf(seq, fmt, ...) do { \
258 seq_printf(seq, fmt, ##__VA_ARGS__); \
260 pr_warn(fmt, ##__VA_ARGS__); \
263 static void warn_or_seq_hex_dump(struct seq_file
*seq
, int prefix_type
,
264 int rowsize
, int groupsize
, const void *buf
,
265 size_t len
, bool ascii
)
268 seq_hex_dump(seq
, HEX_PREFIX
, prefix_type
, rowsize
, groupsize
,
271 print_hex_dump(KERN_WARNING
, pr_fmt(HEX_PREFIX
), prefix_type
,
272 rowsize
, groupsize
, buf
, len
, ascii
);
276 * Printing of the objects hex dump to the seq file. The number of lines to be
277 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
278 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
279 * with the object->lock held.
281 static void hex_dump_object(struct seq_file
*seq
,
282 struct kmemleak_object
*object
)
284 const u8
*ptr
= (const u8
*)object
->pointer
;
287 /* limit the number of lines to HEX_MAX_LINES */
288 len
= min_t(size_t, object
->size
, HEX_MAX_LINES
* HEX_ROW_SIZE
);
290 warn_or_seq_printf(seq
, " hex dump (first %zu bytes):\n", len
);
291 kasan_disable_current();
292 warn_or_seq_hex_dump(seq
, DUMP_PREFIX_NONE
, HEX_ROW_SIZE
,
293 HEX_GROUP_SIZE
, ptr
, len
, HEX_ASCII
);
294 kasan_enable_current();
298 * Object colors, encoded with count and min_count:
299 * - white - orphan object, not enough references to it (count < min_count)
300 * - gray - not orphan, not marked as false positive (min_count == 0) or
301 * sufficient references to it (count >= min_count)
302 * - black - ignore, it doesn't contain references (e.g. text section)
303 * (min_count == -1). No function defined for this color.
304 * Newly created objects don't have any color assigned (object->count == -1)
305 * before the next memory scan when they become white.
307 static bool color_white(const struct kmemleak_object
*object
)
309 return object
->count
!= KMEMLEAK_BLACK
&&
310 object
->count
< object
->min_count
;
313 static bool color_gray(const struct kmemleak_object
*object
)
315 return object
->min_count
!= KMEMLEAK_BLACK
&&
316 object
->count
>= object
->min_count
;
320 * Objects are considered unreferenced only if their color is white, they have
321 * not be deleted and have a minimum age to avoid false positives caused by
322 * pointers temporarily stored in CPU registers.
324 static bool unreferenced_object(struct kmemleak_object
*object
)
326 return (color_white(object
) && object
->flags
& OBJECT_ALLOCATED
) &&
327 time_before_eq(object
->jiffies
+ jiffies_min_age
,
332 * Printing of the unreferenced objects information to the seq file. The
333 * print_unreferenced function must be called with the object->lock held.
335 static void print_unreferenced(struct seq_file
*seq
,
336 struct kmemleak_object
*object
)
339 unsigned int msecs_age
= jiffies_to_msecs(jiffies
- object
->jiffies
);
341 warn_or_seq_printf(seq
, "unreferenced object 0x%08lx (size %zu):\n",
342 object
->pointer
, object
->size
);
343 warn_or_seq_printf(seq
, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
344 object
->comm
, object
->pid
, object
->jiffies
,
345 msecs_age
/ 1000, msecs_age
% 1000);
346 hex_dump_object(seq
, object
);
347 warn_or_seq_printf(seq
, " backtrace:\n");
349 for (i
= 0; i
< object
->trace_len
; i
++) {
350 void *ptr
= (void *)object
->trace
[i
];
351 warn_or_seq_printf(seq
, " [<%p>] %pS\n", ptr
, ptr
);
356 * Print the kmemleak_object information. This function is used mainly for
357 * debugging special cases when kmemleak operations. It must be called with
358 * the object->lock held.
360 static void dump_object_info(struct kmemleak_object
*object
)
362 pr_notice("Object 0x%08lx (size %zu):\n",
363 object
->pointer
, object
->size
);
364 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
365 object
->comm
, object
->pid
, object
->jiffies
);
366 pr_notice(" min_count = %d\n", object
->min_count
);
367 pr_notice(" count = %d\n", object
->count
);
368 pr_notice(" flags = 0x%x\n", object
->flags
);
369 pr_notice(" checksum = %u\n", object
->checksum
);
370 pr_notice(" backtrace:\n");
371 stack_trace_print(object
->trace
, object
->trace_len
, 4);
375 * Look-up a memory block metadata (kmemleak_object) in the object search
376 * tree based on a pointer value. If alias is 0, only values pointing to the
377 * beginning of the memory block are allowed. The kmemleak_lock must be held
378 * when calling this function.
380 static struct kmemleak_object
*lookup_object(unsigned long ptr
, int alias
)
382 struct rb_node
*rb
= object_tree_root
.rb_node
;
385 struct kmemleak_object
*object
=
386 rb_entry(rb
, struct kmemleak_object
, rb_node
);
387 if (ptr
< object
->pointer
)
388 rb
= object
->rb_node
.rb_left
;
389 else if (object
->pointer
+ object
->size
<= ptr
)
390 rb
= object
->rb_node
.rb_right
;
391 else if (object
->pointer
== ptr
|| alias
)
394 kmemleak_warn("Found object by alias at 0x%08lx\n",
396 dump_object_info(object
);
404 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
405 * that once an object's use_count reached 0, the RCU freeing was already
406 * registered and the object should no longer be used. This function must be
407 * called under the protection of rcu_read_lock().
409 static int get_object(struct kmemleak_object
*object
)
411 return atomic_inc_not_zero(&object
->use_count
);
415 * Memory pool allocation and freeing. kmemleak_lock must not be held.
