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_NOLOCKDEP)) | \
118 __GFP_NORETRY | __GFP_NOMEMALLOC | \
121 /* scanning area inside a memory block */
122 struct kmemleak_scan_area
{
123 struct hlist_node node
;
128 #define KMEMLEAK_GREY 0
129 #define KMEMLEAK_BLACK -1
132 * Structure holding the metadata for each allocated memory block.
133 * Modifications to such objects should be made while holding the
134 * object->lock. Insertions or deletions from object_list, gray_list or
135 * rb_node are already protected by the corresponding locks or mutex (see
136 * the notes on locking above). These objects are reference-counted
137 * (use_count) and freed using the RCU mechanism.
139 struct kmemleak_object
{
141 unsigned int flags
; /* object status flags */
142 struct list_head object_list
;
143 struct list_head gray_list
;
144 struct rb_node rb_node
;
145 struct rcu_head rcu
; /* object_list lockless traversal */
146 /* object usage count; object freed when use_count == 0 */
148 unsigned long pointer
;
150 /* pass surplus references to this pointer */
151 unsigned long excess_ref
;
152 /* minimum number of a pointers found before it is considered leak */
154 /* the total number of pointers found pointing to this object */
156 /* checksum for detecting modified objects */
158 /* memory ranges to be scanned inside an object (empty for all) */
159 struct hlist_head area_list
;
160 unsigned long trace
[MAX_TRACE
];
161 unsigned int trace_len
;
162 unsigned long jiffies
; /* creation timestamp */
163 pid_t pid
; /* pid of the current task */
164 char comm
[TASK_COMM_LEN
]; /* executable name */
167 /* flag representing the memory block allocation status */
168 #define OBJECT_ALLOCATED (1 << 0)
169 /* flag set after the first reporting of an unreference object */
170 #define OBJECT_REPORTED (1 << 1)
171 /* flag set to not scan the object */
172 #define OBJECT_NO_SCAN (1 << 2)
173 /* flag set to fully scan the object when scan_area allocation failed */
174 #define OBJECT_FULL_SCAN (1 << 3)
176 #define HEX_PREFIX " "
177 /* number of bytes to print per line; must be 16 or 32 */
178 #define HEX_ROW_SIZE 16
179 /* number of bytes to print at a time (1, 2, 4, 8) */
180 #define HEX_GROUP_SIZE 1
181 /* include ASCII after the hex output */
183 /* max number of lines to be printed */
184 #define HEX_MAX_LINES 2
186 /* the list of all allocated objects */
187 static LIST_HEAD(object_list
);
188 /* the list of gray-colored objects (see color_gray comment below) */
189 static LIST_HEAD(gray_list
);
190 /* memory pool allocation */
191 static struct kmemleak_object mem_pool
[CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE
];
192 static int mem_pool_free_count
= ARRAY_SIZE(mem_pool
);
193 static LIST_HEAD(mem_pool_free_list
);
194 /* search tree for object boundaries */
195 static struct rb_root object_tree_root
= RB_ROOT
;
196 /* protecting the access to object_list and object_tree_root */
197 static DEFINE_RAW_SPINLOCK(kmemleak_lock
);
199 /* allocation caches for kmemleak internal data */
200 static struct kmem_cache
*object_cache
;
201 static struct kmem_cache
*scan_area_cache
;
203 /* set if tracing memory operations is enabled */
204 static int kmemleak_enabled
= 1;
205 /* same as above but only for the kmemleak_free() callback */
206 static int kmemleak_free_enabled
= 1;
207 /* set in the late_initcall if there were no errors */
208 static int kmemleak_initialized
;
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 unsigned 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
;
233 static bool kmemleak_verbose
;
234 module_param_named(verbose
, kmemleak_verbose
, bool, 0600);
236 static void kmemleak_disable(void);
239 * Print a warning and dump the stack trace.
241 #define kmemleak_warn(x...) do { \
244 kmemleak_warning = 1; \
248 * Macro invoked when a serious kmemleak condition occurred and cannot be
249 * recovered from. Kmemleak will be disabled and further allocation/freeing
250 * tracing no longer available.
252 #define kmemleak_stop(x...) do { \
254 kmemleak_disable(); \
257 #define warn_or_seq_printf(seq, fmt, ...) do { \
259 seq_printf(seq, fmt, ##__VA_ARGS__); \
261 pr_warn(fmt, ##__VA_ARGS__); \
264 static void warn_or_seq_hex_dump(struct seq_file
*seq
, int prefix_type
,
265 int rowsize
, int groupsize
, const void *buf
,
266 size_t len
, bool ascii
)
269 seq_hex_dump(seq
, HEX_PREFIX
, prefix_type
, rowsize
, groupsize
,
272 print_hex_dump(KERN_WARNING
, pr_fmt(HEX_PREFIX
), prefix_type
,
273 rowsize
, groupsize
, buf
, len
, ascii
);
277 * Printing of the objects hex dump to the seq file. The number of lines to be
278 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
279 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
280 * with the object->lock held.
282 static void hex_dump_object(struct seq_file
*seq
,
283 struct kmemleak_object
*object
)
285 const u8
*ptr
= (const u8
*)object
->pointer
;
288 /* limit the number of lines to HEX_MAX_LINES */
289 len
= min_t(size_t, object
->size
, HEX_MAX_LINES
* HEX_ROW_SIZE
);
291 warn_or_seq_printf(seq
, " hex dump (first %zu bytes):\n", len
);
292 kasan_disable_current();
293 warn_or_seq_hex_dump(seq
, DUMP_PREFIX_NONE
, HEX_ROW_SIZE
,
294 HEX_GROUP_SIZE
, kasan_reset_tag((void *)ptr
), len
, HEX_ASCII
);
295 kasan_enable_current();
299 * Object colors, encoded with count and min_count:
300 * - white - orphan object, not enough references to it (count < min_count)
301 * - gray - not orphan, not marked as false positive (min_count == 0) or
302 * sufficient references to it (count >= min_count)
303 * - black - ignore, it doesn't contain references (e.g. text section)
304 * (min_count == -1). No function defined for this color.
305 * Newly created objects don't have any color assigned (object->count == -1)
306 * before the next memory scan when they become white.
308 static bool color_white(const struct kmemleak_object
*object
)
310 return object
->count
!= KMEMLEAK_BLACK
&&
311 object
->count
< object
->min_count
;
314 static bool color_gray(const struct kmemleak_object
*object
)
316 return object
->min_count
!= KMEMLEAK_BLACK
&&
317 object
->count
>= object
->min_count
;
321 * Objects are considered unreferenced only if their color is white, they have
322 * not be deleted and have a minimum age to avoid false positives caused by
323 * pointers temporarily stored in CPU registers.
