4 * Copyright (C) 2008 ARM Limited
5 * Written by Catalin Marinas <catalin.marinas@arm.com>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 * For more information on the algorithm and kmemleak usage, please see
22 * Documentation/kmemleak.txt.
27 * The following locks and mutexes are used by kmemleak:
29 * - kmemleak_lock (rwlock): protects the object_list modifications and
30 * accesses to the object_tree_root. The object_list is the main list
31 * holding the metadata (struct kmemleak_object) for the allocated memory
32 * blocks. The object_tree_root is a red black tree used to look-up
33 * metadata based on a pointer to the corresponding memory block. The
34 * kmemleak_object structures are added to the object_list and
35 * object_tree_root in the create_object() function called from the
36 * kmemleak_alloc() callback and removed in delete_object() called from the
37 * kmemleak_free() callback
38 * - kmemleak_object.lock (spinlock): protects a kmemleak_object. Accesses to
39 * the metadata (e.g. count) are protected by this lock. Note that some
40 * members of this structure may be protected by other means (atomic or
41 * kmemleak_lock). This lock is also held when scanning the corresponding
42 * memory block to avoid the kernel freeing it via the kmemleak_free()
43 * callback. This is less heavyweight than holding a global lock like
44 * kmemleak_lock during scanning
45 * - scan_mutex (mutex): ensures that only one thread may scan the memory for
46 * unreferenced objects at a time. The gray_list contains the objects which
47 * are already referenced or marked as false positives and need to be
48 * scanned. This list is only modified during a scanning episode when the
49 * scan_mutex is held. At the end of a scan, the gray_list is always empty.
50 * Note that the kmemleak_object.use_count is incremented when an object is
51 * added to the gray_list and therefore cannot be freed. This mutex also
52 * prevents multiple users of the "kmemleak" debugfs file together with
53 * modifications to the memory scanning parameters including the scan_thread
56 * The kmemleak_object structures have a use_count incremented or decremented
57 * using the get_object()/put_object() functions. When the use_count becomes
58 * 0, this count can no longer be incremented and put_object() schedules the
59 * kmemleak_object freeing via an RCU callback. All calls to the get_object()
60 * function must be protected by rcu_read_lock() to avoid accessing a freed
64 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
66 #include <linux/init.h>
67 #include <linux/kernel.h>
68 #include <linux/list.h>
69 #include <linux/sched.h>
70 #include <linux/jiffies.h>
71 #include <linux/delay.h>
72 #include <linux/export.h>
73 #include <linux/kthread.h>
74 #include <linux/rbtree.h>
76 #include <linux/debugfs.h>
77 #include <linux/seq_file.h>
78 #include <linux/cpumask.h>
79 #include <linux/spinlock.h>
80 #include <linux/mutex.h>
81 #include <linux/rcupdate.h>
82 #include <linux/stacktrace.h>
83 #include <linux/cache.h>
84 #include <linux/percpu.h>
85 #include <linux/hardirq.h>
86 #include <linux/mmzone.h>
87 #include <linux/slab.h>
88 #include <linux/thread_info.h>
89 #include <linux/err.h>
90 #include <linux/uaccess.h>
91 #include <linux/string.h>
92 #include <linux/nodemask.h>
94 #include <linux/workqueue.h>
95 #include <linux/crc32.h>
97 #include <asm/sections.h>
98 #include <asm/processor.h>
99 #include <linux/atomic.h>
101 #include <linux/kmemcheck.h>
102 #include <linux/kmemleak.h>
103 #include <linux/memory_hotplug.h>
106 * Kmemleak configuration and common defines.
108 #define MAX_TRACE 16 /* stack trace length */
109 #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
110 #define SECS_FIRST_SCAN 60 /* delay before the first scan */
111 #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
112 #define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
114 #define BYTES_PER_POINTER sizeof(void *)
116 /* GFP bitmask for kmemleak internal allocations */
117 #define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
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 long 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 /* minimum number of a pointers found before it is considered leak */
152 /* the total number of pointers found pointing to this object */
154 /* checksum for detecting modified objects */
156 /* memory ranges to be scanned inside an object (empty for all) */
157 struct hlist_head area_list
;
158 unsigned long trace
[MAX_TRACE
];
159 unsigned int trace_len
;
160 unsigned long jiffies
; /* creation timestamp */
161 pid_t pid
; /* pid of the current task */
162 char comm
[TASK_COMM_LEN
]; /* executable name */
165 /* flag representing the memory block allocation status */
166 #define OBJECT_ALLOCATED (1 << 0)
167 /* flag set after the first reporting of an unreference object */
168 #define OBJECT_REPORTED (1 << 1)
169 /* flag set to not scan the object */
170 #define OBJECT_NO_SCAN (1 << 2)
172 /* number of bytes to print per line; must be 16 or 32 */
173 #define HEX_ROW_SIZE 16
174 /* number of bytes to print at a time (1, 2, 4, 8) */
175 #define HEX_GROUP_SIZE 1
176 /* include ASCII after the hex output */
178 /* max number of lines to be printed */
179 #define HEX_MAX_LINES 2
181 /* the list of all allocated objects */
182 static LIST_HEAD(object_list
);
183 /* the list of gray-colored objects (see color_gray comment below) */
184 static LIST_HEAD(gray_list
);
185 /* search tree for object boundaries */
186 static struct rb_root object_tree_root
= RB_ROOT
;
187 /* rw_lock protecting the access to object_list and object_tree_root */
188 static DEFINE_RWLOCK(kmemleak_lock
);
190 /* allocation caches for kmemleak internal data */
191 static struct kmem_cache
*object_cache
;
192 static struct kmem_cache
*scan_area_cache
;
194 /* set if tracing memory operations is enabled */
195 static int kmemleak_enabled
;
196 /* set in the late_initcall if there were no errors */
197 static int kmemleak_initialized
;
198 /* enables or disables early logging of the memory operations */
199 static int kmemleak_early_log
= 1;
200 /* set if a kmemleak warning was issued */
201 static int kmemleak_warning
;
202 /* set if a fatal kmemleak error has occurred */
203 static int kmemleak_error
;
205 /* minimum and maximum address that may be valid pointers */
206 static unsigned long min_addr
= ULONG_MAX
;
207 static unsigned long max_addr
;
209 static struct task_struct
*scan_thread
;
210 /* used to avoid reporting of recently allocated objects */
211 static unsigned long jiffies_min_age
;
212 static unsigned long jiffies_last_scan
;
213 /* delay between automatic memory scannings */
214 static signed long jiffies_scan_wait
;
215 /* enables or disables the task stacks scanning */
216 static int kmemleak_stack_scan
= 1;
217 /* protects the memory scanning, parameters and debug/kmemleak file access */
218 static DEFINE_MUTEX(scan_mutex
);
219 /* setting kmemleak=on, will set this var, skipping the disable */
220 static int kmemleak_skip_disable
;
221 /* If there are leaks that can be reported */
222 static bool kmemleak_found_leaks
;
225 * Early object allocation/freeing logging. Kmemleak is initialized after the
226 * kernel allocator. However, both the kernel allocator and kmemleak may
227 * allocate memory blocks which need to be tracked. Kmemleak defines an
228 * arbitrary buffer to hold the allocation/freeing information before it is
232 /* kmemleak operation type for early logging */
235 KMEMLEAK_ALLOC_PERCPU
,
238 KMEMLEAK_FREE_PERCPU
,
246 * Structure holding the information passed to kmemleak callbacks during the
250 int op_type
; /* kmemleak operation type */
251 const void *ptr
; /* allocated/freed memory block */
252 size_t size
; /* memory block size */
253 int min_count
; /* minimum reference count */
254 unsigned long trace
[MAX_TRACE
]; /* stack trace */
255 unsigned int trace_len
; /* stack trace length */
258 /* early logging buffer and current position */
259 static struct early_log
260 early_log
[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE
] __initdata
;
261 static int crt_early_log __initdata
;
263 static void kmemleak_disable(void);
266 * Print a warning and dump the stack trace.