417 static struct kmemleak_object
*mem_pool_alloc(gfp_t gfp
)
420 struct kmemleak_object
*object
;
422 /* try the slab allocator first */
424 object
= kmem_cache_alloc(object_cache
, gfp_kmemleak_mask(gfp
));
429 /* slab allocation failed, try the memory pool */
430 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
431 object
= list_first_entry_or_null(&mem_pool_free_list
,
432 typeof(*object
), object_list
);
434 list_del(&object
->object_list
);
435 else if (mem_pool_free_count
)
436 object
= &mem_pool
[--mem_pool_free_count
];
438 pr_warn_once("Memory pool empty, consider increasing CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE\n");
439 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
445 * Return the object to either the slab allocator or the memory pool.
447 static void mem_pool_free(struct kmemleak_object
*object
)
451 if (object
< mem_pool
|| object
>= mem_pool
+ ARRAY_SIZE(mem_pool
)) {
452 kmem_cache_free(object_cache
, object
);
456 /* add the object to the memory pool free list */
457 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
458 list_add(&object
->object_list
, &mem_pool_free_list
);
459 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
463 * RCU callback to free a kmemleak_object.
465 static void free_object_rcu(struct rcu_head
*rcu
)
467 struct hlist_node
*tmp
;
468 struct kmemleak_scan_area
*area
;
469 struct kmemleak_object
*object
=
470 container_of(rcu
, struct kmemleak_object
, rcu
);
473 * Once use_count is 0 (guaranteed by put_object), there is no other
474 * code accessing this object, hence no need for locking.
476 hlist_for_each_entry_safe(area
, tmp
, &object
->area_list
, node
) {
477 hlist_del(&area
->node
);
478 kmem_cache_free(scan_area_cache
, area
);
480 mem_pool_free(object
);
484 * Decrement the object use_count. Once the count is 0, free the object using
485 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
486 * delete_object() path, the delayed RCU freeing ensures that there is no
487 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
490 static void put_object(struct kmemleak_object
*object
)
492 if (!atomic_dec_and_test(&object
->use_count
))
495 /* should only get here after delete_object was called */
496 WARN_ON(object
->flags
& OBJECT_ALLOCATED
);
499 * It may be too early for the RCU callbacks, however, there is no
500 * concurrent object_list traversal when !object_cache and all objects
501 * came from the memory pool. Free the object directly.
504 call_rcu(&object
->rcu
, free_object_rcu
);
506 free_object_rcu(&object
->rcu
);
510 * Look up an object in the object search tree and increase its use_count.
512 static struct kmemleak_object
*find_and_get_object(unsigned long ptr
, int alias
)
515 struct kmemleak_object
*object
;
518 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
519 object
= lookup_object(ptr
, alias
);
520 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
522 /* check whether the object is still available */
523 if (object
&& !get_object(object
))
531 * Remove an object from the object_tree_root and object_list. Must be called
532 * with the kmemleak_lock held _if_ kmemleak is still enabled.
534 static void __remove_object(struct kmemleak_object
*object
)
536 rb_erase(&object
->rb_node
, &object_tree_root
);
537 list_del_rcu(&object
->object_list
);
541 * Look up an object in the object search tree and remove it from both
542 * object_tree_root and object_list. The returned object's use_count should be
543 * at least 1, as initially set by create_object().
545 static struct kmemleak_object
*find_and_remove_object(unsigned long ptr
, int alias
)
548 struct kmemleak_object
*object
;
550 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
551 object
= lookup_object(ptr
, alias
);
553 __remove_object(object
);
554 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
560 * Save stack trace to the given array of MAX_TRACE size.
562 static int __save_stack_trace(unsigned long *trace
)
564 return stack_trace_save(trace
, MAX_TRACE
, 2);
568 * Create the metadata (struct kmemleak_object) corresponding to an allocated
569 * memory block and add it to the object_list and object_tree_root.
571 static struct kmemleak_object
*create_object(unsigned long ptr
, size_t size
,
572 int min_count
, gfp_t gfp
)
575 struct kmemleak_object
*object
, *parent
;
576 struct rb_node
**link
, *rb_parent
;
577 unsigned long untagged_ptr
;
579 object
= mem_pool_alloc(gfp
);
581 pr_warn("Cannot allocate a kmemleak_object structure\n");
586 INIT_LIST_HEAD(&object
->object_list
);
587 INIT_LIST_HEAD(&object
->gray_list
);
588 INIT_HLIST_HEAD(&object
->area_list
);
589 raw_spin_lock_init(&object
->lock
);
590 atomic_set(&object
->use_count
, 1);
591 object
->flags
= OBJECT_ALLOCATED
;
592 object
->pointer
= ptr
;
593 object
->size
= kfence_ksize((void *)ptr
) ?: size
;
594 object
->excess_ref
= 0;
595 object
->min_count
= min_count
;
596 object
->count
= 0; /* white color initially */
597 object
->jiffies
= jiffies
;
598 object
->checksum
= 0;
600 /* task information */
603 strncpy(object
->comm
, "hardirq", sizeof(object
->comm
));
604 } else if (in_serving_softirq()) {
606 strncpy(object
->comm
, "softirq", sizeof(object
->comm
));
608 object
->pid
= current
->pid
;
610 * There is a small chance of a race with set_task_comm(),
611 * however using get_task_comm() here may cause locking
612 * dependency issues with current->alloc_lock. In the worst
613 * case, the command line is not correct.
615 strncpy(object
->comm
, current
->comm
, sizeof(object
->comm
));
618 /* kernel backtrace */
619 object
->trace_len
= __save_stack_trace(object
->trace
);
621 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
623 untagged_ptr
= (unsigned long)kasan_reset_tag((void *)ptr
);
624 min_addr
= min(min_addr
, untagged_ptr
);
625 max_addr
= max(max_addr
, untagged_ptr
+ size
);
626 link
= &object_tree_root
.rb_node
;
630 parent
= rb_entry(rb_parent
, struct kmemleak_object
, rb_node
);
631 if (ptr
+ size
<= parent
->pointer
)
632 link
= &parent
->rb_node
.rb_left
;
633 else if (parent
->pointer
+ parent
->size
<= ptr
)
634 link
= &parent
->rb_node
.rb_right
;
636 kmemleak_stop("Cannot insert 0x%lx into the object search tree (overlaps existing)\n",
639 * No need for parent->lock here since "parent" cannot
640 * be freed while the kmemleak_lock is held.