325 static bool unreferenced_object(struct kmemleak_object
*object
)
327 return (color_white(object
) && object
->flags
& OBJECT_ALLOCATED
) &&
328 time_before_eq(object
->jiffies
+ jiffies_min_age
,
333 * Printing of the unreferenced objects information to the seq file. The
334 * print_unreferenced function must be called with the object->lock held.
336 static void print_unreferenced(struct seq_file
*seq
,
337 struct kmemleak_object
*object
)
340 unsigned int msecs_age
= jiffies_to_msecs(jiffies
- object
->jiffies
);
342 warn_or_seq_printf(seq
, "unreferenced object 0x%08lx (size %zu):\n",
343 object
->pointer
, object
->size
);
344 warn_or_seq_printf(seq
, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
345 object
->comm
, object
->pid
, object
->jiffies
,
346 msecs_age
/ 1000, msecs_age
% 1000);
347 hex_dump_object(seq
, object
);
348 warn_or_seq_printf(seq
, " backtrace:\n");
350 for (i
= 0; i
< object
->trace_len
; i
++) {
351 void *ptr
= (void *)object
->trace
[i
];
352 warn_or_seq_printf(seq
, " [<%p>] %pS\n", ptr
, ptr
);
357 * Print the kmemleak_object information. This function is used mainly for
358 * debugging special cases when kmemleak operations. It must be called with
359 * the object->lock held.
361 static void dump_object_info(struct kmemleak_object
*object
)
363 pr_notice("Object 0x%08lx (size %zu):\n",
364 object
->pointer
, object
->size
);
365 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
366 object
->comm
, object
->pid
, object
->jiffies
);
367 pr_notice(" min_count = %d\n", object
->min_count
);
368 pr_notice(" count = %d\n", object
->count
);
369 pr_notice(" flags = 0x%x\n", object
->flags
);
370 pr_notice(" checksum = %u\n", object
->checksum
);
371 pr_notice(" backtrace:\n");
372 stack_trace_print(object
->trace
, object
->trace_len
, 4);
376 * Look-up a memory block metadata (kmemleak_object) in the object search
377 * tree based on a pointer value. If alias is 0, only values pointing to the
378 * beginning of the memory block are allowed. The kmemleak_lock must be held
379 * when calling this function.
381 static struct kmemleak_object
*lookup_object(unsigned long ptr
, int alias
)
383 struct rb_node
*rb
= object_tree_root
.rb_node
;
386 struct kmemleak_object
*object
=
387 rb_entry(rb
, struct kmemleak_object
, rb_node
);
388 if (ptr
< object
->pointer
)
389 rb
= object
->rb_node
.rb_left
;
390 else if (object
->pointer
+ object
->size
<= ptr
)
391 rb
= object
->rb_node
.rb_right
;
392 else if (object
->pointer
== ptr
|| alias
)
395 kmemleak_warn("Found object by alias at 0x%08lx\n",
397 dump_object_info(object
);
405 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
406 * that once an object's use_count reached 0, the RCU freeing was already
407 * registered and the object should no longer be used. This function must be
408 * called under the protection of rcu_read_lock().
410 static int get_object(struct kmemleak_object
*object
)
412 return atomic_inc_not_zero(&object
->use_count
);
416 * Memory pool allocation and freeing. kmemleak_lock must not be held.
418 static struct kmemleak_object
*mem_pool_alloc(gfp_t gfp
)
421 struct kmemleak_object
*object
;
423 /* try the slab allocator first */
425 object
= kmem_cache_alloc(object_cache
, gfp_kmemleak_mask(gfp
));
430 /* slab allocation failed, try the memory pool */
431 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
432 object
= list_first_entry_or_null(&mem_pool_free_list
,
433 typeof(*object
), object_list
);
435 list_del(&object
->object_list
);
436 else if (mem_pool_free_count
)
437 object
= &mem_pool
[--mem_pool_free_count
];
439 pr_warn_once("Memory pool empty, consider increasing CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE\n");
440 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
446 * Return the object to either the slab allocator or the memory pool.
448 static void mem_pool_free(struct kmemleak_object
*object
)
452 if (object
< mem_pool
|| object
>= mem_pool
+ ARRAY_SIZE(mem_pool
)) {
453 kmem_cache_free(object_cache
, object
);
457 /* add the object to the memory pool free list */
458 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
459 list_add(&object
->object_list
, &mem_pool_free_list
);
460 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
464 * RCU callback to free a kmemleak_object.
466 static void free_object_rcu(struct rcu_head
*rcu
)
468 struct hlist_node
*tmp
;
469 struct kmemleak_scan_area
*area
;
470 struct kmemleak_object
*object
=
471 container_of(rcu
, struct kmemleak_object
, rcu
);
474 * Once use_count is 0 (guaranteed by put_object), there is no other
475 * code accessing this object, hence no need for locking.
477 hlist_for_each_entry_safe(area
, tmp
, &object
->area_list
, node
) {
478 hlist_del(&area
->node
);
479 kmem_cache_free(scan_area_cache
, area
);
481 mem_pool_free(object
);
485 * Decrement the object use_count. Once the count is 0, free the object using
486 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
487 * delete_object() path, the delayed RCU freeing ensures that there is no
488 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
491 static void put_object(struct kmemleak_object
*object
)
493 if (!atomic_dec_and_test(&object
->use_count
))
496 /* should only get here after delete_object was called */
497 WARN_ON(object
->flags
& OBJECT_ALLOCATED
);
500 * It may be too early for the RCU callbacks, however, there is no
501 * concurrent object_list traversal when !object_cache and all objects
502 * came from the memory pool. Free the object directly.
505 call_rcu(&object
->rcu
, free_object_rcu
);
507 free_object_rcu(&object
->rcu
);
511 * Look up an object in the object search tree and increase its use_count.
513 static struct kmemleak_object
*find_and_get_object(unsigned long ptr
, int alias
)
516 struct kmemleak_object
*object
;
519 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
520 object
= lookup_object(ptr
, alias
);
521 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
523 /* check whether the object is still available */
524 if (object
&& !get_object(object
))
532 * Remove an object from the object_tree_root and object_list. Must be called
533 * with the kmemleak_lock held _if_ kmemleak is still enabled.
535 static void __remove_object(struct kmemleak_object
*object
)
537 rb_erase(&object
->rb_node
, &object_tree_root
);
538 list_del_rcu(&object
->object_list
);
542 * Look up an object in the object search tree and remove it from both
543 * object_tree_root and object_list. The returned object's use_count should be
544 * at least 1, as initially set by create_object().