268 #define kmemleak_warn(x...) do { \
271 kmemleak_warning = 1; \
275 * Macro invoked when a serious kmemleak condition occurred and cannot be
276 * recovered from. Kmemleak will be disabled and further allocation/freeing
277 * tracing no longer available.
279 #define kmemleak_stop(x...) do { \
281 kmemleak_disable(); \
285 * Printing of the objects hex dump to the seq file. The number of lines to be
286 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
287 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
288 * with the object->lock held.
290 static void hex_dump_object(struct seq_file
*seq
,
291 struct kmemleak_object
*object
)
293 const u8
*ptr
= (const u8
*)object
->pointer
;
294 int i
, len
, remaining
;
295 unsigned char linebuf
[HEX_ROW_SIZE
* 5];
297 /* limit the number of lines to HEX_MAX_LINES */
299 min(object
->size
, (size_t)(HEX_MAX_LINES
* HEX_ROW_SIZE
));
301 seq_printf(seq
, " hex dump (first %d bytes):\n", len
);
302 for (i
= 0; i
< len
; i
+= HEX_ROW_SIZE
) {
303 int linelen
= min(remaining
, HEX_ROW_SIZE
);
305 remaining
-= HEX_ROW_SIZE
;
306 hex_dump_to_buffer(ptr
+ i
, linelen
, HEX_ROW_SIZE
,
307 HEX_GROUP_SIZE
, linebuf
, sizeof(linebuf
),
309 seq_printf(seq
, " %s\n", linebuf
);
314 * Object colors, encoded with count and min_count:
315 * - white - orphan object, not enough references to it (count < min_count)
316 * - gray - not orphan, not marked as false positive (min_count == 0) or
317 * sufficient references to it (count >= min_count)
318 * - black - ignore, it doesn't contain references (e.g. text section)
319 * (min_count == -1). No function defined for this color.
320 * Newly created objects don't have any color assigned (object->count == -1)
321 * before the next memory scan when they become white.
323 static bool color_white(const struct kmemleak_object
*object
)
325 return object
->count
!= KMEMLEAK_BLACK
&&
326 object
->count
< object
->min_count
;
329 static bool color_gray(const struct kmemleak_object
*object
)
331 return object
->min_count
!= KMEMLEAK_BLACK
&&
332 object
->count
>= object
->min_count
;
336 * Objects are considered unreferenced only if their color is white, they have
337 * not be deleted and have a minimum age to avoid false positives caused by
338 * pointers temporarily stored in CPU registers.
340 static bool unreferenced_object(struct kmemleak_object
*object
)
342 return (color_white(object
) && object
->flags
& OBJECT_ALLOCATED
) &&
343 time_before_eq(object
->jiffies
+ jiffies_min_age
,
348 * Printing of the unreferenced objects information to the seq file. The
349 * print_unreferenced function must be called with the object->lock held.
351 static void print_unreferenced(struct seq_file
*seq
,
352 struct kmemleak_object
*object
)
355 unsigned int msecs_age
= jiffies_to_msecs(jiffies
- object
->jiffies
);
357 seq_printf(seq
, "unreferenced object 0x%08lx (size %zu):\n",
358 object
->pointer
, object
->size
);
359 seq_printf(seq
, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
360 object
->comm
, object
->pid
, object
->jiffies
,
361 msecs_age
/ 1000, msecs_age
% 1000);
362 hex_dump_object(seq
, object
);
363 seq_printf(seq
, " backtrace:\n");
365 for (i
= 0; i
< object
->trace_len
; i
++) {
366 void *ptr
= (void *)object
->trace
[i
];
367 seq_printf(seq
, " [<%p>] %pS\n", ptr
, ptr
);
372 * Print the kmemleak_object information. This function is used mainly for
373 * debugging special cases when kmemleak operations. It must be called with
374 * the object->lock held.
376 static void dump_object_info(struct kmemleak_object
*object
)
378 struct stack_trace trace
;
380 trace
.nr_entries
= object
->trace_len
;
381 trace
.entries
= object
->trace
;
383 pr_notice("Object 0x%08lx (size %zu):\n",
384 object
->pointer
, object
->size
);
385 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
386 object
->comm
, object
->pid
, object
->jiffies
);
387 pr_notice(" min_count = %d\n", object
->min_count
);
388 pr_notice(" count = %d\n", object
->count
);
389 pr_notice(" flags = 0x%lx\n", object
->flags
);
390 pr_notice(" checksum = %d\n", object
->checksum
);
391 pr_notice(" backtrace:\n");
392 print_stack_trace(&trace
, 4);
396 * Look-up a memory block metadata (kmemleak_object) in the object search
397 * tree based on a pointer value. If alias is 0, only values pointing to the
398 * beginning of the memory block are allowed. The kmemleak_lock must be held
399 * when calling this function.
401 static struct kmemleak_object
*lookup_object(unsigned long ptr
, int alias
)
403 struct rb_node
*rb
= object_tree_root
.rb_node
;
406 struct kmemleak_object
*object
=
407 rb_entry(rb
, struct kmemleak_object
, rb_node
);
408 if (ptr
< object
->pointer
)
409 rb
= object
->rb_node
.rb_left
;
410 else if (object
->pointer
+ object
->size
<= ptr
)
411 rb
= object
->rb_node
.rb_right
;
412 else if (object
->pointer
== ptr
|| alias
)
415 kmemleak_warn("Found object by alias at 0x%08lx\n",
417 dump_object_info(object
);
425 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
426 * that once an object's use_count reached 0, the RCU freeing was already
427 * registered and the object should no longer be used. This function must be
428 * called under the protection of rcu_read_lock().
