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 priority search 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/prio_tree.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>
105 * Kmemleak configuration and common defines.
107 #define MAX_TRACE 16 /* stack trace length */
108 #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
109 #define SECS_FIRST_SCAN 60 /* delay before the first scan */
110 #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
111 #define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
113 #define BYTES_PER_POINTER sizeof(void *)
115 /* GFP bitmask for kmemleak internal allocations */
116 #define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
117 __GFP_NORETRY | __GFP_NOMEMALLOC | \
120 /* scanning area inside a memory block */
121 struct kmemleak_scan_area
{
122 struct hlist_node node
;
127 #define KMEMLEAK_GREY 0
128 #define KMEMLEAK_BLACK -1
131 * Structure holding the metadata for each allocated memory block.
132 * Modifications to such objects should be made while holding the
133 * object->lock. Insertions or deletions from object_list, gray_list or
134 * tree_node are already protected by the corresponding locks or mutex (see
135 * the notes on locking above). These objects are reference-counted
136 * (use_count) and freed using the RCU mechanism.
138 struct kmemleak_object
{
140 unsigned long flags
; /* object status flags */
141 struct list_head object_list
;
142 struct list_head gray_list
;
143 struct prio_tree_node tree_node
;
144 struct rcu_head rcu
; /* object_list lockless traversal */
145 /* object usage count; object freed when use_count == 0 */
147 unsigned long pointer
;
149 /* minimum number of a pointers found before it is considered leak */
151 /* the total number of pointers found pointing to this object */
153 /* checksum for detecting modified objects */
155 /* memory ranges to be scanned inside an object (empty for all) */
156 struct hlist_head area_list
;
157 unsigned long trace
[MAX_TRACE
];
158 unsigned int trace_len
;
159 unsigned long jiffies
; /* creation timestamp */
160 pid_t pid
; /* pid of the current task */
161 char comm
[TASK_COMM_LEN
]; /* executable name */
164 /* flag representing the memory block allocation status */
165 #define OBJECT_ALLOCATED (1 << 0)
166 /* flag set after the first reporting of an unreference object */
167 #define OBJECT_REPORTED (1 << 1)
168 /* flag set to not scan the object */
169 #define OBJECT_NO_SCAN (1 << 2)
171 /* number of bytes to print per line; must be 16 or 32 */
172 #define HEX_ROW_SIZE 16
173 /* number of bytes to print at a time (1, 2, 4, 8) */
174 #define HEX_GROUP_SIZE 1
175 /* include ASCII after the hex output */
177 /* max number of lines to be printed */
178 #define HEX_MAX_LINES 2
180 /* the list of all allocated objects */
181 static LIST_HEAD(object_list
);
182 /* the list of gray-colored objects (see color_gray comment below) */
183 static LIST_HEAD(gray_list
);
184 /* prio search tree for object boundaries */
185 static struct prio_tree_root object_tree_root
;
186 /* rw_lock protecting the access to object_list and prio_tree_root */
187 static DEFINE_RWLOCK(kmemleak_lock
);
189 /* allocation caches for kmemleak internal data */
190 static struct kmem_cache
*object_cache
;
191 static struct kmem_cache
*scan_area_cache
;
193 /* set if tracing memory operations is enabled */
194 static atomic_t kmemleak_enabled
= ATOMIC_INIT(0);
195 /* set in the late_initcall if there were no errors */
196 static atomic_t kmemleak_initialized
= ATOMIC_INIT(0);
197 /* enables or disables early logging of the memory operations */
198 static atomic_t kmemleak_early_log
= ATOMIC_INIT(1);
199 /* set if a kmemleak warning was issued */
200 static atomic_t kmemleak_warning
= ATOMIC_INIT(0);
201 /* set if a fatal kmemleak error has occurred */
202 static atomic_t kmemleak_error
= ATOMIC_INIT(0);
204 /* minimum and maximum address that may be valid pointers */
205 static unsigned long min_addr
= ULONG_MAX
;
206 static unsigned long max_addr
;
208 static struct task_struct
*scan_thread
;
209 /* used to avoid reporting of recently allocated objects */
210 static unsigned long jiffies_min_age
;
211 static unsigned long jiffies_last_scan
;
212 /* delay between automatic memory scannings */
213 static signed long jiffies_scan_wait
;
214 /* enables or disables the task stacks scanning */
215 static int kmemleak_stack_scan
= 1;
216 /* protects the memory scanning, parameters and debug/kmemleak file access */
217 static DEFINE_MUTEX(scan_mutex
);
218 /* setting kmemleak=on, will set this var, skipping the disable */
219 static int kmemleak_skip_disable
;
223 * Early object allocation/freeing logging. Kmemleak is initialized after the
224 * kernel allocator. However, both the kernel allocator and kmemleak may
225 * allocate memory blocks which need to be tracked. Kmemleak defines an
226 * arbitrary buffer to hold the allocation/freeing information before it is
230 /* kmemleak operation type for early logging */
242 * Structure holding the information passed to kmemleak callbacks during the
246 int op_type
; /* kmemleak operation type */
247 const void *ptr
; /* allocated/freed memory block */
248 size_t size
; /* memory block size */
249 int min_count
; /* minimum reference count */
250 unsigned long trace
[MAX_TRACE
]; /* stack trace */
251 unsigned int trace_len
; /* stack trace length */
254 /* early logging buffer and current position */
255 static struct early_log
256 early_log
[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE
] __initdata
;
257 static int crt_early_log __initdata
;
259 static void kmemleak_disable(void);
262 * Print a warning and dump the stack trace.