546 static struct kmemleak_object
*find_and_remove_object(unsigned long ptr
, int alias
)
549 struct kmemleak_object
*object
;
551 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
552 object
= lookup_object(ptr
, alias
);
554 __remove_object(object
);
555 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
561 * Save stack trace to the given array of MAX_TRACE size.
563 static int __save_stack_trace(unsigned long *trace
)
565 return stack_trace_save(trace
, MAX_TRACE
, 2);
569 * Create the metadata (struct kmemleak_object) corresponding to an allocated
570 * memory block and add it to the object_list and object_tree_root.
572 static struct kmemleak_object
*create_object(unsigned long ptr
, size_t size
,
573 int min_count
, gfp_t gfp
)
576 struct kmemleak_object
*object
, *parent
;
577 struct rb_node
**link
, *rb_parent
;
578 unsigned long untagged_ptr
;
580 object
= mem_pool_alloc(gfp
);
582 pr_warn("Cannot allocate a kmemleak_object structure\n");
587 INIT_LIST_HEAD(&object
->object_list
);
588 INIT_LIST_HEAD(&object
->gray_list
);
589 INIT_HLIST_HEAD(&object
->area_list
);
590 raw_spin_lock_init(&object
->lock
);
591 atomic_set(&object
->use_count
, 1);
592 object
->flags
= OBJECT_ALLOCATED
;
593 object
->pointer
= ptr
;
594 object
->size
= kfence_ksize((void *)ptr
) ?: size
;
595 object
->excess_ref
= 0;
596 object
->min_count
= min_count
;
597 object
->count
= 0; /* white color initially */
598 object
->jiffies
= jiffies
;
599 object
->checksum
= 0;
601 /* task information */
604 strncpy(object
->comm
, "hardirq", sizeof(object
->comm
));
605 } else if (in_serving_softirq()) {
607 strncpy(object
->comm
, "softirq", sizeof(object
->comm
));
609 object
->pid
= current
->pid
;
611 * There is a small chance of a race with set_task_comm(),
612 * however using get_task_comm() here may cause locking
613 * dependency issues with current->alloc_lock. In the worst
614 * case, the command line is not correct.
616 strncpy(object
->comm
, current
->comm
, sizeof(object
->comm
));
619 /* kernel backtrace */
620 object
->trace_len
= __save_stack_trace(object
->trace
);
622 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
624 untagged_ptr
= (unsigned long)kasan_reset_tag((void *)ptr
);
625 min_addr
= min(min_addr
, untagged_ptr
);
626 max_addr
= max(max_addr
, untagged_ptr
+ size
);
627 link
= &object_tree_root
.rb_node
;
631 parent
= rb_entry(rb_parent
, struct kmemleak_object
, rb_node
);
632 if (ptr
+ size
<= parent
->pointer
)
633 link
= &parent
->rb_node
.rb_left
;
634 else if (parent
->pointer
+ parent
->size
<= ptr
)
635 link
= &parent
->rb_node
.rb_right
;
637 kmemleak_stop("Cannot insert 0x%lx into the object search tree (overlaps existing)\n",
640 * No need for parent->lock here since "parent" cannot
641 * be freed while the kmemleak_lock is held.
643 dump_object_info(parent
);
644 kmem_cache_free(object_cache
, object
);
649 rb_link_node(&object
->rb_node
, rb_parent
, link
);
650 rb_insert_color(&object
->rb_node
, &object_tree_root
);
652 list_add_tail_rcu(&object
->object_list
, &object_list
);
654 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
659 * Mark the object as not allocated and schedule RCU freeing via put_object().
661 static void __delete_object(struct kmemleak_object
*object
)
665 WARN_ON(!(object
->flags
& OBJECT_ALLOCATED
));
666 WARN_ON(atomic_read(&object
->use_count
) < 1);
669 * Locking here also ensures that the corresponding memory block
670 * cannot be freed when it is being scanned.
672 raw_spin_lock_irqsave(&object
->lock
, flags
);
673 object
->flags
&= ~OBJECT_ALLOCATED
;
674 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
679 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
682 static void delete_object_full(unsigned long ptr
)
684 struct kmemleak_object
*object
;
686 object
= find_and_remove_object(ptr
, 0);
689 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
694 __delete_object(object
);
698 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
699 * delete it. If the memory block is partially freed, the function may create
700 * additional metadata for the remaining parts of the block.
702 static void delete_object_part(unsigned long ptr
, size_t size
)
704 struct kmemleak_object
*object
;
705 unsigned long start
, end
;
707 object
= find_and_remove_object(ptr
, 1);
710 kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n",
717 * Create one or two objects that may result from the memory block
718 * split. Note that partial freeing is only done by free_bootmem() and
719 * this happens before kmemleak_init() is called.
721 start
= object
->pointer
;
722 end
= object
->pointer
+ object
->size
;
724 create_object(start
, ptr
- start
, object
->min_count
,
726 if (ptr
+ size
< end
)
727 create_object(ptr
+ size
, end
- ptr
- size
, object
->min_count
,
730 __delete_object(object
);
733 static void __paint_it(struct kmemleak_object
*object
, int color
)
735 object
->min_count
= color
;
736 if (color
== KMEMLEAK_BLACK
)
737 object
->flags
|= OBJECT_NO_SCAN
;
740 static void paint_it(struct kmemleak_object
*object
, int color
)
744 raw_spin_lock_irqsave(&object
->lock
, flags
);
745 __paint_it(object
, color
);
746 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
749 static void paint_ptr(unsigned long ptr
, int color
)
751 struct kmemleak_object
*object
;
753 object
= find_and_get_object(ptr
, 0);
755 kmemleak_warn("Trying to color unknown object at 0x%08lx as %s\n",
757 (color
== KMEMLEAK_GREY
) ? "Grey" :
758 (color
== KMEMLEAK_BLACK
) ? "Black" : "Unknown");
761 paint_it(object
, color
);
766 * Mark an object permanently as gray-colored so that it can no longer be
767 * reported as a leak. This is used in general to mark a false positive.
769 static void make_gray_object(unsigned long ptr
)
771 paint_ptr(ptr
, KMEMLEAK_GREY
);
775 * Mark the object as black-colored so that it is ignored from scans and
778 static void make_black_object(unsigned long ptr
)
780 paint_ptr(ptr
, KMEMLEAK_BLACK
);
784 * Add a scanning area to the object. If at least one such area is added,
785 * kmemleak will only scan these ranges rather than the whole memory block.