642 dump_object_info(parent
);
643 kmem_cache_free(object_cache
, object
);
648 rb_link_node(&object
->rb_node
, rb_parent
, link
);
649 rb_insert_color(&object
->rb_node
, &object_tree_root
);
651 list_add_tail_rcu(&object
->object_list
, &object_list
);
653 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
658 * Mark the object as not allocated and schedule RCU freeing via put_object().
660 static void __delete_object(struct kmemleak_object
*object
)
664 WARN_ON(!(object
->flags
& OBJECT_ALLOCATED
));
665 WARN_ON(atomic_read(&object
->use_count
) < 1);
668 * Locking here also ensures that the corresponding memory block
669 * cannot be freed when it is being scanned.
671 raw_spin_lock_irqsave(&object
->lock
, flags
);
672 object
->flags
&= ~OBJECT_ALLOCATED
;
673 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
678 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
681 static void delete_object_full(unsigned long ptr
)
683 struct kmemleak_object
*object
;
685 object
= find_and_remove_object(ptr
, 0);
688 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
693 __delete_object(object
);
697 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
698 * delete it. If the memory block is partially freed, the function may create
699 * additional metadata for the remaining parts of the block.
701 static void delete_object_part(unsigned long ptr
, size_t size
)
703 struct kmemleak_object
*object
;
704 unsigned long start
, end
;
706 object
= find_and_remove_object(ptr
, 1);
709 kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n",
716 * Create one or two objects that may result from the memory block
717 * split. Note that partial freeing is only done by free_bootmem() and
718 * this happens before kmemleak_init() is called.
720 start
= object
->pointer
;
721 end
= object
->pointer
+ object
->size
;
723 create_object(start
, ptr
- start
, object
->min_count
,
725 if (ptr
+ size
< end
)
726 create_object(ptr
+ size
, end
- ptr
- size
, object
->min_count
,
729 __delete_object(object
);
732 static void __paint_it(struct kmemleak_object
*object
, int color
)
734 object
->min_count
= color
;
735 if (color
== KMEMLEAK_BLACK
)
736 object
->flags
|= OBJECT_NO_SCAN
;
739 static void paint_it(struct kmemleak_object
*object
, int color
)
743 raw_spin_lock_irqsave(&object
->lock
, flags
);
744 __paint_it(object
, color
);
745 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
748 static void paint_ptr(unsigned long ptr
, int color
)
750 struct kmemleak_object
*object
;
752 object
= find_and_get_object(ptr
, 0);
754 kmemleak_warn("Trying to color unknown object at 0x%08lx as %s\n",
756 (color
== KMEMLEAK_GREY
) ? "Grey" :
757 (color
== KMEMLEAK_BLACK
) ? "Black" : "Unknown");
760 paint_it(object
, color
);
765 * Mark an object permanently as gray-colored so that it can no longer be
766 * reported as a leak. This is used in general to mark a false positive.
768 static void make_gray_object(unsigned long ptr
)
770 paint_ptr(ptr
, KMEMLEAK_GREY
);
774 * Mark the object as black-colored so that it is ignored from scans and
777 static void make_black_object(unsigned long ptr
)
779 paint_ptr(ptr
, KMEMLEAK_BLACK
);
783 * Add a scanning area to the object. If at least one such area is added,
784 * kmemleak will only scan these ranges rather than the whole memory block.
786 static void add_scan_area(unsigned long ptr
, size_t size
, gfp_t gfp
)
789 struct kmemleak_object
*object
;
790 struct kmemleak_scan_area
*area
= NULL
;
792 object
= find_and_get_object(ptr
, 1);
794 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
800 area
= kmem_cache_alloc(scan_area_cache
, gfp_kmemleak_mask(gfp
));
802 raw_spin_lock_irqsave(&object
->lock
, flags
);
804 pr_warn_once("Cannot allocate a scan area, scanning the full object\n");
805 /* mark the object for full scan to avoid false positives */
806 object
->flags
|= OBJECT_FULL_SCAN
;
809 if (size
== SIZE_MAX
) {
810 size
= object
->pointer
+ object
->size
- ptr
;
811 } else if (ptr
+ size
> object
->pointer
+ object
->size
) {
812 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr
);
813 dump_object_info(object
);
814 kmem_cache_free(scan_area_cache
, area
);
818 INIT_HLIST_NODE(&area
->node
);
822 hlist_add_head(&area
->node
, &object
->area_list
);
824 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
829 * Any surplus references (object already gray) to 'ptr' are passed to
830 * 'excess_ref'. This is used in the vmalloc() case where a pointer to
831 * vm_struct may be used as an alternative reference to the vmalloc'ed object
832 * (see free_thread_stack()).
834 static void object_set_excess_ref(unsigned long ptr
, unsigned long excess_ref
)
837 struct kmemleak_object
*object
;
839 object
= find_and_get_object(ptr
, 0);
841 kmemleak_warn("Setting excess_ref on unknown object at 0x%08lx\n",
846 raw_spin_lock_irqsave(&object
->lock
, flags
);
847 object
->excess_ref
= excess_ref
;
848 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
853 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
854 * pointer. Such object will not be scanned by kmemleak but references to it
857 static void object_no_scan(unsigned long ptr
)
860 struct kmemleak_object
*object
;
862 object
= find_and_get_object(ptr
, 0);
864 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr
);
868 raw_spin_lock_irqsave(&object
->lock
, flags
);
869 object
->flags
|= OBJECT_NO_SCAN
;
870 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
875 * kmemleak_alloc - register a newly allocated object
876 * @ptr: pointer to beginning of the object
877 * @size: size of the object
878 * @min_count: minimum number of references to this object. If during memory
879 * scanning a number of references less than @min_count is found,
880 * the object is reported as a memory leak. If @min_count is 0,
881 * the object is never reported as a leak. If @min_count is -1,
882 * the object is ignored (not scanned and not reported as a leak)
883 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
885 * This function is called from the kernel allocators when a new object
886 * (memory block) is allocated (kmem_cache_alloc, kmalloc etc.).