430 static int get_object(struct kmemleak_object
*object
)
432 return atomic_inc_not_zero(&object
->use_count
);
436 * RCU callback to free a kmemleak_object.
438 static void free_object_rcu(struct rcu_head
*rcu
)
440 struct hlist_node
*tmp
;
441 struct kmemleak_scan_area
*area
;
442 struct kmemleak_object
*object
=
443 container_of(rcu
, struct kmemleak_object
, rcu
);
446 * Once use_count is 0 (guaranteed by put_object), there is no other
447 * code accessing this object, hence no need for locking.
449 hlist_for_each_entry_safe(area
, tmp
, &object
->area_list
, node
) {
450 hlist_del(&area
->node
);
451 kmem_cache_free(scan_area_cache
, area
);
453 kmem_cache_free(object_cache
, object
);
457 * Decrement the object use_count. Once the count is 0, free the object using
458 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
459 * delete_object() path, the delayed RCU freeing ensures that there is no
460 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
463 static void put_object(struct kmemleak_object
*object
)
465 if (!atomic_dec_and_test(&object
->use_count
))
468 /* should only get here after delete_object was called */
469 WARN_ON(object
->flags
& OBJECT_ALLOCATED
);
471 call_rcu(&object
->rcu
, free_object_rcu
);
475 * Look up an object in the object search tree and increase its use_count.
477 static struct kmemleak_object
*find_and_get_object(unsigned long ptr
, int alias
)
480 struct kmemleak_object
*object
= NULL
;
483 read_lock_irqsave(&kmemleak_lock
, flags
);
484 if (ptr
>= min_addr
&& ptr
< max_addr
)
485 object
= lookup_object(ptr
, alias
);
486 read_unlock_irqrestore(&kmemleak_lock
, flags
);
488 /* check whether the object is still available */
489 if (object
&& !get_object(object
))
497 * Save stack trace to the given array of MAX_TRACE size.
499 static int __save_stack_trace(unsigned long *trace
)
501 struct stack_trace stack_trace
;
503 stack_trace
.max_entries
= MAX_TRACE
;
504 stack_trace
.nr_entries
= 0;
505 stack_trace
.entries
= trace
;
506 stack_trace
.skip
= 2;
507 save_stack_trace(&stack_trace
);
509 return stack_trace
.nr_entries
;
513 * Create the metadata (struct kmemleak_object) corresponding to an allocated
514 * memory block and add it to the object_list and object_tree_root.
516 static struct kmemleak_object
*create_object(unsigned long ptr
, size_t size
,
517 int min_count
, gfp_t gfp
)
520 struct kmemleak_object
*object
, *parent
;
521 struct rb_node
**link
, *rb_parent
;
523 object
= kmem_cache_alloc(object_cache
, gfp_kmemleak_mask(gfp
));
525 pr_warning("Cannot allocate a kmemleak_object structure\n");
530 INIT_LIST_HEAD(&object
->object_list
);
531 INIT_LIST_HEAD(&object
->gray_list
);
532 INIT_HLIST_HEAD(&object
->area_list
);
533 spin_lock_init(&object
->lock
);
534 atomic_set(&object
->use_count
, 1);
535 object
->flags
= OBJECT_ALLOCATED
;
536 object
->pointer
= ptr
;
538 object
->min_count
= min_count
;
539 object
->count
= 0; /* white color initially */
540 object
->jiffies
= jiffies
;
541 object
->checksum
= 0;
543 /* task information */
546 strncpy(object
->comm
, "hardirq", sizeof(object
->comm
));
547 } else if (in_softirq()) {
549 strncpy(object
->comm
, "softirq", sizeof(object
->comm
));
551 object
->pid
= current
->pid
;
553 * There is a small chance of a race with set_task_comm(),
554 * however using get_task_comm() here may cause locking
555 * dependency issues with current->alloc_lock. In the worst
556 * case, the command line is not correct.
558 strncpy(object
->comm
, current
->comm
, sizeof(object
->comm
));
561 /* kernel backtrace */
562 object
->trace_len
= __save_stack_trace(object
->trace
);
564 write_lock_irqsave(&kmemleak_lock
, flags
);
566 min_addr
= min(min_addr
, ptr
);
567 max_addr
= max(max_addr
, ptr
+ size
);
568 link
= &object_tree_root
.rb_node
;
572 parent
= rb_entry(rb_parent
, struct kmemleak_object
, rb_node
);
573 if (ptr
+ size
<= parent
->pointer
)
574 link
= &parent
->rb_node
.rb_left
;
575 else if (parent
->pointer
+ parent
->size
<= ptr
)
576 link
= &parent
->rb_node
.rb_right
;
578 kmemleak_stop("Cannot insert 0x%lx into the object "
579 "search tree (overlaps existing)\n",
581 kmem_cache_free(object_cache
, object
);
583 spin_lock(&object
->lock
);
584 dump_object_info(object
);
585 spin_unlock(&object
->lock
);
589 rb_link_node(&object
->rb_node
, rb_parent
, link
);
590 rb_insert_color(&object
->rb_node
, &object_tree_root
);
592 list_add_tail_rcu(&object
->object_list
, &object_list
);
594 write_unlock_irqrestore(&kmemleak_lock
, flags
);
599 * Remove the metadata (struct kmemleak_object) for a memory block from the
600 * object_list and object_tree_root and decrement its use_count.
602 static void __delete_object(struct kmemleak_object
*object
)
606 write_lock_irqsave(&kmemleak_lock
, flags
);
607 rb_erase(&object
->rb_node
, &object_tree_root
);
608 list_del_rcu(&object
->object_list
);
609 write_unlock_irqrestore(&kmemleak_lock
, flags
);
611 WARN_ON(!(object
->flags
& OBJECT_ALLOCATED
));
612 WARN_ON(atomic_read(&object
->use_count
) < 2);
615 * Locking here also ensures that the corresponding memory block
616 * cannot be freed when it is being scanned.
618 spin_lock_irqsave(&object
->lock
, flags
);
619 object
->flags
&= ~OBJECT_ALLOCATED
;
620 spin_unlock_irqrestore(&object
->lock
, flags
);
625 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
628 static void delete_object_full(unsigned long ptr
)
630 struct kmemleak_object
*object
;
632 object
= find_and_get_object(ptr
, 0);
635 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
640 __delete_object(object
);
645 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
646 * delete it. If the memory block is partially freed, the function may create
647 * additional metadata for the remaining parts of the block.