787 static void add_scan_area(unsigned long ptr
, size_t size
, gfp_t gfp
)
790 struct kmemleak_object
*object
;
791 struct kmemleak_scan_area
*area
= NULL
;
792 unsigned long untagged_ptr
;
793 unsigned long untagged_objp
;
795 object
= find_and_get_object(ptr
, 1);
797 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
802 untagged_ptr
= (unsigned long)kasan_reset_tag((void *)ptr
);
803 untagged_objp
= (unsigned long)kasan_reset_tag((void *)object
->pointer
);
806 area
= kmem_cache_alloc(scan_area_cache
, gfp_kmemleak_mask(gfp
));
808 raw_spin_lock_irqsave(&object
->lock
, flags
);
810 pr_warn_once("Cannot allocate a scan area, scanning the full object\n");
811 /* mark the object for full scan to avoid false positives */
812 object
->flags
|= OBJECT_FULL_SCAN
;
815 if (size
== SIZE_MAX
) {
816 size
= untagged_objp
+ object
->size
- untagged_ptr
;
817 } else if (untagged_ptr
+ size
> untagged_objp
+ object
->size
) {
818 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr
);
819 dump_object_info(object
);
820 kmem_cache_free(scan_area_cache
, area
);
824 INIT_HLIST_NODE(&area
->node
);
828 hlist_add_head(&area
->node
, &object
->area_list
);
830 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
835 * Any surplus references (object already gray) to 'ptr' are passed to
836 * 'excess_ref'. This is used in the vmalloc() case where a pointer to
837 * vm_struct may be used as an alternative reference to the vmalloc'ed object
838 * (see free_thread_stack()).
840 static void object_set_excess_ref(unsigned long ptr
, unsigned long excess_ref
)
843 struct kmemleak_object
*object
;
845 object
= find_and_get_object(ptr
, 0);
847 kmemleak_warn("Setting excess_ref on unknown object at 0x%08lx\n",
852 raw_spin_lock_irqsave(&object
->lock
, flags
);
853 object
->excess_ref
= excess_ref
;
854 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
859 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
860 * pointer. Such object will not be scanned by kmemleak but references to it
863 static void object_no_scan(unsigned long ptr
)
866 struct kmemleak_object
*object
;
868 object
= find_and_get_object(ptr
, 0);
870 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr
);
874 raw_spin_lock_irqsave(&object
->lock
, flags
);
875 object
->flags
|= OBJECT_NO_SCAN
;
876 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
881 * kmemleak_alloc - register a newly allocated object
882 * @ptr: pointer to beginning of the object
883 * @size: size of the object
884 * @min_count: minimum number of references to this object. If during memory
885 * scanning a number of references less than @min_count is found,
886 * the object is reported as a memory leak. If @min_count is 0,
887 * the object is never reported as a leak. If @min_count is -1,
888 * the object is ignored (not scanned and not reported as a leak)
889 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
891 * This function is called from the kernel allocators when a new object
892 * (memory block) is allocated (kmem_cache_alloc, kmalloc etc.).
894 void __ref
kmemleak_alloc(const void *ptr
, size_t size
, int min_count
,
897 pr_debug("%s(0x%p, %zu, %d)\n", __func__
, ptr
, size
, min_count
);
899 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
900 create_object((unsigned long)ptr
, size
, min_count
, gfp
);
902 EXPORT_SYMBOL_GPL(kmemleak_alloc
);
905 * kmemleak_alloc_percpu - register a newly allocated __percpu object
906 * @ptr: __percpu pointer to beginning of the object
907 * @size: size of the object
908 * @gfp: flags used for kmemleak internal memory allocations
910 * This function is called from the kernel percpu allocator when a new object
911 * (memory block) is allocated (alloc_percpu).
913 void __ref
kmemleak_alloc_percpu(const void __percpu
*ptr
, size_t size
,
918 pr_debug("%s(0x%p, %zu)\n", __func__
, ptr
, size
);
921 * Percpu allocations are only scanned and not reported as leaks
922 * (min_count is set to 0).
924 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
925 for_each_possible_cpu(cpu
)
926 create_object((unsigned long)per_cpu_ptr(ptr
, cpu
),
929 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu
);
932 * kmemleak_vmalloc - register a newly vmalloc'ed object
933 * @area: pointer to vm_struct
934 * @size: size of the object
935 * @gfp: __vmalloc() flags used for kmemleak internal memory allocations
937 * This function is called from the vmalloc() kernel allocator when a new
938 * object (memory block) is allocated.
940 void __ref
kmemleak_vmalloc(const struct vm_struct
*area
, size_t size
, gfp_t gfp
)
942 pr_debug("%s(0x%p, %zu)\n", __func__
, area
, size
);
945 * A min_count = 2 is needed because vm_struct contains a reference to
946 * the virtual address of the vmalloc'ed block.
948 if (kmemleak_enabled
) {
949 create_object((unsigned long)area
->addr
, size
, 2, gfp
);
950 object_set_excess_ref((unsigned long)area
,
951 (unsigned long)area
->addr
);
954 EXPORT_SYMBOL_GPL(kmemleak_vmalloc
);
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
);
970 EXPORT_SYMBOL_GPL(kmemleak_free
);
973 * kmemleak_free_part - partially unregister a previously registered object
974 * @ptr: pointer to the beginning or inside the object. This also
975 * represents the start of the range to be freed
976 * @size: size to be unregistered
978 * This function is called when only a part of a memory block is freed
979 * (usually from the bootmem allocator).
981 void __ref
kmemleak_free_part(const void *ptr
, size_t size
)
983 pr_debug("%s(0x%p)\n", __func__
, ptr
);
985 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
986 delete_object_part((unsigned long)ptr
, size
);
988 EXPORT_SYMBOL_GPL(kmemleak_free_part
);
991 * kmemleak_free_percpu - unregister a previously registered __percpu object
992 * @ptr: __percpu pointer to beginning of the object
994 * This function is called from the kernel percpu allocator when an object
995 * (memory block) is freed (free_percpu).
997 void __ref
kmemleak_free_percpu(const void __percpu
*ptr
)
1001 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1003 if (kmemleak_free_enabled
&& ptr
&& !IS_ERR(ptr
))
1004 for_each_possible_cpu(cpu
)
1005 delete_object_full((unsigned long)per_cpu_ptr(ptr
,
1008 EXPORT_SYMBOL_GPL(kmemleak_free_percpu
);
1011 * kmemleak_update_trace - update object allocation stack trace
1012 * @ptr: pointer to beginning of the object
1014 * Override the object allocation stack trace for cases where the actual
1015 * allocation place is not always useful.