264 #define kmemleak_warn(x...) do { \
267 atomic_set(&kmemleak_warning, 1); \
271 * Macro invoked when a serious kmemleak condition occurred and cannot be
272 * recovered from. Kmemleak will be disabled and further allocation/freeing
273 * tracing no longer available.
275 #define kmemleak_stop(x...) do { \
277 kmemleak_disable(); \
281 * Printing of the objects hex dump to the seq file. The number of lines to be
282 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
283 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
284 * with the object->lock held.
286 static void hex_dump_object(struct seq_file
*seq
,
287 struct kmemleak_object
*object
)
289 const u8
*ptr
= (const u8
*)object
->pointer
;
290 int i
, len
, remaining
;
291 unsigned char linebuf
[HEX_ROW_SIZE
* 5];
293 /* limit the number of lines to HEX_MAX_LINES */
295 min(object
->size
, (size_t)(HEX_MAX_LINES
* HEX_ROW_SIZE
));
297 seq_printf(seq
, " hex dump (first %d bytes):\n", len
);
298 for (i
= 0; i
< len
; i
+= HEX_ROW_SIZE
) {
299 int linelen
= min(remaining
, HEX_ROW_SIZE
);
301 remaining
-= HEX_ROW_SIZE
;
302 hex_dump_to_buffer(ptr
+ i
, linelen
, HEX_ROW_SIZE
,
303 HEX_GROUP_SIZE
, linebuf
, sizeof(linebuf
),
305 seq_printf(seq
, " %s\n", linebuf
);
310 * Object colors, encoded with count and min_count:
311 * - white - orphan object, not enough references to it (count < min_count)
312 * - gray - not orphan, not marked as false positive (min_count == 0) or
313 * sufficient references to it (count >= min_count)
314 * - black - ignore, it doesn't contain references (e.g. text section)
315 * (min_count == -1). No function defined for this color.
316 * Newly created objects don't have any color assigned (object->count == -1)
317 * before the next memory scan when they become white.
319 static bool color_white(const struct kmemleak_object
*object
)
321 return object
->count
!= KMEMLEAK_BLACK
&&
322 object
->count
< object
->min_count
;
325 static bool color_gray(const struct kmemleak_object
*object
)
327 return object
->min_count
!= KMEMLEAK_BLACK
&&
328 object
->count
>= object
->min_count
;
332 * Objects are considered unreferenced only if their color is white, they have
333 * not be deleted and have a minimum age to avoid false positives caused by
334 * pointers temporarily stored in CPU registers.
336 static bool unreferenced_object(struct kmemleak_object
*object
)
338 return (color_white(object
) && object
->flags
& OBJECT_ALLOCATED
) &&
339 time_before_eq(object
->jiffies
+ jiffies_min_age
,
344 * Printing of the unreferenced objects information to the seq file. The
345 * print_unreferenced function must be called with the object->lock held.
347 static void print_unreferenced(struct seq_file
*seq
,
348 struct kmemleak_object
*object
)
351 unsigned int msecs_age
= jiffies_to_msecs(jiffies
- object
->jiffies
);
353 seq_printf(seq
, "unreferenced object 0x%08lx (size %zu):\n",
354 object
->pointer
, object
->size
);
355 seq_printf(seq
, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
356 object
->comm
, object
->pid
, object
->jiffies
,
357 msecs_age
/ 1000, msecs_age
% 1000);
358 hex_dump_object(seq
, object
);
359 seq_printf(seq
, " backtrace:\n");
361 for (i
= 0; i
< object
->trace_len
; i
++) {
362 void *ptr
= (void *)object
->trace
[i
];
363 seq_printf(seq
, " [<%p>] %pS\n", ptr
, ptr
);
368 * Print the kmemleak_object information. This function is used mainly for
369 * debugging special cases when kmemleak operations. It must be called with
370 * the object->lock held.