649 static void delete_object_part(unsigned long ptr
, size_t size
)
651 struct kmemleak_object
*object
;
652 unsigned long start
, end
;
654 object
= find_and_get_object(ptr
, 1);
657 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
658 "(size %zu)\n", ptr
, size
);
662 __delete_object(object
);
665 * Create one or two objects that may result from the memory block
666 * split. Note that partial freeing is only done by free_bootmem() and
667 * this happens before kmemleak_init() is called. The path below is
668 * only executed during early log recording in kmemleak_init(), so
669 * GFP_KERNEL is enough.
671 start
= object
->pointer
;
672 end
= object
->pointer
+ object
->size
;
674 create_object(start
, ptr
- start
, object
->min_count
,
676 if (ptr
+ size
< end
)
677 create_object(ptr
+ size
, end
- ptr
- size
, object
->min_count
,
683 static void __paint_it(struct kmemleak_object
*object
, int color
)
685 object
->min_count
= color
;
686 if (color
== KMEMLEAK_BLACK
)
687 object
->flags
|= OBJECT_NO_SCAN
;
690 static void paint_it(struct kmemleak_object
*object
, int color
)
694 spin_lock_irqsave(&object
->lock
, flags
);
695 __paint_it(object
, color
);
696 spin_unlock_irqrestore(&object
->lock
, flags
);
699 static void paint_ptr(unsigned long ptr
, int color
)
701 struct kmemleak_object
*object
;
703 object
= find_and_get_object(ptr
, 0);
705 kmemleak_warn("Trying to color unknown object "
706 "at 0x%08lx as %s\n", ptr
,
707 (color
== KMEMLEAK_GREY
) ? "Grey" :
708 (color
== KMEMLEAK_BLACK
) ? "Black" : "Unknown");
711 paint_it(object
, color
);
716 * Mark an object permanently as gray-colored so that it can no longer be
717 * reported as a leak. This is used in general to mark a false positive.
719 static void make_gray_object(unsigned long ptr
)
721 paint_ptr(ptr
, KMEMLEAK_GREY
);
725 * Mark the object as black-colored so that it is ignored from scans and
728 static void make_black_object(unsigned long ptr
)
730 paint_ptr(ptr
, KMEMLEAK_BLACK
);
734 * Add a scanning area to the object. If at least one such area is added,
735 * kmemleak will only scan these ranges rather than the whole memory block.
737 static void add_scan_area(unsigned long ptr
, size_t size
, gfp_t gfp
)
740 struct kmemleak_object
*object
;
741 struct kmemleak_scan_area
*area
;
743 object
= find_and_get_object(ptr
, 1);
745 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
750 area
= kmem_cache_alloc(scan_area_cache
, gfp_kmemleak_mask(gfp
));
752 pr_warning("Cannot allocate a scan area\n");
756 spin_lock_irqsave(&object
->lock
, flags
);
757 if (size
== SIZE_MAX
) {
758 size
= object
->pointer
+ object
->size
- ptr
;
759 } else if (ptr
+ size
> object
->pointer
+ object
->size
) {
760 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr
);
761 dump_object_info(object
);
762 kmem_cache_free(scan_area_cache
, area
);
766 INIT_HLIST_NODE(&area
->node
);
770 hlist_add_head(&area
->node
, &object
->area_list
);
772 spin_unlock_irqrestore(&object
->lock
, flags
);
778 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
779 * pointer. Such object will not be scanned by kmemleak but references to it
782 static void object_no_scan(unsigned long ptr
)
785 struct kmemleak_object
*object
;
787 object
= find_and_get_object(ptr
, 0);
789 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr
);
793 spin_lock_irqsave(&object
->lock
, flags
);
794 object
->flags
|= OBJECT_NO_SCAN
;
795 spin_unlock_irqrestore(&object
->lock
, flags
);
800 * Log an early kmemleak_* call to the early_log buffer. These calls will be
801 * processed later once kmemleak is fully initialized.
803 static void __init
log_early(int op_type
, const void *ptr
, size_t size
,
807 struct early_log
*log
;
809 if (kmemleak_error
) {
810 /* kmemleak stopped recording, just count the requests */
815 if (crt_early_log
>= ARRAY_SIZE(early_log
)) {
821 * There is no need for locking since the kernel is still in UP mode
822 * at this stage. Disabling the IRQs is enough.
824 local_irq_save(flags
);
825 log
= &early_log
[crt_early_log
];
826 log
->op_type
= op_type
;
829 log
->min_count
= min_count
;
830 log
->trace_len
= __save_stack_trace(log
->trace
);
832 local_irq_restore(flags
);
836 * Log an early allocated block and populate the stack trace.
838 static void early_alloc(struct early_log
*log
)
840 struct kmemleak_object
*object
;
844 if (!kmemleak_enabled
|| !log
->ptr
|| IS_ERR(log
->ptr
))
848 * RCU locking needed to ensure object is not freed via put_object().
851 object
= create_object((unsigned long)log
->ptr
, log
->size
,
852 log
->min_count
, GFP_ATOMIC
);
855 spin_lock_irqsave(&object
->lock
, flags
);
856 for (i
= 0; i
< log
->trace_len
; i
++)
857 object
->trace
[i
] = log
->trace
[i
];
858 object
->trace_len
= log
->trace_len
;
859 spin_unlock_irqrestore(&object
->lock
, flags
);
865 * Log an early allocated block and populate the stack trace.
867 static void early_alloc_percpu(struct early_log
*log
)
870 const void __percpu
*ptr
= log
->ptr
;
872 for_each_possible_cpu(cpu
) {
873 log
->ptr
= per_cpu_ptr(ptr
, cpu
);
879 * kmemleak_alloc - register a newly allocated object
880 * @ptr: pointer to beginning of the object
881 * @size: size of the object
882 * @min_count: minimum number of references to this object. If during memory
883 * scanning a number of references less than @min_count is found,
884 * the object is reported as a memory leak. If @min_count is 0,
885 * the object is never reported as a leak. If @min_count is -1,
886 * the object is ignored (not scanned and not reported as a leak)
887 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
889 * This function is called from the kernel allocators when a new object
890 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
892 void __ref
kmemleak_alloc(const void *ptr
, size_t size
, int min_count
,
895 pr_debug("%s(0x%p, %zu, %d)\n", __func__
, ptr
, size
, min_count
);
897 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
898 create_object((unsigned long)ptr
, size
, min_count
, gfp
);
899 else if (kmemleak_early_log
)
900 log_early(KMEMLEAK_ALLOC
, ptr
, size
, min_count
);
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
909 * This function is called from the kernel percpu allocator when a new object
910 * (memory block) is allocated (alloc_percpu). It assumes GFP_KERNEL
913 void __ref
kmemleak_alloc_percpu(const void __percpu
*ptr
, size_t size
)
917 pr_debug("%s(0x%p, %zu)\n", __func__
, ptr
, size
);
920 * Percpu allocations are only scanned and not reported as leaks
921 * (min_count is set to 0).