1017 void __ref
kmemleak_update_trace(const void *ptr
)
1019 struct kmemleak_object
*object
;
1020 unsigned long flags
;
1022 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1024 if (!kmemleak_enabled
|| IS_ERR_OR_NULL(ptr
))
1027 object
= find_and_get_object((unsigned long)ptr
, 1);
1030 kmemleak_warn("Updating stack trace for unknown object at %p\n",
1036 raw_spin_lock_irqsave(&object
->lock
, flags
);
1037 object
->trace_len
= __save_stack_trace(object
->trace
);
1038 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1042 EXPORT_SYMBOL(kmemleak_update_trace
);
1045 * kmemleak_not_leak - mark an allocated object as false positive
1046 * @ptr: pointer to beginning of the object
1048 * Calling this function on an object will cause the memory block to no longer
1049 * be reported as leak and always be scanned.
1051 void __ref
kmemleak_not_leak(const void *ptr
)
1053 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1055 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1056 make_gray_object((unsigned long)ptr
);
1058 EXPORT_SYMBOL(kmemleak_not_leak
);
1061 * kmemleak_ignore - ignore an allocated object
1062 * @ptr: pointer to beginning of the object
1064 * Calling this function on an object will cause the memory block to be
1065 * ignored (not scanned and not reported as a leak). This is usually done when
1066 * it is known that the corresponding block is not a leak and does not contain
1067 * any references to other allocated memory blocks.
1069 void __ref
kmemleak_ignore(const void *ptr
)
1071 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1073 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1074 make_black_object((unsigned long)ptr
);
1076 EXPORT_SYMBOL(kmemleak_ignore
);
1079 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1080 * @ptr: pointer to beginning or inside the object. This also
1081 * represents the start of the scan area
1082 * @size: size of the scan area
1083 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1085 * This function is used when it is known that only certain parts of an object
1086 * contain references to other objects. Kmemleak will only scan these areas
1087 * reducing the number false negatives.
1089 void __ref
kmemleak_scan_area(const void *ptr
, size_t size
, gfp_t gfp
)
1091 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1093 if (kmemleak_enabled
&& ptr
&& size
&& !IS_ERR(ptr
))
1094 add_scan_area((unsigned long)ptr
, size
, gfp
);
1096 EXPORT_SYMBOL(kmemleak_scan_area
);
1099 * kmemleak_no_scan - do not scan an allocated object
1100 * @ptr: pointer to beginning of the object
1102 * This function notifies kmemleak not to scan the given memory block. Useful
1103 * in situations where it is known that the given object does not contain any
1104 * references to other objects. Kmemleak will not scan such objects reducing
1105 * the number of false negatives.
1107 void __ref
kmemleak_no_scan(const void *ptr
)
1109 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1111 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1112 object_no_scan((unsigned long)ptr
);
1114 EXPORT_SYMBOL(kmemleak_no_scan
);
1117 * kmemleak_alloc_phys - similar to kmemleak_alloc but taking a physical
1119 * @phys: physical address of the object
1120 * @size: size of the object
1121 * @min_count: minimum number of references to this object.
1122 * See kmemleak_alloc()
1123 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1125 void __ref
kmemleak_alloc_phys(phys_addr_t phys
, size_t size
, int min_count
,
1128 if (PHYS_PFN(phys
) >= min_low_pfn
&& PHYS_PFN(phys
) < max_low_pfn
)
1129 kmemleak_alloc(__va(phys
), size
, min_count
, gfp
);
1131 EXPORT_SYMBOL(kmemleak_alloc_phys
);
1134 * kmemleak_free_part_phys - similar to kmemleak_free_part but taking a
1135 * physical address argument
1136 * @phys: physical address if the beginning or inside an object. This
1137 * also represents the start of the range to be freed
1138 * @size: size to be unregistered
1140 void __ref
kmemleak_free_part_phys(phys_addr_t phys
, size_t size
)
1142 if (PHYS_PFN(phys
) >= min_low_pfn
&& PHYS_PFN(phys
) < max_low_pfn
)
1143 kmemleak_free_part(__va(phys
), size
);
1145 EXPORT_SYMBOL(kmemleak_free_part_phys
);
1148 * kmemleak_not_leak_phys - similar to kmemleak_not_leak but taking a physical
1150 * @phys: physical address of the object
1152 void __ref
kmemleak_not_leak_phys(phys_addr_t phys
)
1154 if (PHYS_PFN(phys
) >= min_low_pfn
&& PHYS_PFN(phys
) < max_low_pfn
)
1155 kmemleak_not_leak(__va(phys
));
1157 EXPORT_SYMBOL(kmemleak_not_leak_phys
);
1160 * kmemleak_ignore_phys - similar to kmemleak_ignore but taking a physical
1162 * @phys: physical address of the object
1164 void __ref
kmemleak_ignore_phys(phys_addr_t phys
)
1166 if (PHYS_PFN(phys
) >= min_low_pfn
&& PHYS_PFN(phys
) < max_low_pfn
)
1167 kmemleak_ignore(__va(phys
));
1169 EXPORT_SYMBOL(kmemleak_ignore_phys
);
1172 * Update an object's checksum and return true if it was modified.
1174 static bool update_checksum(struct kmemleak_object
*object
)
1176 u32 old_csum
= object
->checksum
;
1178 kasan_disable_current();
1179 kcsan_disable_current();
1180 object
->checksum
= crc32(0, kasan_reset_tag((void *)object
->pointer
), object
->size
);
1181 kasan_enable_current();
1182 kcsan_enable_current();
1184 return object
->checksum
!= old_csum
;
1188 * Update an object's references. object->lock must be held by the caller.
1190 static void update_refs(struct kmemleak_object
*object
)
1192 if (!color_white(object
)) {
1193 /* non-orphan, ignored or new */
1198 * Increase the object's reference count (number of pointers to the
1199 * memory block). If this count reaches the required minimum, the
1200 * object's color will become gray and it will be added to the
1204 if (color_gray(object
)) {
1205 /* put_object() called when removing from gray_list */
1206 WARN_ON(!get_object(object
));
1207 list_add_tail(&object
->gray_list
, &gray_list
);
1212 * Memory scanning is a long process and it needs to be interruptible. This
1213 * function checks whether such interrupt condition occurred.
1215 static int scan_should_stop(void)
1217 if (!kmemleak_enabled
)
1221 * This function may be called from either process or kthread context,
1222 * hence the need to check for both stop conditions.
1225 return signal_pending(current
);
1227 return kthread_should_stop();
1233 * Scan a memory block (exclusive range) for valid pointers and add those
1234 * found to the gray list.