372 static void dump_object_info(struct kmemleak_object
*object
)
374 struct stack_trace trace
;
376 trace
.nr_entries
= object
->trace_len
;
377 trace
.entries
= object
->trace
;
379 pr_notice("Object 0x%08lx (size %zu):\n",
380 object
->tree_node
.start
, object
->size
);
381 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
382 object
->comm
, object
->pid
, object
->jiffies
);
383 pr_notice(" min_count = %d\n", object
->min_count
);
384 pr_notice(" count = %d\n", object
->count
);
385 pr_notice(" flags = 0x%lx\n", object
->flags
);
386 pr_notice(" checksum = %d\n", object
->checksum
);
387 pr_notice(" backtrace:\n");
388 print_stack_trace(&trace
, 4);
392 * Look-up a memory block metadata (kmemleak_object) in the priority search
393 * tree based on a pointer value. If alias is 0, only values pointing to the
394 * beginning of the memory block are allowed. The kmemleak_lock must be held
395 * when calling this function.
397 static struct kmemleak_object
*lookup_object(unsigned long ptr
, int alias
)
399 struct prio_tree_node
*node
;
400 struct prio_tree_iter iter
;
401 struct kmemleak_object
*object
;
403 prio_tree_iter_init(&iter
, &object_tree_root
, ptr
, ptr
);
404 node
= prio_tree_next(&iter
);
406 object
= prio_tree_entry(node
, struct kmemleak_object
,
408 if (!alias
&& object
->pointer
!= ptr
) {
409 kmemleak_warn("Found object by alias at 0x%08lx\n",
411 dump_object_info(object
);
421 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
422 * that once an object's use_count reached 0, the RCU freeing was already
423 * registered and the object should no longer be used. This function must be
424 * called under the protection of rcu_read_lock().
426 static int get_object(struct kmemleak_object
*object
)
428 return atomic_inc_not_zero(&object
->use_count
);
432 * RCU callback to free a kmemleak_object.
434 static void free_object_rcu(struct rcu_head
*rcu
)
436 struct hlist_node
*elem
, *tmp
;
437 struct kmemleak_scan_area
*area
;
438 struct kmemleak_object
*object
=
439 container_of(rcu
, struct kmemleak_object
, rcu
);
442 * Once use_count is 0 (guaranteed by put_object), there is no other
443 * code accessing this object, hence no need for locking.
445 hlist_for_each_entry_safe(area
, elem
, tmp
, &object
->area_list
, node
) {
447 kmem_cache_free(scan_area_cache
, area
);
449 kmem_cache_free(object_cache
, object
);
453 * Decrement the object use_count. Once the count is 0, free the object using
454 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
455 * delete_object() path, the delayed RCU freeing ensures that there is no
456 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
459 static void put_object(struct kmemleak_object
*object
)
461 if (!atomic_dec_and_test(&object
->use_count
))
464 /* should only get here after delete_object was called */
465 WARN_ON(object
->flags
& OBJECT_ALLOCATED
);
467 call_rcu(&object
->rcu
, free_object_rcu
);
471 * Look up an object in the prio search tree and increase its use_count.
473 static struct kmemleak_object
*find_and_get_object(unsigned long ptr
, int alias
)
476 struct kmemleak_object
*object
= NULL
;
479 read_lock_irqsave(&kmemleak_lock
, flags
);
480 if (ptr
>= min_addr
&& ptr
< max_addr
)
481 object
= lookup_object(ptr
, alias
);
482 read_unlock_irqrestore(&kmemleak_lock
, flags
);
484 /* check whether the object is still available */
485 if (object
&& !get_object(object
))
493 * Save stack trace to the given array of MAX_TRACE size.
495 static int __save_stack_trace(unsigned long *trace
)
497 struct stack_trace stack_trace
;
499 stack_trace
.max_entries
= MAX_TRACE
;
500 stack_trace
.nr_entries
= 0;
501 stack_trace
.entries
= trace
;
502 stack_trace
.skip
= 2;
503 save_stack_trace(&stack_trace
);
505 return stack_trace
.nr_entries
;
509 * Create the metadata (struct kmemleak_object) corresponding to an allocated
510 * memory block and add it to the object_list and object_tree_root.