923 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
924 for_each_possible_cpu(cpu
)
925 create_object((unsigned long)per_cpu_ptr(ptr
, cpu
),
926 size
, 0, GFP_KERNEL
);
927 else if (kmemleak_early_log
)
928 log_early(KMEMLEAK_ALLOC_PERCPU
, ptr
, size
, 0);
930 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu
);
933 * kmemleak_free - unregister a previously registered object
934 * @ptr: pointer to beginning of the object
936 * This function is called from the kernel allocators when an object (memory
937 * block) is freed (kmem_cache_free, kfree, vfree etc.).
939 void __ref
kmemleak_free(const void *ptr
)
941 pr_debug("%s(0x%p)\n", __func__
, ptr
);
943 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
944 delete_object_full((unsigned long)ptr
);
945 else if (kmemleak_early_log
)
946 log_early(KMEMLEAK_FREE
, ptr
, 0, 0);
948 EXPORT_SYMBOL_GPL(kmemleak_free
);
951 * kmemleak_free_part - partially unregister a previously registered object
952 * @ptr: pointer to the beginning or inside the object. This also
953 * represents the start of the range to be freed
954 * @size: size to be unregistered
956 * This function is called when only a part of a memory block is freed
957 * (usually from the bootmem allocator).
959 void __ref
kmemleak_free_part(const void *ptr
, size_t size
)
961 pr_debug("%s(0x%p)\n", __func__
, ptr
);
963 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
964 delete_object_part((unsigned long)ptr
, size
);
965 else if (kmemleak_early_log
)
966 log_early(KMEMLEAK_FREE_PART
, ptr
, size
, 0);
968 EXPORT_SYMBOL_GPL(kmemleak_free_part
);
971 * kmemleak_free_percpu - unregister a previously registered __percpu object
972 * @ptr: __percpu pointer to beginning of the object
974 * This function is called from the kernel percpu allocator when an object
975 * (memory block) is freed (free_percpu).
977 void __ref
kmemleak_free_percpu(const void __percpu
*ptr
)
981 pr_debug("%s(0x%p)\n", __func__
, ptr
);
983 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
984 for_each_possible_cpu(cpu
)
985 delete_object_full((unsigned long)per_cpu_ptr(ptr
,
987 else if (kmemleak_early_log
)
988 log_early(KMEMLEAK_FREE_PERCPU
, ptr
, 0, 0);
990 EXPORT_SYMBOL_GPL(kmemleak_free_percpu
);
993 * kmemleak_not_leak - mark an allocated object as false positive
994 * @ptr: pointer to beginning of the object
996 * Calling this function on an object will cause the memory block to no longer
997 * be reported as leak and always be scanned.
999 void __ref
kmemleak_not_leak(const void *ptr
)
1001 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1003 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1004 make_gray_object((unsigned long)ptr
);
1005 else if (kmemleak_early_log
)
1006 log_early(KMEMLEAK_NOT_LEAK
, ptr
, 0, 0);
1008 EXPORT_SYMBOL(kmemleak_not_leak
);
1011 * kmemleak_ignore - ignore an allocated object
1012 * @ptr: pointer to beginning of the object
1014 * Calling this function on an object will cause the memory block to be
1015 * ignored (not scanned and not reported as a leak). This is usually done when
1016 * it is known that the corresponding block is not a leak and does not contain
1017 * any references to other allocated memory blocks.
1019 void __ref
kmemleak_ignore(const void *ptr
)
1021 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1023 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1024 make_black_object((unsigned long)ptr
);
1025 else if (kmemleak_early_log
)
1026 log_early(KMEMLEAK_IGNORE
, ptr
, 0, 0);
1028 EXPORT_SYMBOL(kmemleak_ignore
);
1031 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1032 * @ptr: pointer to beginning or inside the object. This also
1033 * represents the start of the scan area
1034 * @size: size of the scan area
1035 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1037 * This function is used when it is known that only certain parts of an object
1038 * contain references to other objects. Kmemleak will only scan these areas
1039 * reducing the number false negatives.
1041 void __ref
kmemleak_scan_area(const void *ptr
, size_t size
, gfp_t gfp
)
1043 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1045 if (kmemleak_enabled
&& ptr
&& size
&& !IS_ERR(ptr
))
1046 add_scan_area((unsigned long)ptr
, size
, gfp
);
1047 else if (kmemleak_early_log
)
1048 log_early(KMEMLEAK_SCAN_AREA
, ptr
, size
, 0);
1050 EXPORT_SYMBOL(kmemleak_scan_area
);
1053 * kmemleak_no_scan - do not scan an allocated object
1054 * @ptr: pointer to beginning of the object
1056 * This function notifies kmemleak not to scan the given memory block. Useful
1057 * in situations where it is known that the given object does not contain any
1058 * references to other objects. Kmemleak will not scan such objects reducing
1059 * the number of false negatives.
1061 void __ref
kmemleak_no_scan(const void *ptr
)
1063 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1065 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1066 object_no_scan((unsigned long)ptr
);
1067 else if (kmemleak_early_log
)
1068 log_early(KMEMLEAK_NO_SCAN
, ptr
, 0, 0);
1070 EXPORT_SYMBOL(kmemleak_no_scan
);
1073 * Update an object's checksum and return true if it was modified.
1075 static bool update_checksum(struct kmemleak_object
*object
)
1077 u32 old_csum
= object
->checksum
;
1079 if (!kmemcheck_is_obj_initialized(object
->pointer
, object
->size
))
1082 object
->checksum
= crc32(0, (void *)object
->pointer
, object
->size
);
1083 return object
->checksum
!= old_csum
;
1087 * Memory scanning is a long process and it needs to be interruptable. This
1088 * function checks whether such interrupt condition occurred.
1090 static int scan_should_stop(void)
1092 if (!kmemleak_enabled
)
1096 * This function may be called from either process or kthread context,
1097 * hence the need to check for both stop conditions.
1100 return signal_pending(current
);
1102 return kthread_should_stop();
1108 * Scan a memory block (exclusive range) for valid pointers and add those
1109 * found to the gray list.
1111 static void scan_block(void *_start
, void *_end
,
1112 struct kmemleak_object
*scanned
, int allow_resched
)
1115 unsigned long *start
= PTR_ALIGN(_start
, BYTES_PER_POINTER
);
1116 unsigned long *end
= _end
- (BYTES_PER_POINTER
- 1);
1118 for (ptr
= start
; ptr
< end
; ptr
++) {
1119 struct kmemleak_object
*object
;
1120 unsigned long flags
;
1121 unsigned long pointer
;
1125 if (scan_should_stop())
1128 /* don't scan uninitialized memory */
1129 if (!kmemcheck_is_obj_initialized((unsigned long)ptr
,
1135 object
= find_and_get_object(pointer
, 1);
1138 if (object
== scanned
) {
1139 /* self referenced, ignore */
1145 * Avoid the lockdep recursive warning on object->lock being
1146 * previously acquired in scan_object(). These locks are
1147 * enclosed by scan_mutex.