888 void __ref
kmemleak_alloc(const void *ptr
, size_t size
, int min_count
,
891 pr_debug("%s(0x%p, %zu, %d)\n", __func__
, ptr
, size
, min_count
);
893 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
894 create_object((unsigned long)ptr
, size
, min_count
, gfp
);
896 EXPORT_SYMBOL_GPL(kmemleak_alloc
);
899 * kmemleak_alloc_percpu - register a newly allocated __percpu object
900 * @ptr: __percpu pointer to beginning of the object
901 * @size: size of the object
902 * @gfp: flags used for kmemleak internal memory allocations
904 * This function is called from the kernel percpu allocator when a new object
905 * (memory block) is allocated (alloc_percpu).
907 void __ref
kmemleak_alloc_percpu(const void __percpu
*ptr
, size_t size
,
912 pr_debug("%s(0x%p, %zu)\n", __func__
, ptr
, size
);
915 * Percpu allocations are only scanned and not reported as leaks
916 * (min_count is set to 0).
918 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
919 for_each_possible_cpu(cpu
)
920 create_object((unsigned long)per_cpu_ptr(ptr
, cpu
),
923 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu
);
926 * kmemleak_vmalloc - register a newly vmalloc'ed object
927 * @area: pointer to vm_struct
928 * @size: size of the object
929 * @gfp: __vmalloc() flags used for kmemleak internal memory allocations
931 * This function is called from the vmalloc() kernel allocator when a new
932 * object (memory block) is allocated.
934 void __ref
kmemleak_vmalloc(const struct vm_struct
*area
, size_t size
, gfp_t gfp
)
936 pr_debug("%s(0x%p, %zu)\n", __func__
, area
, size
);
939 * A min_count = 2 is needed because vm_struct contains a reference to
940 * the virtual address of the vmalloc'ed block.
942 if (kmemleak_enabled
) {
943 create_object((unsigned long)area
->addr
, size
, 2, gfp
);
944 object_set_excess_ref((unsigned long)area
,
945 (unsigned long)area
->addr
);
948 EXPORT_SYMBOL_GPL(kmemleak_vmalloc
);
951 * kmemleak_free - unregister a previously registered object
952 * @ptr: pointer to beginning of the object
954 * This function is called from the kernel allocators when an object (memory
955 * block) is freed (kmem_cache_free, kfree, vfree etc.).
957 void __ref
kmemleak_free(const void *ptr
)
959 pr_debug("%s(0x%p)\n", __func__
, ptr
);
961 if (kmemleak_free_enabled
&& ptr
&& !IS_ERR(ptr
))
962 delete_object_full((unsigned long)ptr
);
964 EXPORT_SYMBOL_GPL(kmemleak_free
);
967 * kmemleak_free_part - partially unregister a previously registered object
968 * @ptr: pointer to the beginning or inside the object. This also
969 * represents the start of the range to be freed
970 * @size: size to be unregistered
972 * This function is called when only a part of a memory block is freed
973 * (usually from the bootmem allocator).
975 void __ref
kmemleak_free_part(const void *ptr
, size_t size
)
977 pr_debug("%s(0x%p)\n", __func__
, ptr
);
979 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
980 delete_object_part((unsigned long)ptr
, size
);
982 EXPORT_SYMBOL_GPL(kmemleak_free_part
);
985 * kmemleak_free_percpu - unregister a previously registered __percpu object
986 * @ptr: __percpu pointer to beginning of the object
988 * This function is called from the kernel percpu allocator when an object
989 * (memory block) is freed (free_percpu).
991 void __ref
kmemleak_free_percpu(const void __percpu
*ptr
)
995 pr_debug("%s(0x%p)\n", __func__
, ptr
);
997 if (kmemleak_free_enabled
&& ptr
&& !IS_ERR(ptr
))
998 for_each_possible_cpu(cpu
)
999 delete_object_full((unsigned long)per_cpu_ptr(ptr
,
1002 EXPORT_SYMBOL_GPL(kmemleak_free_percpu
);
1005 * kmemleak_update_trace - update object allocation stack trace
1006 * @ptr: pointer to beginning of the object
1008 * Override the object allocation stack trace for cases where the actual
1009 * allocation place is not always useful.
1011 void __ref
kmemleak_update_trace(const void *ptr
)
1013 struct kmemleak_object
*object
;
1014 unsigned long flags
;
1016 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1018 if (!kmemleak_enabled
|| IS_ERR_OR_NULL(ptr
))
1021 object
= find_and_get_object((unsigned long)ptr
, 1);
1024 kmemleak_warn("Updating stack trace for unknown object at %p\n",
1030 raw_spin_lock_irqsave(&object
->lock
, flags
);
1031 object
->trace_len
= __save_stack_trace(object
->trace
);
1032 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1036 EXPORT_SYMBOL(kmemleak_update_trace
);
1039 * kmemleak_not_leak - mark an allocated object as false positive
1040 * @ptr: pointer to beginning of the object
1042 * Calling this function on an object will cause the memory block to no longer
1043 * be reported as leak and always be scanned.
1045 void __ref
kmemleak_not_leak(const void *ptr
)
1047 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1049 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1050 make_gray_object((unsigned long)ptr
);
1052 EXPORT_SYMBOL(kmemleak_not_leak
);
1055 * kmemleak_ignore - ignore an allocated object
1056 * @ptr: pointer to beginning of the object
1058 * Calling this function on an object will cause the memory block to be
1059 * ignored (not scanned and not reported as a leak). This is usually done when
1060 * it is known that the corresponding block is not a leak and does not contain
1061 * any references to other allocated memory blocks.
1063 void __ref
kmemleak_ignore(const void *ptr
)
1065 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1067 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1068 make_black_object((unsigned long)ptr
);
1070 EXPORT_SYMBOL(kmemleak_ignore
);
1073 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1074 * @ptr: pointer to beginning or inside the object. This also
1075 * represents the start of the scan area
1076 * @size: size of the scan area
1077 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1079 * This function is used when it is known that only certain parts of an object
1080 * contain references to other objects. Kmemleak will only scan these areas
1081 * reducing the number false negatives.