512 static struct kmemleak_object
*create_object(unsigned long ptr
, size_t size
,
513 int min_count
, gfp_t gfp
)
516 struct kmemleak_object
*object
;
517 struct prio_tree_node
*node
;
519 object
= kmem_cache_alloc(object_cache
, gfp_kmemleak_mask(gfp
));
521 pr_warning("Cannot allocate a kmemleak_object structure\n");
526 INIT_LIST_HEAD(&object
->object_list
);
527 INIT_LIST_HEAD(&object
->gray_list
);
528 INIT_HLIST_HEAD(&object
->area_list
);
529 spin_lock_init(&object
->lock
);
530 atomic_set(&object
->use_count
, 1);
531 object
->flags
= OBJECT_ALLOCATED
;
532 object
->pointer
= ptr
;
534 object
->min_count
= min_count
;
535 object
->count
= 0; /* white color initially */
536 object
->jiffies
= jiffies
;
537 object
->checksum
= 0;
539 /* task information */
542 strncpy(object
->comm
, "hardirq", sizeof(object
->comm
));
543 } else if (in_softirq()) {
545 strncpy(object
->comm
, "softirq", sizeof(object
->comm
));
547 object
->pid
= current
->pid
;
549 * There is a small chance of a race with set_task_comm(),
550 * however using get_task_comm() here may cause locking
551 * dependency issues with current->alloc_lock. In the worst
552 * case, the command line is not correct.
554 strncpy(object
->comm
, current
->comm
, sizeof(object
->comm
));
557 /* kernel backtrace */
558 object
->trace_len
= __save_stack_trace(object
->trace
);
560 INIT_PRIO_TREE_NODE(&object
->tree_node
);
561 object
->tree_node
.start
= ptr
;
562 object
->tree_node
.last
= ptr
+ size
- 1;
564 write_lock_irqsave(&kmemleak_lock
, flags
);
566 min_addr
= min(min_addr
, ptr
);
567 max_addr
= max(max_addr
, ptr
+ size
);
568 node
= prio_tree_insert(&object_tree_root
, &object
->tree_node
);
570 * The code calling the kernel does not yet have the pointer to the
571 * memory block to be able to free it. However, we still hold the
572 * kmemleak_lock here in case parts of the kernel started freeing
573 * random memory blocks.
575 if (node
!= &object
->tree_node
) {
576 kmemleak_stop("Cannot insert 0x%lx into the object search tree "
577 "(already existing)\n", ptr
);
578 object
= lookup_object(ptr
, 1);
579 spin_lock(&object
->lock
);
580 dump_object_info(object
);
581 spin_unlock(&object
->lock
);
585 list_add_tail_rcu(&object
->object_list
, &object_list
);
587 write_unlock_irqrestore(&kmemleak_lock
, flags
);
592 * Remove the metadata (struct kmemleak_object) for a memory block from the
593 * object_list and object_tree_root and decrement its use_count.
595 static void __delete_object(struct kmemleak_object
*object
)
599 write_lock_irqsave(&kmemleak_lock
, flags
);
600 prio_tree_remove(&object_tree_root
, &object
->tree_node
);
601 list_del_rcu(&object
->object_list
);
602 write_unlock_irqrestore(&kmemleak_lock
, flags
);
604 WARN_ON(!(object
->flags
& OBJECT_ALLOCATED
));
605 WARN_ON(atomic_read(&object
->use_count
) < 2);
608 * Locking here also ensures that the corresponding memory block
609 * cannot be freed when it is being scanned.
611 spin_lock_irqsave(&object
->lock
, flags
);
612 object
->flags
&= ~OBJECT_ALLOCATED
;
613 spin_unlock_irqrestore(&object
->lock
, flags
);
618 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
621 static void delete_object_full(unsigned long ptr
)
623 struct kmemleak_object
*object
;
625 object
= find_and_get_object(ptr
, 0);
628 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
633 __delete_object(object
);
638 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
639 * delete it. If the memory block is partially freed, the function may create
640 * additional metadata for the remaining parts of the block.
642 static void delete_object_part(unsigned long ptr
, size_t size
)
644 struct kmemleak_object
*object
;
645 unsigned long start
, end
;
647 object
= find_and_get_object(ptr
, 1);
650 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
651 "(size %zu)\n", ptr
, size
);
655 __delete_object(object
);
658 * Create one or two objects that may result from the memory block
659 * split. Note that partial freeing is only done by free_bootmem() and
660 * this happens before kmemleak_init() is called. The path below is
661 * only executed during early log recording in kmemleak_init(), so
662 * GFP_KERNEL is enough.