1149 spin_lock_irqsave_nested(&object
->lock
, flags
,
1150 SINGLE_DEPTH_NESTING
);
1151 if (!color_white(object
)) {
1152 /* non-orphan, ignored or new */
1153 spin_unlock_irqrestore(&object
->lock
, flags
);
1159 * Increase the object's reference count (number of pointers
1160 * to the memory block). If this count reaches the required
1161 * minimum, the object's color will become gray and it will be
1162 * added to the gray_list.
1165 if (color_gray(object
)) {
1166 list_add_tail(&object
->gray_list
, &gray_list
);
1167 spin_unlock_irqrestore(&object
->lock
, flags
);
1171 spin_unlock_irqrestore(&object
->lock
, flags
);
1177 * Scan a memory block corresponding to a kmemleak_object. A condition is
1178 * that object->use_count >= 1.
1180 static void scan_object(struct kmemleak_object
*object
)
1182 struct kmemleak_scan_area
*area
;
1183 unsigned long flags
;
1186 * Once the object->lock is acquired, the corresponding memory block
1187 * cannot be freed (the same lock is acquired in delete_object).
1189 spin_lock_irqsave(&object
->lock
, flags
);
1190 if (object
->flags
& OBJECT_NO_SCAN
)
1192 if (!(object
->flags
& OBJECT_ALLOCATED
))
1193 /* already freed object */
1195 if (hlist_empty(&object
->area_list
)) {
1196 void *start
= (void *)object
->pointer
;
1197 void *end
= (void *)(object
->pointer
+ object
->size
);
1199 while (start
< end
&& (object
->flags
& OBJECT_ALLOCATED
) &&
1200 !(object
->flags
& OBJECT_NO_SCAN
)) {
1201 scan_block(start
, min(start
+ MAX_SCAN_SIZE
, end
),
1203 start
+= MAX_SCAN_SIZE
;
1205 spin_unlock_irqrestore(&object
->lock
, flags
);
1207 spin_lock_irqsave(&object
->lock
, flags
);
1210 hlist_for_each_entry(area
, &object
->area_list
, node
)
1211 scan_block((void *)area
->start
,
1212 (void *)(area
->start
+ area
->size
),
1215 spin_unlock_irqrestore(&object
->lock
, flags
);
1219 * Scan the objects already referenced (gray objects). More objects will be
1220 * referenced and, if there are no memory leaks, all the objects are scanned.
1222 static void scan_gray_list(void)
1224 struct kmemleak_object
*object
, *tmp
;
1227 * The list traversal is safe for both tail additions and removals
1228 * from inside the loop. The kmemleak objects cannot be freed from
1229 * outside the loop because their use_count was incremented.
1231 object
= list_entry(gray_list
.next
, typeof(*object
), gray_list
);
1232 while (&object
->gray_list
!= &gray_list
) {
1235 /* may add new objects to the list */
1236 if (!scan_should_stop())
1237 scan_object(object
);
1239 tmp
= list_entry(object
->gray_list
.next
, typeof(*object
),
1242 /* remove the object from the list and release it */
1243 list_del(&object
->gray_list
);
1248 WARN_ON(!list_empty(&gray_list
));
1252 * Scan data sections and all the referenced memory blocks allocated via the
1253 * kernel's standard allocators. This function must be called with the
1256 static void kmemleak_scan(void)
1258 unsigned long flags
;
1259 struct kmemleak_object
*object
;
1263 jiffies_last_scan
= jiffies
;
1265 /* prepare the kmemleak_object's */
1267 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1268 spin_lock_irqsave(&object
->lock
, flags
);
1271 * With a few exceptions there should be a maximum of
1272 * 1 reference to any object at this point.
1274 if (atomic_read(&object
->use_count
) > 1) {
1275 pr_debug("object->use_count = %d\n",
1276 atomic_read(&object
->use_count
));
1277 dump_object_info(object
);
1280 /* reset the reference count (whiten the object) */
1282 if (color_gray(object
) && get_object(object
))
1283 list_add_tail(&object
->gray_list
, &gray_list
);
1285 spin_unlock_irqrestore(&object
->lock
, flags
);
1289 /* data/bss scanning */
1290 scan_block(_sdata
, _edata
, NULL
, 1);
1291 scan_block(__bss_start
, __bss_stop
, NULL
, 1);
1294 /* per-cpu sections scanning */
1295 for_each_possible_cpu(i
)
1296 scan_block(__per_cpu_start
+ per_cpu_offset(i
),
1297 __per_cpu_end
+ per_cpu_offset(i
), NULL
, 1);
1301 * Struct page scanning for each node.
1303 lock_memory_hotplug();
1304 for_each_online_node(i
) {
1305 unsigned long start_pfn
= node_start_pfn(i
);
1306 unsigned long end_pfn
= node_end_pfn(i
);
1309 for (pfn
= start_pfn
; pfn
< end_pfn
; pfn
++) {
1312 if (!pfn_valid(pfn
))
1314 page
= pfn_to_page(pfn
);
1315 /* only scan if page is in use */
1316 if (page_count(page
) == 0)
1318 scan_block(page
, page
+ 1, NULL
, 1);
1321 unlock_memory_hotplug();
1324 * Scanning the task stacks (may introduce false negatives).
1326 if (kmemleak_stack_scan
) {
1327 struct task_struct
*p
, *g
;
1329 read_lock(&tasklist_lock
);
1330 do_each_thread(g
, p
) {
1331 scan_block(task_stack_page(p
), task_stack_page(p
) +
1332 THREAD_SIZE
, NULL
, 0);
1333 } while_each_thread(g
, p
);
1334 read_unlock(&tasklist_lock
);
1338 * Scan the objects already referenced from the sections scanned
1344 * Check for new or unreferenced objects modified since the previous
1345 * scan and color them gray until the next scan.
1348 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1349 spin_lock_irqsave(&object
->lock
, flags
);
1350 if (color_white(object
) && (object
->flags
& OBJECT_ALLOCATED
)
1351 && update_checksum(object
) && get_object(object
)) {
1352 /* color it gray temporarily */
1353 object
->count
= object
->min_count
;
1354 list_add_tail(&object
->gray_list
, &gray_list
);
1356 spin_unlock_irqrestore(&object
->lock
, flags
);
1361 * Re-scan the gray list for modified unreferenced objects.
1366 * If scanning was stopped do not report any new unreferenced objects.
1368 if (scan_should_stop())
1372 * Scanning result reporting.