1083 void __ref
kmemleak_scan_area(const void *ptr
, size_t size
, gfp_t gfp
)
1085 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1087 if (kmemleak_enabled
&& ptr
&& size
&& !IS_ERR(ptr
))
1088 add_scan_area((unsigned long)ptr
, size
, gfp
);
1090 EXPORT_SYMBOL(kmemleak_scan_area
);
1093 * kmemleak_no_scan - do not scan an allocated object
1094 * @ptr: pointer to beginning of the object
1096 * This function notifies kmemleak not to scan the given memory block. Useful
1097 * in situations where it is known that the given object does not contain any
1098 * references to other objects. Kmemleak will not scan such objects reducing
1099 * the number of false negatives.
1101 void __ref
kmemleak_no_scan(const void *ptr
)
1103 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1105 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1106 object_no_scan((unsigned long)ptr
);
1108 EXPORT_SYMBOL(kmemleak_no_scan
);
1111 * kmemleak_alloc_phys - similar to kmemleak_alloc but taking a physical
1113 * @phys: physical address of the object
1114 * @size: size of the object
1115 * @min_count: minimum number of references to this object.
1116 * See kmemleak_alloc()
1117 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1119 void __ref
kmemleak_alloc_phys(phys_addr_t phys
, size_t size
, int min_count
,
1122 if (!IS_ENABLED(CONFIG_HIGHMEM
) || PHYS_PFN(phys
) < max_low_pfn
)
1123 kmemleak_alloc(__va(phys
), size
, min_count
, gfp
);
1125 EXPORT_SYMBOL(kmemleak_alloc_phys
);
1128 * kmemleak_free_part_phys - similar to kmemleak_free_part but taking a
1129 * physical address argument
1130 * @phys: physical address if the beginning or inside an object. This
1131 * also represents the start of the range to be freed
1132 * @size: size to be unregistered
1134 void __ref
kmemleak_free_part_phys(phys_addr_t phys
, size_t size
)
1136 if (!IS_ENABLED(CONFIG_HIGHMEM
) || PHYS_PFN(phys
) < max_low_pfn
)
1137 kmemleak_free_part(__va(phys
), size
);
1139 EXPORT_SYMBOL(kmemleak_free_part_phys
);
1142 * kmemleak_not_leak_phys - similar to kmemleak_not_leak but taking a physical
1144 * @phys: physical address of the object
1146 void __ref
kmemleak_not_leak_phys(phys_addr_t phys
)
1148 if (!IS_ENABLED(CONFIG_HIGHMEM
) || PHYS_PFN(phys
) < max_low_pfn
)
1149 kmemleak_not_leak(__va(phys
));
1151 EXPORT_SYMBOL(kmemleak_not_leak_phys
);
1154 * kmemleak_ignore_phys - similar to kmemleak_ignore but taking a physical
1156 * @phys: physical address of the object
1158 void __ref
kmemleak_ignore_phys(phys_addr_t phys
)
1160 if (!IS_ENABLED(CONFIG_HIGHMEM
) || PHYS_PFN(phys
) < max_low_pfn
)
1161 kmemleak_ignore(__va(phys
));
1163 EXPORT_SYMBOL(kmemleak_ignore_phys
);
1166 * Update an object's checksum and return true if it was modified.
1168 static bool update_checksum(struct kmemleak_object
*object
)
1170 u32 old_csum
= object
->checksum
;
1172 kasan_disable_current();
1173 kcsan_disable_current();
1174 object
->checksum
= crc32(0, (void *)object
->pointer
, object
->size
);
1175 kasan_enable_current();
1176 kcsan_enable_current();
1178 return object
->checksum
!= old_csum
;
1182 * Update an object's references. object->lock must be held by the caller.
1184 static void update_refs(struct kmemleak_object
*object
)
1186 if (!color_white(object
)) {
1187 /* non-orphan, ignored or new */
1192 * Increase the object's reference count (number of pointers to the
1193 * memory block). If this count reaches the required minimum, the
1194 * object's color will become gray and it will be added to the
1198 if (color_gray(object
)) {
1199 /* put_object() called when removing from gray_list */
1200 WARN_ON(!get_object(object
));
1201 list_add_tail(&object
->gray_list
, &gray_list
);
1206 * Memory scanning is a long process and it needs to be interruptible. This
1207 * function checks whether such interrupt condition occurred.
1209 static int scan_should_stop(void)
1211 if (!kmemleak_enabled
)
1215 * This function may be called from either process or kthread context,
1216 * hence the need to check for both stop conditions.
1219 return signal_pending(current
);
1221 return kthread_should_stop();
1227 * Scan a memory block (exclusive range) for valid pointers and add those
1228 * found to the gray list.
1230 static void scan_block(void *_start
, void *_end
,
1231 struct kmemleak_object
*scanned
)
1234 unsigned long *start
= PTR_ALIGN(_start
, BYTES_PER_POINTER
);
1235 unsigned long *end
= _end
- (BYTES_PER_POINTER
- 1);
1236 unsigned long flags
;
1237 unsigned long untagged_ptr
;
1239 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
1240 for (ptr
= start
; ptr
< end
; ptr
++) {
1241 struct kmemleak_object
*object
;
1242 unsigned long pointer
;
1243 unsigned long excess_ref
;
1245 if (scan_should_stop())
1248 kasan_disable_current();
1250 kasan_enable_current();
1252 untagged_ptr
= (unsigned long)kasan_reset_tag((void *)pointer
);
1253 if (untagged_ptr
< min_addr
|| untagged_ptr
>= max_addr
)
1257 * No need for get_object() here since we hold kmemleak_lock.
1258 * object->use_count cannot be dropped to 0 while the object
1259 * is still present in object_tree_root and object_list
1260 * (with updates protected by kmemleak_lock).
1262 object
= lookup_object(pointer
, 1);
1265 if (object
== scanned
)
1266 /* self referenced, ignore */
1270 * Avoid the lockdep recursive warning on object->lock being
1271 * previously acquired in scan_object(). These locks are
1272 * enclosed by scan_mutex.