664 start
= object
->pointer
;
665 end
= object
->pointer
+ object
->size
;
667 create_object(start
, ptr
- start
, object
->min_count
,
669 if (ptr
+ size
< end
)
670 create_object(ptr
+ size
, end
- ptr
- size
, object
->min_count
,
676 static void __paint_it(struct kmemleak_object
*object
, int color
)
678 object
->min_count
= color
;
679 if (color
== KMEMLEAK_BLACK
)
680 object
->flags
|= OBJECT_NO_SCAN
;
683 static void paint_it(struct kmemleak_object
*object
, int color
)
687 spin_lock_irqsave(&object
->lock
, flags
);
688 __paint_it(object
, color
);
689 spin_unlock_irqrestore(&object
->lock
, flags
);
692 static void paint_ptr(unsigned long ptr
, int color
)
694 struct kmemleak_object
*object
;
696 object
= find_and_get_object(ptr
, 0);
698 kmemleak_warn("Trying to color unknown object "
699 "at 0x%08lx as %s\n", ptr
,
700 (color
== KMEMLEAK_GREY
) ? "Grey" :
701 (color
== KMEMLEAK_BLACK
) ? "Black" : "Unknown");
704 paint_it(object
, color
);
709 * Mark an object permanently as gray-colored so that it can no longer be
710 * reported as a leak. This is used in general to mark a false positive.
712 static void make_gray_object(unsigned long ptr
)
714 paint_ptr(ptr
, KMEMLEAK_GREY
);
718 * Mark the object as black-colored so that it is ignored from scans and
721 static void make_black_object(unsigned long ptr
)
723 paint_ptr(ptr
, KMEMLEAK_BLACK
);
727 * Add a scanning area to the object. If at least one such area is added,
728 * kmemleak will only scan these ranges rather than the whole memory block.
730 static void add_scan_area(unsigned long ptr
, size_t size
, gfp_t gfp
)
733 struct kmemleak_object
*object
;
734 struct kmemleak_scan_area
*area
;
736 object
= find_and_get_object(ptr
, 1);
738 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
743 area
= kmem_cache_alloc(scan_area_cache
, gfp_kmemleak_mask(gfp
));
745 pr_warning("Cannot allocate a scan area\n");
749 spin_lock_irqsave(&object
->lock
, flags
);
750 if (ptr
+ size
> object
->pointer
+ object
->size
) {
751 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr
);
752 dump_object_info(object
);
753 kmem_cache_free(scan_area_cache
, area
);
757 INIT_HLIST_NODE(&area
->node
);
761 hlist_add_head(&area
->node
, &object
->area_list
);
763 spin_unlock_irqrestore(&object
->lock
, flags
);
769 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
770 * pointer. Such object will not be scanned by kmemleak but references to it
773 static void object_no_scan(unsigned long ptr
)
776 struct kmemleak_object
*object
;
778 object
= find_and_get_object(ptr
, 0);
780 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr
);
784 spin_lock_irqsave(&object
->lock
, flags
);
785 object
->flags
|= OBJECT_NO_SCAN
;
786 spin_unlock_irqrestore(&object
->lock
, flags
);
791 * Log an early kmemleak_* call to the early_log buffer. These calls will be
792 * processed later once kmemleak is fully initialized.
794 static void __init
log_early(int op_type
, const void *ptr
, size_t size
,
798 struct early_log
*log
;
800 if (atomic_read(&kmemleak_error
)) {
801 /* kmemleak stopped recording, just count the requests */
806 if (crt_early_log
>= ARRAY_SIZE(early_log
)) {
812 * There is no need for locking since the kernel is still in UP mode
813 * at this stage. Disabling the IRQs is enough.
815 local_irq_save(flags
);
816 log
= &early_log
[crt_early_log
];
817 log
->op_type
= op_type
;
820 log
->min_count
= min_count
;
821 log
->trace_len
= __save_stack_trace(log
->trace
);
823 local_irq_restore(flags
);
827 * Log an early allocated block and populate the stack trace.
829 static void early_alloc(struct early_log
*log
)
831 struct kmemleak_object
*object
;
835 if (!atomic_read(&kmemleak_enabled
) || !log
->ptr
|| IS_ERR(log
->ptr
))
839 * RCU locking needed to ensure object is not freed via put_object().
842 object
= create_object((unsigned long)log
->ptr
, log
->size
,
843 log
->min_count
, GFP_ATOMIC
);
846 spin_lock_irqsave(&object
->lock
, flags
);
847 for (i
= 0; i
< log
->trace_len
; i
++)
848 object
->trace
[i
] = log
->trace
[i
];
849 object
->trace_len
= log
->trace_len
;
850 spin_unlock_irqrestore(&object
->lock
, flags
);
856 * kmemleak_alloc - register a newly allocated object
857 * @ptr: pointer to beginning of the object
858 * @size: size of the object
859 * @min_count: minimum number of references to this object. If during memory
860 * scanning a number of references less than @min_count is found,
861 * the object is reported as a memory leak. If @min_count is 0,
862 * the object is never reported as a leak. If @min_count is -1,
863 * the object is ignored (not scanned and not reported as a leak)
864 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
866 * This function is called from the kernel allocators when a new object
867 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
869 void __ref
kmemleak_alloc(const void *ptr
, size_t size
, int min_count
,
872 pr_debug("%s(0x%p, %zu, %d)\n", __func__
, ptr
, size
, min_count
);
874 if (atomic_read(&kmemleak_enabled
) && ptr
&& !IS_ERR(ptr
))
875 create_object((unsigned long)ptr
, size
, min_count
, gfp
);
876 else if (atomic_read(&kmemleak_early_log
))
877 log_early(KMEMLEAK_ALLOC
, ptr
, size
, min_count
);
879 EXPORT_SYMBOL_GPL(kmemleak_alloc
);
882 * kmemleak_free - unregister a previously registered object
883 * @ptr: pointer to beginning of the object
885 * This function is called from the kernel allocators when an object (memory
886 * block) is freed (kmem_cache_free, kfree, vfree etc.).