1375 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1376 spin_lock_irqsave(&object
->lock
, flags
);
1377 if (unreferenced_object(object
) &&
1378 !(object
->flags
& OBJECT_REPORTED
)) {
1379 object
->flags
|= OBJECT_REPORTED
;
1382 spin_unlock_irqrestore(&object
->lock
, flags
);
1387 kmemleak_found_leaks
= true;
1389 pr_info("%d new suspected memory leaks (see "
1390 "/sys/kernel/debug/kmemleak)\n", new_leaks
);
1396 * Thread function performing automatic memory scanning. Unreferenced objects
1397 * at the end of a memory scan are reported but only the first time.
1399 static int kmemleak_scan_thread(void *arg
)
1401 static int first_run
= 1;
1403 pr_info("Automatic memory scanning thread started\n");
1404 set_user_nice(current
, 10);
1407 * Wait before the first scan to allow the system to fully initialize.
1411 ssleep(SECS_FIRST_SCAN
);
1414 while (!kthread_should_stop()) {
1415 signed long timeout
= jiffies_scan_wait
;
1417 mutex_lock(&scan_mutex
);
1419 mutex_unlock(&scan_mutex
);
1421 /* wait before the next scan */
1422 while (timeout
&& !kthread_should_stop())
1423 timeout
= schedule_timeout_interruptible(timeout
);
1426 pr_info("Automatic memory scanning thread ended\n");
1432 * Start the automatic memory scanning thread. This function must be called
1433 * with the scan_mutex held.
1435 static void start_scan_thread(void)
1439 scan_thread
= kthread_run(kmemleak_scan_thread
, NULL
, "kmemleak");
1440 if (IS_ERR(scan_thread
)) {
1441 pr_warning("Failed to create the scan thread\n");
1447 * Stop the automatic memory scanning thread. This function must be called
1448 * with the scan_mutex held.
1450 static void stop_scan_thread(void)
1453 kthread_stop(scan_thread
);
1459 * Iterate over the object_list and return the first valid object at or after
1460 * the required position with its use_count incremented. The function triggers
1461 * a memory scanning when the pos argument points to the first position.
1463 static void *kmemleak_seq_start(struct seq_file
*seq
, loff_t
*pos
)
1465 struct kmemleak_object
*object
;
1469 err
= mutex_lock_interruptible(&scan_mutex
);
1471 return ERR_PTR(err
);
1474 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1477 if (get_object(object
))
1486 * Return the next object in the object_list. The function decrements the
1487 * use_count of the previous object and increases that of the next one.
1489 static void *kmemleak_seq_next(struct seq_file
*seq
, void *v
, loff_t
*pos
)
1491 struct kmemleak_object
*prev_obj
= v
;
1492 struct kmemleak_object
*next_obj
= NULL
;
1493 struct kmemleak_object
*obj
= prev_obj
;
1497 list_for_each_entry_continue_rcu(obj
, &object_list
, object_list
) {
1498 if (get_object(obj
)) {
1504 put_object(prev_obj
);
1509 * Decrement the use_count of the last object required, if any.
1511 static void kmemleak_seq_stop(struct seq_file
*seq
, void *v
)
1515 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1516 * waiting was interrupted, so only release it if !IS_ERR.
1519 mutex_unlock(&scan_mutex
);
1526 * Print the information for an unreferenced object to the seq file.
1528 static int kmemleak_seq_show(struct seq_file
*seq
, void *v
)
1530 struct kmemleak_object
*object
= v
;
1531 unsigned long flags
;
1533 spin_lock_irqsave(&object
->lock
, flags
);
1534 if ((object
->flags
& OBJECT_REPORTED
) && unreferenced_object(object
))
1535 print_unreferenced(seq
, object
);
1536 spin_unlock_irqrestore(&object
->lock
, flags
);
1540 static const struct seq_operations kmemleak_seq_ops
= {
1541 .start
= kmemleak_seq_start
,
1542 .next
= kmemleak_seq_next
,
1543 .stop
= kmemleak_seq_stop
,
1544 .show
= kmemleak_seq_show
,
1547 static int kmemleak_open(struct inode
*inode
, struct file
*file
)
1549 return seq_open(file
, &kmemleak_seq_ops
);
1552 static int dump_str_object_info(const char *str
)
1554 unsigned long flags
;
1555 struct kmemleak_object
*object
;
1558 if (kstrtoul(str
, 0, &addr
))
1560 object
= find_and_get_object(addr
, 0);
1562 pr_info("Unknown object at 0x%08lx\n", addr
);
1566 spin_lock_irqsave(&object
->lock
, flags
);
1567 dump_object_info(object
);
1568 spin_unlock_irqrestore(&object
->lock
, flags
);
1575 * We use grey instead of black to ensure we can do future scans on the same
1576 * objects. If we did not do future scans these black objects could
1577 * potentially contain references to newly allocated objects in the future and
1578 * we'd end up with false positives.
1580 static void kmemleak_clear(void)
1582 struct kmemleak_object
*object
;
1583 unsigned long flags
;
1586 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1587 spin_lock_irqsave(&object
->lock
, flags
);
1588 if ((object
->flags
& OBJECT_REPORTED
) &&
1589 unreferenced_object(object
))
1590 __paint_it(object
, KMEMLEAK_GREY
);
1591 spin_unlock_irqrestore(&object
->lock
, flags
);
1595 kmemleak_found_leaks
= false;
1598 static void __kmemleak_do_cleanup(void);
1601 * File write operation to configure kmemleak at run-time. The following
1602 * commands can be written to the /sys/kernel/debug/kmemleak file:
1603 * off - disable kmemleak (irreversible)
1604 * stack=on - enable the task stacks scanning
1605 * stack=off - disable the tasks stacks scanning
1606 * scan=on - start the automatic memory scanning thread
1607 * scan=off - stop the automatic memory scanning thread
1608 * scan=... - set the automatic memory scanning period in seconds (0 to
1610 * scan - trigger a memory scan
1611 * clear - mark all current reported unreferenced kmemleak objects as
1612 * grey to ignore printing them, or free all kmemleak objects
1613 * if kmemleak has been disabled.