1274 raw_spin_lock_nested(&object
->lock
, SINGLE_DEPTH_NESTING
);
1275 /* only pass surplus references (object already gray) */
1276 if (color_gray(object
)) {
1277 excess_ref
= object
->excess_ref
;
1278 /* no need for update_refs() if object already gray */
1281 update_refs(object
);
1283 raw_spin_unlock(&object
->lock
);
1286 object
= lookup_object(excess_ref
, 0);
1289 if (object
== scanned
)
1290 /* circular reference, ignore */
1292 raw_spin_lock_nested(&object
->lock
, SINGLE_DEPTH_NESTING
);
1293 update_refs(object
);
1294 raw_spin_unlock(&object
->lock
);
1297 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
1301 * Scan a large memory block in MAX_SCAN_SIZE chunks to reduce the latency.
1304 static void scan_large_block(void *start
, void *end
)
1308 while (start
< end
) {
1309 next
= min(start
+ MAX_SCAN_SIZE
, end
);
1310 scan_block(start
, next
, NULL
);
1318 * Scan a memory block corresponding to a kmemleak_object. A condition is
1319 * that object->use_count >= 1.
1321 static void scan_object(struct kmemleak_object
*object
)
1323 struct kmemleak_scan_area
*area
;
1324 unsigned long flags
;
1327 * Once the object->lock is acquired, the corresponding memory block
1328 * cannot be freed (the same lock is acquired in delete_object).
1330 raw_spin_lock_irqsave(&object
->lock
, flags
);
1331 if (object
->flags
& OBJECT_NO_SCAN
)
1333 if (!(object
->flags
& OBJECT_ALLOCATED
))
1334 /* already freed object */
1336 if (hlist_empty(&object
->area_list
) ||
1337 object
->flags
& OBJECT_FULL_SCAN
) {
1338 void *start
= (void *)object
->pointer
;
1339 void *end
= (void *)(object
->pointer
+ object
->size
);
1343 next
= min(start
+ MAX_SCAN_SIZE
, end
);
1344 scan_block(start
, next
, object
);
1350 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1352 raw_spin_lock_irqsave(&object
->lock
, flags
);
1353 } while (object
->flags
& OBJECT_ALLOCATED
);
1355 hlist_for_each_entry(area
, &object
->area_list
, node
)
1356 scan_block((void *)area
->start
,
1357 (void *)(area
->start
+ area
->size
),
1360 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1364 * Scan the objects already referenced (gray objects). More objects will be
1365 * referenced and, if there are no memory leaks, all the objects are scanned.
1367 static void scan_gray_list(void)
1369 struct kmemleak_object
*object
, *tmp
;
1372 * The list traversal is safe for both tail additions and removals
1373 * from inside the loop. The kmemleak objects cannot be freed from
1374 * outside the loop because their use_count was incremented.
1376 object
= list_entry(gray_list
.next
, typeof(*object
), gray_list
);
1377 while (&object
->gray_list
!= &gray_list
) {
1380 /* may add new objects to the list */
1381 if (!scan_should_stop())
1382 scan_object(object
);
1384 tmp
= list_entry(object
->gray_list
.next
, typeof(*object
),
1387 /* remove the object from the list and release it */
1388 list_del(&object
->gray_list
);
1393 WARN_ON(!list_empty(&gray_list
));
1397 * Scan data sections and all the referenced memory blocks allocated via the
1398 * kernel's standard allocators. This function must be called with the
1401 static void kmemleak_scan(void)
1403 unsigned long flags
;
1404 struct kmemleak_object
*object
;
1408 jiffies_last_scan
= jiffies
;
1410 /* prepare the kmemleak_object's */
1412 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1413 raw_spin_lock_irqsave(&object
->lock
, flags
);
1416 * With a few exceptions there should be a maximum of
1417 * 1 reference to any object at this point.
1419 if (atomic_read(&object
->use_count
) > 1) {
1420 pr_debug("object->use_count = %d\n",
1421 atomic_read(&object
->use_count
));
1422 dump_object_info(object
);
1425 /* reset the reference count (whiten the object) */
1427 if (color_gray(object
) && get_object(object
))
1428 list_add_tail(&object
->gray_list
, &gray_list
);
1430 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1435 /* per-cpu sections scanning */
1436 for_each_possible_cpu(i
)
1437 scan_large_block(__per_cpu_start
+ per_cpu_offset(i
),
1438 __per_cpu_end
+ per_cpu_offset(i
));
1442 * Struct page scanning for each node.
1445 for_each_online_node(i
) {
1446 unsigned long start_pfn
= node_start_pfn(i
);
1447 unsigned long end_pfn
= node_end_pfn(i
);
1450 for (pfn
= start_pfn
; pfn
< end_pfn
; pfn
++) {
1451 struct page
*page
= pfn_to_online_page(pfn
);
1456 /* only scan pages belonging to this node */
1457 if (page_to_nid(page
) != i
)
1459 /* only scan if page is in use */
1460 if (page_count(page
) == 0)
1462 scan_block(page
, page
+ 1, NULL
);
1470 * Scanning the task stacks (may introduce false negatives).
1472 if (kmemleak_stack_scan
) {
1473 struct task_struct
*p
, *g
;
1476 for_each_process_thread(g
, p
) {
1477 void *stack
= try_get_task_stack(p
);
1479 scan_block(stack
, stack
+ THREAD_SIZE
, NULL
);
1487 * Scan the objects already referenced from the sections scanned
1493 * Check for new or unreferenced objects modified since the previous
1494 * scan and color them gray until the next scan.
1497 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1498 raw_spin_lock_irqsave(&object
->lock
, flags
);
1499 if (color_white(object
) && (object
->flags
& OBJECT_ALLOCATED
)
1500 && update_checksum(object
) && get_object(object
)) {
1501 /* color it gray temporarily */
1502 object
->count
= object
->min_count
;
1503 list_add_tail(&object
->gray_list
, &gray_list
);
1505 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1510 * Re-scan the gray list for modified unreferenced objects.
1515 * If scanning was stopped do not report any new unreferenced objects.
1517 if (scan_should_stop())
1521 * Scanning result reporting.