1236 static void scan_block(void *_start
, void *_end
,
1237 struct kmemleak_object
*scanned
)
1240 unsigned long *start
= PTR_ALIGN(_start
, BYTES_PER_POINTER
);
1241 unsigned long *end
= _end
- (BYTES_PER_POINTER
- 1);
1242 unsigned long flags
;
1243 unsigned long untagged_ptr
;
1245 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
1246 for (ptr
= start
; ptr
< end
; ptr
++) {
1247 struct kmemleak_object
*object
;
1248 unsigned long pointer
;
1249 unsigned long excess_ref
;
1251 if (scan_should_stop())
1254 kasan_disable_current();
1255 pointer
= *(unsigned long *)kasan_reset_tag((void *)ptr
);
1256 kasan_enable_current();
1258 untagged_ptr
= (unsigned long)kasan_reset_tag((void *)pointer
);
1259 if (untagged_ptr
< min_addr
|| untagged_ptr
>= max_addr
)
1263 * No need for get_object() here since we hold kmemleak_lock.
1264 * object->use_count cannot be dropped to 0 while the object
1265 * is still present in object_tree_root and object_list
1266 * (with updates protected by kmemleak_lock).
1268 object
= lookup_object(pointer
, 1);
1271 if (object
== scanned
)
1272 /* self referenced, ignore */
1276 * Avoid the lockdep recursive warning on object->lock being
1277 * previously acquired in scan_object(). These locks are
1278 * enclosed by scan_mutex.
1280 raw_spin_lock_nested(&object
->lock
, SINGLE_DEPTH_NESTING
);
1281 /* only pass surplus references (object already gray) */
1282 if (color_gray(object
)) {
1283 excess_ref
= object
->excess_ref
;
1284 /* no need for update_refs() if object already gray */
1287 update_refs(object
);
1289 raw_spin_unlock(&object
->lock
);
1292 object
= lookup_object(excess_ref
, 0);
1295 if (object
== scanned
)
1296 /* circular reference, ignore */
1298 raw_spin_lock_nested(&object
->lock
, SINGLE_DEPTH_NESTING
);
1299 update_refs(object
);
1300 raw_spin_unlock(&object
->lock
);
1303 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
1307 * Scan a large memory block in MAX_SCAN_SIZE chunks to reduce the latency.
1310 static void scan_large_block(void *start
, void *end
)
1314 while (start
< end
) {
1315 next
= min(start
+ MAX_SCAN_SIZE
, end
);
1316 scan_block(start
, next
, NULL
);
1324 * Scan a memory block corresponding to a kmemleak_object. A condition is
1325 * that object->use_count >= 1.
1327 static void scan_object(struct kmemleak_object
*object
)
1329 struct kmemleak_scan_area
*area
;
1330 unsigned long flags
;
1333 * Once the object->lock is acquired, the corresponding memory block
1334 * cannot be freed (the same lock is acquired in delete_object).
1336 raw_spin_lock_irqsave(&object
->lock
, flags
);
1337 if (object
->flags
& OBJECT_NO_SCAN
)
1339 if (!(object
->flags
& OBJECT_ALLOCATED
))
1340 /* already freed object */
1342 if (hlist_empty(&object
->area_list
) ||
1343 object
->flags
& OBJECT_FULL_SCAN
) {
1344 void *start
= (void *)object
->pointer
;
1345 void *end
= (void *)(object
->pointer
+ object
->size
);
1349 next
= min(start
+ MAX_SCAN_SIZE
, end
);
1350 scan_block(start
, next
, object
);
1356 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1358 raw_spin_lock_irqsave(&object
->lock
, flags
);
1359 } while (object
->flags
& OBJECT_ALLOCATED
);
1361 hlist_for_each_entry(area
, &object
->area_list
, node
)
1362 scan_block((void *)area
->start
,
1363 (void *)(area
->start
+ area
->size
),
1366 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1370 * Scan the objects already referenced (gray objects). More objects will be
1371 * referenced and, if there are no memory leaks, all the objects are scanned.
1373 static void scan_gray_list(void)
1375 struct kmemleak_object
*object
, *tmp
;
1378 * The list traversal is safe for both tail additions and removals
1379 * from inside the loop. The kmemleak objects cannot be freed from
1380 * outside the loop because their use_count was incremented.
1382 object
= list_entry(gray_list
.next
, typeof(*object
), gray_list
);
1383 while (&object
->gray_list
!= &gray_list
) {
1386 /* may add new objects to the list */
1387 if (!scan_should_stop())
1388 scan_object(object
);
1390 tmp
= list_entry(object
->gray_list
.next
, typeof(*object
),
1393 /* remove the object from the list and release it */
1394 list_del(&object
->gray_list
);
1399 WARN_ON(!list_empty(&gray_list
));
1403 * Scan data sections and all the referenced memory blocks allocated via the
1404 * kernel's standard allocators. This function must be called with the
1407 static void kmemleak_scan(void)
1409 unsigned long flags
;
1410 struct kmemleak_object
*object
;
1412 int __maybe_unused i
;
1415 jiffies_last_scan
= jiffies
;
1417 /* prepare the kmemleak_object's */
1419 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1420 raw_spin_lock_irqsave(&object
->lock
, flags
);
1423 * With a few exceptions there should be a maximum of
1424 * 1 reference to any object at this point.
1426 if (atomic_read(&object
->use_count
) > 1) {
1427 pr_debug("object->use_count = %d\n",
1428 atomic_read(&object
->use_count
));
1429 dump_object_info(object
);
1432 /* reset the reference count (whiten the object) */
1434 if (color_gray(object
) && get_object(object
))
1435 list_add_tail(&object
->gray_list
, &gray_list
);
1437 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1442 /* per-cpu sections scanning */
1443 for_each_possible_cpu(i
)
1444 scan_large_block(__per_cpu_start
+ per_cpu_offset(i
),
1445 __per_cpu_end
+ per_cpu_offset(i
));
1449 * Struct page scanning for each node.
1452 for_each_populated_zone(zone
) {
1453 unsigned long start_pfn
= zone
->zone_start_pfn
;
1454 unsigned long end_pfn
= zone_end_pfn(zone
);
1457 for (pfn
= start_pfn
; pfn
< end_pfn
; pfn
++) {
1458 struct page
*page
= pfn_to_online_page(pfn
);
1463 /* only scan pages belonging to this zone */
1464 if (page_zone(page
) != zone
)
1466 /* only scan if page is in use */
1467 if (page_count(page
) == 0)
1469 scan_block(page
, page
+ 1, NULL
);
1477 * Scanning the task stacks (may introduce false negatives).
1479 if (kmemleak_stack_scan
) {
1480 struct task_struct
*p
, *g
;
1483 for_each_process_thread(g
, p
) {
1484 void *stack
= try_get_task_stack(p
);
1486 scan_block(stack
, stack
+ THREAD_SIZE
, NULL
);
1494 * Scan the objects already referenced from the sections scanned
1500 * Check for new or unreferenced objects modified since the previous
1501 * scan and color them gray until the next scan.