888 void __ref
kmemleak_free(const void *ptr
)
890 pr_debug("%s(0x%p)\n", __func__
, ptr
);
892 if (atomic_read(&kmemleak_enabled
) && ptr
&& !IS_ERR(ptr
))
893 delete_object_full((unsigned long)ptr
);
894 else if (atomic_read(&kmemleak_early_log
))
895 log_early(KMEMLEAK_FREE
, ptr
, 0, 0);
897 EXPORT_SYMBOL_GPL(kmemleak_free
);
900 * kmemleak_free_part - partially unregister a previously registered object
901 * @ptr: pointer to the beginning or inside the object. This also
902 * represents the start of the range to be freed
903 * @size: size to be unregistered
905 * This function is called when only a part of a memory block is freed
906 * (usually from the bootmem allocator).
908 void __ref
kmemleak_free_part(const void *ptr
, size_t size
)
910 pr_debug("%s(0x%p)\n", __func__
, ptr
);
912 if (atomic_read(&kmemleak_enabled
) && ptr
&& !IS_ERR(ptr
))
913 delete_object_part((unsigned long)ptr
, size
);
914 else if (atomic_read(&kmemleak_early_log
))
915 log_early(KMEMLEAK_FREE_PART
, ptr
, size
, 0);
917 EXPORT_SYMBOL_GPL(kmemleak_free_part
);
920 * kmemleak_not_leak - mark an allocated object as false positive
921 * @ptr: pointer to beginning of the object
923 * Calling this function on an object will cause the memory block to no longer
924 * be reported as leak and always be scanned.
926 void __ref
kmemleak_not_leak(const void *ptr
)
928 pr_debug("%s(0x%p)\n", __func__
, ptr
);
930 if (atomic_read(&kmemleak_enabled
) && ptr
&& !IS_ERR(ptr
))
931 make_gray_object((unsigned long)ptr
);
932 else if (atomic_read(&kmemleak_early_log
))
933 log_early(KMEMLEAK_NOT_LEAK
, ptr
, 0, 0);
935 EXPORT_SYMBOL(kmemleak_not_leak
);
938 * kmemleak_ignore - ignore an allocated object
939 * @ptr: pointer to beginning of the object
941 * Calling this function on an object will cause the memory block to be
942 * ignored (not scanned and not reported as a leak). This is usually done when
943 * it is known that the corresponding block is not a leak and does not contain
944 * any references to other allocated memory blocks.
946 void __ref
kmemleak_ignore(const void *ptr
)
948 pr_debug("%s(0x%p)\n", __func__
, ptr
);
950 if (atomic_read(&kmemleak_enabled
) && ptr
&& !IS_ERR(ptr
))
951 make_black_object((unsigned long)ptr
);
952 else if (atomic_read(&kmemleak_early_log
))
953 log_early(KMEMLEAK_IGNORE
, ptr
, 0, 0);
955 EXPORT_SYMBOL(kmemleak_ignore
);
958 * kmemleak_scan_area - limit the range to be scanned in an allocated object
959 * @ptr: pointer to beginning or inside the object. This also
960 * represents the start of the scan area
961 * @size: size of the scan area
962 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
964 * This function is used when it is known that only certain parts of an object
965 * contain references to other objects. Kmemleak will only scan these areas
966 * reducing the number false negatives.
968 void __ref
kmemleak_scan_area(const void *ptr
, size_t size
, gfp_t gfp
)
970 pr_debug("%s(0x%p)\n", __func__
, ptr
);
972 if (atomic_read(&kmemleak_enabled
) && ptr
&& !IS_ERR(ptr
))
973 add_scan_area((unsigned long)ptr
, size
, gfp
);
974 else if (atomic_read(&kmemleak_early_log
))
975 log_early(KMEMLEAK_SCAN_AREA
, ptr
, size
, 0);
977 EXPORT_SYMBOL(kmemleak_scan_area
);
980 * kmemleak_no_scan - do not scan an allocated object
981 * @ptr: pointer to beginning of the object
983 * This function notifies kmemleak not to scan the given memory block. Useful
984 * in situations where it is known that the given object does not contain any
985 * references to other objects. Kmemleak will not scan such objects reducing
986 * the number of false negatives.