1524 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1525 raw_spin_lock_irqsave(&object
->lock
, flags
);
1526 if (unreferenced_object(object
) &&
1527 !(object
->flags
& OBJECT_REPORTED
)) {
1528 object
->flags
|= OBJECT_REPORTED
;
1530 if (kmemleak_verbose
)
1531 print_unreferenced(NULL
, object
);
1535 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1540 kmemleak_found_leaks
= true;
1542 pr_info("%d new suspected memory leaks (see /sys/kernel/debug/kmemleak)\n",
1549 * Thread function performing automatic memory scanning. Unreferenced objects
1550 * at the end of a memory scan are reported but only the first time.
1552 static int kmemleak_scan_thread(void *arg
)
1554 static int first_run
= IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN
);
1556 pr_info("Automatic memory scanning thread started\n");
1557 set_user_nice(current
, 10);
1560 * Wait before the first scan to allow the system to fully initialize.
1563 signed long timeout
= msecs_to_jiffies(SECS_FIRST_SCAN
* 1000);
1565 while (timeout
&& !kthread_should_stop())
1566 timeout
= schedule_timeout_interruptible(timeout
);
1569 while (!kthread_should_stop()) {
1570 signed long timeout
= jiffies_scan_wait
;
1572 mutex_lock(&scan_mutex
);
1574 mutex_unlock(&scan_mutex
);
1576 /* wait before the next scan */
1577 while (timeout
&& !kthread_should_stop())
1578 timeout
= schedule_timeout_interruptible(timeout
);
1581 pr_info("Automatic memory scanning thread ended\n");
1587 * Start the automatic memory scanning thread. This function must be called
1588 * with the scan_mutex held.
1590 static void start_scan_thread(void)
1594 scan_thread
= kthread_run(kmemleak_scan_thread
, NULL
, "kmemleak");
1595 if (IS_ERR(scan_thread
)) {
1596 pr_warn("Failed to create the scan thread\n");
1602 * Stop the automatic memory scanning thread.
1604 static void stop_scan_thread(void)
1607 kthread_stop(scan_thread
);
1613 * Iterate over the object_list and return the first valid object at or after
1614 * the required position with its use_count incremented. The function triggers
1615 * a memory scanning when the pos argument points to the first position.
1617 static void *kmemleak_seq_start(struct seq_file
*seq
, loff_t
*pos
)
1619 struct kmemleak_object
*object
;
1623 err
= mutex_lock_interruptible(&scan_mutex
);
1625 return ERR_PTR(err
);
1628 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1631 if (get_object(object
))
1640 * Return the next object in the object_list. The function decrements the
1641 * use_count of the previous object and increases that of the next one.
1643 static void *kmemleak_seq_next(struct seq_file
*seq
, void *v
, loff_t
*pos
)
1645 struct kmemleak_object
*prev_obj
= v
;
1646 struct kmemleak_object
*next_obj
= NULL
;
1647 struct kmemleak_object
*obj
= prev_obj
;
1651 list_for_each_entry_continue_rcu(obj
, &object_list
, object_list
) {
1652 if (get_object(obj
)) {
1658 put_object(prev_obj
);
1663 * Decrement the use_count of the last object required, if any.
1665 static void kmemleak_seq_stop(struct seq_file
*seq
, void *v
)
1669 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1670 * waiting was interrupted, so only release it if !IS_ERR.
1673 mutex_unlock(&scan_mutex
);
1680 * Print the information for an unreferenced object to the seq file.
1682 static int kmemleak_seq_show(struct seq_file
*seq
, void *v
)
1684 struct kmemleak_object
*object
= v
;
1685 unsigned long flags
;
1687 raw_spin_lock_irqsave(&object
->lock
, flags
);
1688 if ((object
->flags
& OBJECT_REPORTED
) && unreferenced_object(object
))
1689 print_unreferenced(seq
, object
);
1690 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1694 static const struct seq_operations kmemleak_seq_ops
= {
1695 .start
= kmemleak_seq_start
,
1696 .next
= kmemleak_seq_next
,
1697 .stop
= kmemleak_seq_stop
,
1698 .show
= kmemleak_seq_show
,
1701 static int kmemleak_open(struct inode
*inode
, struct file
*file
)
1703 return seq_open(file
, &kmemleak_seq_ops
);
1706 static int dump_str_object_info(const char *str
)
1708 unsigned long flags
;
1709 struct kmemleak_object
*object
;
1712 if (kstrtoul(str
, 0, &addr
))
1714 object
= find_and_get_object(addr
, 0);
1716 pr_info("Unknown object at 0x%08lx\n", addr
);
1720 raw_spin_lock_irqsave(&object
->lock
, flags
);
1721 dump_object_info(object
);
1722 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1729 * We use grey instead of black to ensure we can do future scans on the same
1730 * objects. If we did not do future scans these black objects could
1731 * potentially contain references to newly allocated objects in the future and
1732 * we'd end up with false positives.
1734 static void kmemleak_clear(void)
1736 struct kmemleak_object
*object
;
1737 unsigned long flags
;
1740 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1741 raw_spin_lock_irqsave(&object
->lock
, flags
);
1742 if ((object
->flags
& OBJECT_REPORTED
) &&
1743 unreferenced_object(object
))
1744 __paint_it(object
, KMEMLEAK_GREY
);
1745 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1749 kmemleak_found_leaks
= false;
1752 static void __kmemleak_do_cleanup(void);
1755 * File write operation to configure kmemleak at run-time. The following
1756 * commands can be written to the /sys/kernel/debug/kmemleak file:
1757 * off - disable kmemleak (irreversible)
1758 * stack=on - enable the task stacks scanning
1759 * stack=off - disable the tasks stacks scanning
1760 * scan=on - start the automatic memory scanning thread
1761 * scan=off - stop the automatic memory scanning thread
1762 * scan=... - set the automatic memory scanning period in seconds (0 to
1764 * scan - trigger a memory scan
1765 * clear - mark all current reported unreferenced kmemleak objects as
1766 * grey to ignore printing them, or free all kmemleak objects
1767 * if kmemleak has been disabled.