1504 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1505 raw_spin_lock_irqsave(&object
->lock
, flags
);
1506 if (color_white(object
) && (object
->flags
& OBJECT_ALLOCATED
)
1507 && update_checksum(object
) && get_object(object
)) {
1508 /* color it gray temporarily */
1509 object
->count
= object
->min_count
;
1510 list_add_tail(&object
->gray_list
, &gray_list
);
1512 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1517 * Re-scan the gray list for modified unreferenced objects.
1522 * If scanning was stopped do not report any new unreferenced objects.
1524 if (scan_should_stop())
1528 * Scanning result reporting.
1531 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1532 raw_spin_lock_irqsave(&object
->lock
, flags
);
1533 if (unreferenced_object(object
) &&
1534 !(object
->flags
& OBJECT_REPORTED
)) {
1535 object
->flags
|= OBJECT_REPORTED
;
1537 if (kmemleak_verbose
)
1538 print_unreferenced(NULL
, object
);
1542 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1547 kmemleak_found_leaks
= true;
1549 pr_info("%d new suspected memory leaks (see /sys/kernel/debug/kmemleak)\n",
1556 * Thread function performing automatic memory scanning. Unreferenced objects
1557 * at the end of a memory scan are reported but only the first time.
1559 static int kmemleak_scan_thread(void *arg
)
1561 static int first_run
= IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN
);
1563 pr_info("Automatic memory scanning thread started\n");
1564 set_user_nice(current
, 10);
1567 * Wait before the first scan to allow the system to fully initialize.
1570 signed long timeout
= msecs_to_jiffies(SECS_FIRST_SCAN
* 1000);
1572 while (timeout
&& !kthread_should_stop())
1573 timeout
= schedule_timeout_interruptible(timeout
);
1576 while (!kthread_should_stop()) {
1577 signed long timeout
= READ_ONCE(jiffies_scan_wait
);
1579 mutex_lock(&scan_mutex
);
1581 mutex_unlock(&scan_mutex
);
1583 /* wait before the next scan */
1584 while (timeout
&& !kthread_should_stop())
1585 timeout
= schedule_timeout_interruptible(timeout
);
1588 pr_info("Automatic memory scanning thread ended\n");
1594 * Start the automatic memory scanning thread. This function must be called
1595 * with the scan_mutex held.
1597 static void start_scan_thread(void)
1601 scan_thread
= kthread_run(kmemleak_scan_thread
, NULL
, "kmemleak");
1602 if (IS_ERR(scan_thread
)) {
1603 pr_warn("Failed to create the scan thread\n");
1609 * Stop the automatic memory scanning thread.
1611 static void stop_scan_thread(void)
1614 kthread_stop(scan_thread
);
1620 * Iterate over the object_list and return the first valid object at or after
1621 * the required position with its use_count incremented. The function triggers
1622 * a memory scanning when the pos argument points to the first position.
1624 static void *kmemleak_seq_start(struct seq_file
*seq
, loff_t
*pos
)
1626 struct kmemleak_object
*object
;
1630 err
= mutex_lock_interruptible(&scan_mutex
);
1632 return ERR_PTR(err
);
1635 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1638 if (get_object(object
))
1647 * Return the next object in the object_list. The function decrements the
1648 * use_count of the previous object and increases that of the next one.
1650 static void *kmemleak_seq_next(struct seq_file
*seq
, void *v
, loff_t
*pos
)
1652 struct kmemleak_object
*prev_obj
= v
;
1653 struct kmemleak_object
*next_obj
= NULL
;
1654 struct kmemleak_object
*obj
= prev_obj
;
1658 list_for_each_entry_continue_rcu(obj
, &object_list
, object_list
) {
1659 if (get_object(obj
)) {
1665 put_object(prev_obj
);
1670 * Decrement the use_count of the last object required, if any.
1672 static void kmemleak_seq_stop(struct seq_file
*seq
, void *v
)
1676 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1677 * waiting was interrupted, so only release it if !IS_ERR.
1680 mutex_unlock(&scan_mutex
);
1687 * Print the information for an unreferenced object to the seq file.
1689 static int kmemleak_seq_show(struct seq_file
*seq
, void *v
)
1691 struct kmemleak_object
*object
= v
;
1692 unsigned long flags
;
1694 raw_spin_lock_irqsave(&object
->lock
, flags
);
1695 if ((object
->flags
& OBJECT_REPORTED
) && unreferenced_object(object
))
1696 print_unreferenced(seq
, object
);
1697 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1701 static const struct seq_operations kmemleak_seq_ops
= {
1702 .start
= kmemleak_seq_start
,
1703 .next
= kmemleak_seq_next
,
1704 .stop
= kmemleak_seq_stop
,
1705 .show
= kmemleak_seq_show
,
1708 static int kmemleak_open(struct inode
*inode
, struct file
*file
)
1710 return seq_open(file
, &kmemleak_seq_ops
);
1713 static int dump_str_object_info(const char *str
)
1715 unsigned long flags
;
1716 struct kmemleak_object
*object
;
1719 if (kstrtoul(str
, 0, &addr
))
1721 object
= find_and_get_object(addr
, 0);
1723 pr_info("Unknown object at 0x%08lx\n", addr
);
1727 raw_spin_lock_irqsave(&object
->lock
, flags
);
1728 dump_object_info(object
);
1729 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1736 * We use grey instead of black to ensure we can do future scans on the same
1737 * objects. If we did not do future scans these black objects could
1738 * potentially contain references to newly allocated objects in the future and
1739 * we'd end up with false positives.
1741 static void kmemleak_clear(void)
1743 struct kmemleak_object
*object
;
1744 unsigned long flags
;
1747 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1748 raw_spin_lock_irqsave(&object
->lock
, flags
);
1749 if ((object
->flags
& OBJECT_REPORTED
) &&
1750 unreferenced_object(object
))
1751 __paint_it(object
, KMEMLEAK_GREY
);
1752 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1756 kmemleak_found_leaks
= false;
1759 static void __kmemleak_do_cleanup(void);
1762 * File write operation to configure kmemleak at run-time. The following
1763 * commands can be written to the /sys/kernel/debug/kmemleak file:
1764 * off - disable kmemleak (irreversible)
1765 * stack=on - enable the task stacks scanning
1766 * stack=off - disable the tasks stacks scanning
1767 * scan=on - start the automatic memory scanning thread
1768 * scan=off - stop the automatic memory scanning thread
1769 * scan=... - set the automatic memory scanning period in seconds (0 to
1771 * scan - trigger a memory scan
1772 * clear - mark all current reported unreferenced kmemleak objects as
1773 * grey to ignore printing them, or free all kmemleak objects
1774 * if kmemleak has been disabled.