988 void __ref
kmemleak_no_scan(const void *ptr
)
990 pr_debug("%s(0x%p)\n", __func__
, ptr
);
992 if (atomic_read(&kmemleak_enabled
) && ptr
&& !IS_ERR(ptr
))
993 object_no_scan((unsigned long)ptr
);
994 else if (atomic_read(&kmemleak_early_log
))
995 log_early(KMEMLEAK_NO_SCAN
, ptr
, 0, 0);
997 EXPORT_SYMBOL(kmemleak_no_scan
);
1000 * Update an object's checksum and return true if it was modified.
1002 static bool update_checksum(struct kmemleak_object
*object
)
1004 u32 old_csum
= object
->checksum
;
1006 if (!kmemcheck_is_obj_initialized(object
->pointer
, object
->size
))
1009 object
->checksum
= crc32(0, (void *)object
->pointer
, object
->size
);
1010 return object
->checksum
!= old_csum
;
1014 * Memory scanning is a long process and it needs to be interruptable. This
1015 * function checks whether such interrupt condition occurred.
1017 static int scan_should_stop(void)
1019 if (!atomic_read(&kmemleak_enabled
))
1023 * This function may be called from either process or kthread context,
1024 * hence the need to check for both stop conditions.
1027 return signal_pending(current
);
1029 return kthread_should_stop();
1035 * Scan a memory block (exclusive range) for valid pointers and add those
1036 * found to the gray list.
1038 static void scan_block(void *_start
, void *_end
,
1039 struct kmemleak_object
*scanned
, int allow_resched
)
1042 unsigned long *start
= PTR_ALIGN(_start
, BYTES_PER_POINTER
);
1043 unsigned long *end
= _end
- (BYTES_PER_POINTER
- 1);
1045 for (ptr
= start
; ptr
< end
; ptr
++) {
1046 struct kmemleak_object
*object
;
1047 unsigned long flags
;
1048 unsigned long pointer
;
1052 if (scan_should_stop())
1055 /* don't scan uninitialized memory */
1056 if (!kmemcheck_is_obj_initialized((unsigned long)ptr
,
1062 object
= find_and_get_object(pointer
, 1);
1065 if (object
== scanned
) {
1066 /* self referenced, ignore */
1072 * Avoid the lockdep recursive warning on object->lock being
1073 * previously acquired in scan_object(). These locks are
1074 * enclosed by scan_mutex.
1076 spin_lock_irqsave_nested(&object
->lock
, flags
,
1077 SINGLE_DEPTH_NESTING
);
1078 if (!color_white(object
)) {
1079 /* non-orphan, ignored or new */
1080 spin_unlock_irqrestore(&object
->lock
, flags
);
1086 * Increase the object's reference count (number of pointers
1087 * to the memory block). If this count reaches the required
1088 * minimum, the object's color will become gray and it will be
1089 * added to the gray_list.
1092 if (color_gray(object
)) {
1093 list_add_tail(&object
->gray_list
, &gray_list
);
1094 spin_unlock_irqrestore(&object
->lock
, flags
);
1098 spin_unlock_irqrestore(&object
->lock
, flags
);
1104 * Scan a memory block corresponding to a kmemleak_object. A condition is
1105 * that object->use_count >= 1.
1107 static void scan_object(struct kmemleak_object
*object
)
1109 struct kmemleak_scan_area
*area
;
1110 struct hlist_node
*elem
;
1111 unsigned long flags
;
1114 * Once the object->lock is acquired, the corresponding memory block
1115 * cannot be freed (the same lock is acquired in delete_object).
1117 spin_lock_irqsave(&object
->lock
, flags
);
1118 if (object
->flags
& OBJECT_NO_SCAN
)
1120 if (!(object
->flags
& OBJECT_ALLOCATED
))
1121 /* already freed object */
1123 if (hlist_empty(&object
->area_list
)) {
1124 void *start
= (void *)object
->pointer
;
1125 void *end
= (void *)(object
->pointer
+ object
->size
);
1127 while (start
< end
&& (object
->flags
& OBJECT_ALLOCATED
) &&
1128 !(object
->flags
& OBJECT_NO_SCAN
)) {
1129 scan_block(start
, min(start
+ MAX_SCAN_SIZE
, end
),
1131 start
+= MAX_SCAN_SIZE
;
1133 spin_unlock_irqrestore(&object
->lock
, flags
);
1135 spin_lock_irqsave(&object
->lock
, flags
);
1138 hlist_for_each_entry(area
, elem
, &object
->area_list
, node
)
1139 scan_block((void *)area
->start
,
1140 (void *)(area
->start
+ area
->size
),
1143 spin_unlock_irqrestore(&object
->lock
, flags
);
1147 * Scan the objects already referenced (gray objects). More objects will be
1148 * referenced and, if there are no memory leaks, all the objects are scanned.