1768 * dump=... - dump information about the object found at the given address
1770 static ssize_t
kmemleak_write(struct file
*file
, const char __user
*user_buf
,
1771 size_t size
, loff_t
*ppos
)
1777 buf_size
= min(size
, (sizeof(buf
) - 1));
1778 if (strncpy_from_user(buf
, user_buf
, buf_size
) < 0)
1782 ret
= mutex_lock_interruptible(&scan_mutex
);
1786 if (strncmp(buf
, "clear", 5) == 0) {
1787 if (kmemleak_enabled
)
1790 __kmemleak_do_cleanup();
1794 if (!kmemleak_enabled
) {
1799 if (strncmp(buf
, "off", 3) == 0)
1801 else if (strncmp(buf
, "stack=on", 8) == 0)
1802 kmemleak_stack_scan
= 1;
1803 else if (strncmp(buf
, "stack=off", 9) == 0)
1804 kmemleak_stack_scan
= 0;
1805 else if (strncmp(buf
, "scan=on", 7) == 0)
1806 start_scan_thread();
1807 else if (strncmp(buf
, "scan=off", 8) == 0)
1809 else if (strncmp(buf
, "scan=", 5) == 0) {
1812 ret
= kstrtoul(buf
+ 5, 0, &secs
);
1817 jiffies_scan_wait
= msecs_to_jiffies(secs
* 1000);
1818 start_scan_thread();
1820 } else if (strncmp(buf
, "scan", 4) == 0)
1822 else if (strncmp(buf
, "dump=", 5) == 0)
1823 ret
= dump_str_object_info(buf
+ 5);
1828 mutex_unlock(&scan_mutex
);
1832 /* ignore the rest of the buffer, only one command at a time */
1837 static const struct file_operations kmemleak_fops
= {
1838 .owner
= THIS_MODULE
,
1839 .open
= kmemleak_open
,
1841 .write
= kmemleak_write
,
1842 .llseek
= seq_lseek
,
1843 .release
= seq_release
,
1846 static void __kmemleak_do_cleanup(void)
1848 struct kmemleak_object
*object
, *tmp
;
1851 * Kmemleak has already been disabled, no need for RCU list traversal
1852 * or kmemleak_lock held.
1854 list_for_each_entry_safe(object
, tmp
, &object_list
, object_list
) {
1855 __remove_object(object
);
1856 __delete_object(object
);
1861 * Stop the memory scanning thread and free the kmemleak internal objects if
1862 * no previous scan thread (otherwise, kmemleak may still have some useful
1863 * information on memory leaks).
1865 static void kmemleak_do_cleanup(struct work_struct
*work
)
1869 mutex_lock(&scan_mutex
);
1871 * Once it is made sure that kmemleak_scan has stopped, it is safe to no
1872 * longer track object freeing. Ordering of the scan thread stopping and
1873 * the memory accesses below is guaranteed by the kthread_stop()
1876 kmemleak_free_enabled
= 0;
1877 mutex_unlock(&scan_mutex
);
1879 if (!kmemleak_found_leaks
)
1880 __kmemleak_do_cleanup();
1882 pr_info("Kmemleak disabled without freeing internal data. Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\".\n");
1885 static DECLARE_WORK(cleanup_work
, kmemleak_do_cleanup
);
1888 * Disable kmemleak. No memory allocation/freeing will be traced once this
1889 * function is called. Disabling kmemleak is an irreversible operation.
1891 static void kmemleak_disable(void)
1893 /* atomically check whether it was already invoked */
1894 if (cmpxchg(&kmemleak_error
, 0, 1))
1897 /* stop any memory operation tracing */
1898 kmemleak_enabled
= 0;
1900 /* check whether it is too early for a kernel thread */
1901 if (kmemleak_initialized
)
1902 schedule_work(&cleanup_work
);
1904 kmemleak_free_enabled
= 0;
1906 pr_info("Kernel memory leak detector disabled\n");
1910 * Allow boot-time kmemleak disabling (enabled by default).
1912 static int __init
kmemleak_boot_config(char *str
)
1916 if (strcmp(str
, "off") == 0)
1918 else if (strcmp(str
, "on") == 0)
1919 kmemleak_skip_disable
= 1;
1924 early_param("kmemleak", kmemleak_boot_config
);
1927 * Kmemleak initialization.
1929 void __init
kmemleak_init(void)
1931 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1932 if (!kmemleak_skip_disable
) {
1941 jiffies_min_age
= msecs_to_jiffies(MSECS_MIN_AGE
);
1942 jiffies_scan_wait
= msecs_to_jiffies(SECS_SCAN_WAIT
* 1000);
1944 object_cache
= KMEM_CACHE(kmemleak_object
, SLAB_NOLEAKTRACE
);
1945 scan_area_cache
= KMEM_CACHE(kmemleak_scan_area
, SLAB_NOLEAKTRACE
);
1947 /* register the data/bss sections */
1948 create_object((unsigned long)_sdata
, _edata
- _sdata
,
1949 KMEMLEAK_GREY
, GFP_ATOMIC
);
1950 create_object((unsigned long)__bss_start
, __bss_stop
- __bss_start
,
1951 KMEMLEAK_GREY
, GFP_ATOMIC
);
1952 /* only register .data..ro_after_init if not within .data */
1953 if (&__start_ro_after_init
< &_sdata
|| &__end_ro_after_init
> &_edata
)
1954 create_object((unsigned long)__start_ro_after_init
,
1955 __end_ro_after_init
- __start_ro_after_init
,
1956 KMEMLEAK_GREY
, GFP_ATOMIC
);
1960 * Late initialization function.
1962 static int __init
kmemleak_late_init(void)
1964 kmemleak_initialized
= 1;
1966 debugfs_create_file("kmemleak", 0644, NULL
, NULL
, &kmemleak_fops
);
1968 if (kmemleak_error
) {
1970 * Some error occurred and kmemleak was disabled. There is a
1971 * small chance that kmemleak_disable() was called immediately
1972 * after setting kmemleak_initialized and we may end up with
1973 * two clean-up threads but serialized by scan_mutex.
1975 schedule_work(&cleanup_work
);
1979 if (IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN
)) {
1980 mutex_lock(&scan_mutex
);
1981 start_scan_thread();
1982 mutex_unlock(&scan_mutex
);
1985 pr_info("Kernel memory leak detector initialized (mem pool available: %d)\n",
1986 mem_pool_free_count
);
1990 late_initcall(kmemleak_late_init
);