1775 * dump=... - dump information about the object found at the given address
1777 static ssize_t
kmemleak_write(struct file
*file
, const char __user
*user_buf
,
1778 size_t size
, loff_t
*ppos
)
1784 buf_size
= min(size
, (sizeof(buf
) - 1));
1785 if (strncpy_from_user(buf
, user_buf
, buf_size
) < 0)
1789 ret
= mutex_lock_interruptible(&scan_mutex
);
1793 if (strncmp(buf
, "clear", 5) == 0) {
1794 if (kmemleak_enabled
)
1797 __kmemleak_do_cleanup();
1801 if (!kmemleak_enabled
) {
1806 if (strncmp(buf
, "off", 3) == 0)
1808 else if (strncmp(buf
, "stack=on", 8) == 0)
1809 kmemleak_stack_scan
= 1;
1810 else if (strncmp(buf
, "stack=off", 9) == 0)
1811 kmemleak_stack_scan
= 0;
1812 else if (strncmp(buf
, "scan=on", 7) == 0)
1813 start_scan_thread();
1814 else if (strncmp(buf
, "scan=off", 8) == 0)
1816 else if (strncmp(buf
, "scan=", 5) == 0) {
1818 unsigned long msecs
;
1820 ret
= kstrtouint(buf
+ 5, 0, &secs
);
1824 msecs
= secs
* MSEC_PER_SEC
;
1825 if (msecs
> UINT_MAX
)
1830 WRITE_ONCE(jiffies_scan_wait
, msecs_to_jiffies(msecs
));
1831 start_scan_thread();
1833 } else if (strncmp(buf
, "scan", 4) == 0)
1835 else if (strncmp(buf
, "dump=", 5) == 0)
1836 ret
= dump_str_object_info(buf
+ 5);
1841 mutex_unlock(&scan_mutex
);
1845 /* ignore the rest of the buffer, only one command at a time */
1850 static const struct file_operations kmemleak_fops
= {
1851 .owner
= THIS_MODULE
,
1852 .open
= kmemleak_open
,
1854 .write
= kmemleak_write
,
1855 .llseek
= seq_lseek
,
1856 .release
= seq_release
,
1859 static void __kmemleak_do_cleanup(void)
1861 struct kmemleak_object
*object
, *tmp
;
1864 * Kmemleak has already been disabled, no need for RCU list traversal
1865 * or kmemleak_lock held.
1867 list_for_each_entry_safe(object
, tmp
, &object_list
, object_list
) {
1868 __remove_object(object
);
1869 __delete_object(object
);
1874 * Stop the memory scanning thread and free the kmemleak internal objects if
1875 * no previous scan thread (otherwise, kmemleak may still have some useful
1876 * information on memory leaks).
1878 static void kmemleak_do_cleanup(struct work_struct
*work
)
1882 mutex_lock(&scan_mutex
);
1884 * Once it is made sure that kmemleak_scan has stopped, it is safe to no
1885 * longer track object freeing. Ordering of the scan thread stopping and
1886 * the memory accesses below is guaranteed by the kthread_stop()
1889 kmemleak_free_enabled
= 0;
1890 mutex_unlock(&scan_mutex
);
1892 if (!kmemleak_found_leaks
)
1893 __kmemleak_do_cleanup();
1895 pr_info("Kmemleak disabled without freeing internal data. Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\".\n");
1898 static DECLARE_WORK(cleanup_work
, kmemleak_do_cleanup
);
1901 * Disable kmemleak. No memory allocation/freeing will be traced once this
1902 * function is called. Disabling kmemleak is an irreversible operation.
1904 static void kmemleak_disable(void)
1906 /* atomically check whether it was already invoked */
1907 if (cmpxchg(&kmemleak_error
, 0, 1))
1910 /* stop any memory operation tracing */
1911 kmemleak_enabled
= 0;
1913 /* check whether it is too early for a kernel thread */
1914 if (kmemleak_initialized
)
1915 schedule_work(&cleanup_work
);
1917 kmemleak_free_enabled
= 0;
1919 pr_info("Kernel memory leak detector disabled\n");
1923 * Allow boot-time kmemleak disabling (enabled by default).
1925 static int __init
kmemleak_boot_config(char *str
)
1929 if (strcmp(str
, "off") == 0)
1931 else if (strcmp(str
, "on") == 0)
1932 kmemleak_skip_disable
= 1;
1937 early_param("kmemleak", kmemleak_boot_config
);
1940 * Kmemleak initialization.
1942 void __init
kmemleak_init(void)
1944 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1945 if (!kmemleak_skip_disable
) {
1954 jiffies_min_age
= msecs_to_jiffies(MSECS_MIN_AGE
);
1955 jiffies_scan_wait
= msecs_to_jiffies(SECS_SCAN_WAIT
* 1000);
1957 object_cache
= KMEM_CACHE(kmemleak_object
, SLAB_NOLEAKTRACE
);
1958 scan_area_cache
= KMEM_CACHE(kmemleak_scan_area
, SLAB_NOLEAKTRACE
);
1960 /* register the data/bss sections */
1961 create_object((unsigned long)_sdata
, _edata
- _sdata
,
1962 KMEMLEAK_GREY
, GFP_ATOMIC
);
1963 create_object((unsigned long)__bss_start
, __bss_stop
- __bss_start
,
1964 KMEMLEAK_GREY
, GFP_ATOMIC
);
1965 /* only register .data..ro_after_init if not within .data */
1966 if (&__start_ro_after_init
< &_sdata
|| &__end_ro_after_init
> &_edata
)
1967 create_object((unsigned long)__start_ro_after_init
,
1968 __end_ro_after_init
- __start_ro_after_init
,
1969 KMEMLEAK_GREY
, GFP_ATOMIC
);
1973 * Late initialization function.
1975 static int __init
kmemleak_late_init(void)
1977 kmemleak_initialized
= 1;
1979 debugfs_create_file("kmemleak", 0644, NULL
, NULL
, &kmemleak_fops
);
1981 if (kmemleak_error
) {
1983 * Some error occurred and kmemleak was disabled. There is a
1984 * small chance that kmemleak_disable() was called immediately
1985 * after setting kmemleak_initialized and we may end up with
1986 * two clean-up threads but serialized by scan_mutex.
1988 schedule_work(&cleanup_work
);
1992 if (IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN
)) {
1993 mutex_lock(&scan_mutex
);
1994 start_scan_thread();
1995 mutex_unlock(&scan_mutex
);
1998 pr_info("Kernel memory leak detector initialized (mem pool available: %d)\n",
1999 mem_pool_free_count
);
2003 late_initcall(kmemleak_late_init
);