1614 * dump=... - dump information about the object found at the given address
1616 static ssize_t
kmemleak_write(struct file
*file
, const char __user
*user_buf
,
1617 size_t size
, loff_t
*ppos
)
1623 buf_size
= min(size
, (sizeof(buf
) - 1));
1624 if (strncpy_from_user(buf
, user_buf
, buf_size
) < 0)
1628 ret
= mutex_lock_interruptible(&scan_mutex
);
1632 if (strncmp(buf
, "clear", 5) == 0) {
1633 if (kmemleak_enabled
)
1636 __kmemleak_do_cleanup();
1640 if (!kmemleak_enabled
) {
1645 if (strncmp(buf
, "off", 3) == 0)
1647 else if (strncmp(buf
, "stack=on", 8) == 0)
1648 kmemleak_stack_scan
= 1;
1649 else if (strncmp(buf
, "stack=off", 9) == 0)
1650 kmemleak_stack_scan
= 0;
1651 else if (strncmp(buf
, "scan=on", 7) == 0)
1652 start_scan_thread();
1653 else if (strncmp(buf
, "scan=off", 8) == 0)
1655 else if (strncmp(buf
, "scan=", 5) == 0) {
1658 ret
= kstrtoul(buf
+ 5, 0, &secs
);
1663 jiffies_scan_wait
= msecs_to_jiffies(secs
* 1000);
1664 start_scan_thread();
1666 } else if (strncmp(buf
, "scan", 4) == 0)
1668 else if (strncmp(buf
, "dump=", 5) == 0)
1669 ret
= dump_str_object_info(buf
+ 5);
1674 mutex_unlock(&scan_mutex
);
1678 /* ignore the rest of the buffer, only one command at a time */
1683 static const struct file_operations kmemleak_fops
= {
1684 .owner
= THIS_MODULE
,
1685 .open
= kmemleak_open
,
1687 .write
= kmemleak_write
,
1688 .llseek
= seq_lseek
,
1689 .release
= seq_release
,
1692 static void __kmemleak_do_cleanup(void)
1694 struct kmemleak_object
*object
;
1697 list_for_each_entry_rcu(object
, &object_list
, object_list
)
1698 delete_object_full(object
->pointer
);
1703 * Stop the memory scanning thread and free the kmemleak internal objects if
1704 * no previous scan thread (otherwise, kmemleak may still have some useful
1705 * information on memory leaks).
1707 static void kmemleak_do_cleanup(struct work_struct
*work
)
1709 mutex_lock(&scan_mutex
);
1712 if (!kmemleak_found_leaks
)
1713 __kmemleak_do_cleanup();
1715 pr_info("Kmemleak disabled without freeing internal data. "
1716 "Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\"\n");
1717 mutex_unlock(&scan_mutex
);
1720 static DECLARE_WORK(cleanup_work
, kmemleak_do_cleanup
);
1723 * Disable kmemleak. No memory allocation/freeing will be traced once this
1724 * function is called. Disabling kmemleak is an irreversible operation.
1726 static void kmemleak_disable(void)
1728 /* atomically check whether it was already invoked */
1729 if (cmpxchg(&kmemleak_error
, 0, 1))
1732 /* stop any memory operation tracing */
1733 kmemleak_enabled
= 0;
1735 /* check whether it is too early for a kernel thread */
1736 if (kmemleak_initialized
)
1737 schedule_work(&cleanup_work
);
1739 pr_info("Kernel memory leak detector disabled\n");
1743 * Allow boot-time kmemleak disabling (enabled by default).
1745 static int kmemleak_boot_config(char *str
)
1749 if (strcmp(str
, "off") == 0)
1751 else if (strcmp(str
, "on") == 0)
1752 kmemleak_skip_disable
= 1;
1757 early_param("kmemleak", kmemleak_boot_config
);
1759 static void __init
print_log_trace(struct early_log
*log
)
1761 struct stack_trace trace
;
1763 trace
.nr_entries
= log
->trace_len
;
1764 trace
.entries
= log
->trace
;
1766 pr_notice("Early log backtrace:\n");
1767 print_stack_trace(&trace
, 2);
1771 * Kmemleak initialization.
1773 void __init
kmemleak_init(void)
1776 unsigned long flags
;
1778 kmemleak_early_log
= 0;
1780 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1781 if (!kmemleak_skip_disable
) {
1787 jiffies_min_age
= msecs_to_jiffies(MSECS_MIN_AGE
);
1788 jiffies_scan_wait
= msecs_to_jiffies(SECS_SCAN_WAIT
* 1000);
1790 object_cache
= KMEM_CACHE(kmemleak_object
, SLAB_NOLEAKTRACE
);
1791 scan_area_cache
= KMEM_CACHE(kmemleak_scan_area
, SLAB_NOLEAKTRACE
);
1793 if (crt_early_log
>= ARRAY_SIZE(early_log
))
1794 pr_warning("Early log buffer exceeded (%d), please increase "
1795 "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log
);
1797 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1798 local_irq_save(flags
);
1799 if (kmemleak_error
) {
1800 local_irq_restore(flags
);
1803 kmemleak_enabled
= 1;
1804 local_irq_restore(flags
);
1807 * This is the point where tracking allocations is safe. Automatic
1808 * scanning is started during the late initcall. Add the early logged
1809 * callbacks to the kmemleak infrastructure.
1811 for (i
= 0; i
< crt_early_log
; i
++) {
1812 struct early_log
*log
= &early_log
[i
];
1814 switch (log
->op_type
) {
1815 case KMEMLEAK_ALLOC
:
1818 case KMEMLEAK_ALLOC_PERCPU
:
1819 early_alloc_percpu(log
);
1822 kmemleak_free(log
->ptr
);
1824 case KMEMLEAK_FREE_PART
:
1825 kmemleak_free_part(log
->ptr
, log
->size
);
1827 case KMEMLEAK_FREE_PERCPU
:
1828 kmemleak_free_percpu(log
->ptr
);
1830 case KMEMLEAK_NOT_LEAK
:
1831 kmemleak_not_leak(log
->ptr
);
1833 case KMEMLEAK_IGNORE
:
1834 kmemleak_ignore(log
->ptr
);
1836 case KMEMLEAK_SCAN_AREA
:
1837 kmemleak_scan_area(log
->ptr
, log
->size
, GFP_KERNEL
);
1839 case KMEMLEAK_NO_SCAN
:
1840 kmemleak_no_scan(log
->ptr
);
1843 kmemleak_warn("Unknown early log operation: %d\n",
1847 if (kmemleak_warning
) {
1848 print_log_trace(log
);
1849 kmemleak_warning
= 0;
1855 * Late initialization function.
1857 static int __init
kmemleak_late_init(void)
1859 struct dentry
*dentry
;
1861 kmemleak_initialized
= 1;
1863 if (kmemleak_error
) {
1865 * Some error occurred and kmemleak was disabled. There is a
1866 * small chance that kmemleak_disable() was called immediately
1867 * after setting kmemleak_initialized and we may end up with
1868 * two clean-up threads but serialized by scan_mutex.
1870 schedule_work(&cleanup_work
);
1874 dentry
= debugfs_create_file("kmemleak", S_IRUGO
, NULL
, NULL
,
1877 pr_warning("Failed to create the debugfs kmemleak file\n");
1878 mutex_lock(&scan_mutex
);
1879 start_scan_thread();
1880 mutex_unlock(&scan_mutex
);
1882 pr_info("Kernel memory leak detector initialized\n");
1886 late_initcall(kmemleak_late_init
);