1150 static void scan_gray_list(void)
1152 struct kmemleak_object
*object
, *tmp
;
1155 * The list traversal is safe for both tail additions and removals
1156 * from inside the loop. The kmemleak objects cannot be freed from
1157 * outside the loop because their use_count was incremented.
1159 object
= list_entry(gray_list
.next
, typeof(*object
), gray_list
);
1160 while (&object
->gray_list
!= &gray_list
) {
1163 /* may add new objects to the list */
1164 if (!scan_should_stop())
1165 scan_object(object
);
1167 tmp
= list_entry(object
->gray_list
.next
, typeof(*object
),
1170 /* remove the object from the list and release it */
1171 list_del(&object
->gray_list
);
1176 WARN_ON(!list_empty(&gray_list
));
1180 * Scan data sections and all the referenced memory blocks allocated via the
1181 * kernel's standard allocators. This function must be called with the
1184 static void kmemleak_scan(void)
1186 unsigned long flags
;
1187 struct kmemleak_object
*object
;
1191 jiffies_last_scan
= jiffies
;
1193 /* prepare the kmemleak_object's */
1195 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1196 spin_lock_irqsave(&object
->lock
, flags
);
1199 * With a few exceptions there should be a maximum of
1200 * 1 reference to any object at this point.
1202 if (atomic_read(&object
->use_count
) > 1) {
1203 pr_debug("object->use_count = %d\n",
1204 atomic_read(&object
->use_count
));
1205 dump_object_info(object
);
1208 /* reset the reference count (whiten the object) */
1210 if (color_gray(object
) && get_object(object
))
1211 list_add_tail(&object
->gray_list
, &gray_list
);
1213 spin_unlock_irqrestore(&object
->lock
, flags
);
1217 /* data/bss scanning */
1218 scan_block(_sdata
, _edata
, NULL
, 1);
1219 scan_block(__bss_start
, __bss_stop
, NULL
, 1);
1222 /* per-cpu sections scanning */
1223 for_each_possible_cpu(i
)
1224 scan_block(__per_cpu_start
+ per_cpu_offset(i
),
1225 __per_cpu_end
+ per_cpu_offset(i
), NULL
, 1);
1229 * Struct page scanning for each node. The code below is not yet safe
1230 * with MEMORY_HOTPLUG.
1232 for_each_online_node(i
) {
1233 pg_data_t
*pgdat
= NODE_DATA(i
);
1234 unsigned long start_pfn
= pgdat
->node_start_pfn
;
1235 unsigned long end_pfn
= start_pfn
+ pgdat
->node_spanned_pages
;
1238 for (pfn
= start_pfn
; pfn
< end_pfn
; pfn
++) {
1241 if (!pfn_valid(pfn
))
1243 page
= pfn_to_page(pfn
);
1244 /* only scan if page is in use */
1245 if (page_count(page
) == 0)
1247 scan_block(page
, page
+ 1, NULL
, 1);
1252 * Scanning the task stacks (may introduce false negatives).
1254 if (kmemleak_stack_scan
) {
1255 struct task_struct
*p
, *g
;
1257 read_lock(&tasklist_lock
);
1258 do_each_thread(g
, p
) {
1259 scan_block(task_stack_page(p
), task_stack_page(p
) +
1260 THREAD_SIZE
, NULL
, 0);
1261 } while_each_thread(g
, p
);
1262 read_unlock(&tasklist_lock
);
1266 * Scan the objects already referenced from the sections scanned
1272 * Check for new or unreferenced objects modified since the previous
1273 * scan and color them gray until the next scan.
1276 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1277 spin_lock_irqsave(&object
->lock
, flags
);
1278 if (color_white(object
) && (object
->flags
& OBJECT_ALLOCATED
)
1279 && update_checksum(object
) && get_object(object
)) {
1280 /* color it gray temporarily */
1281 object
->count
= object
->min_count
;
1282 list_add_tail(&object
->gray_list
, &gray_list
);
1284 spin_unlock_irqrestore(&object
->lock
, flags
);
1289 * Re-scan the gray list for modified unreferenced objects.
1294 * If scanning was stopped do not report any new unreferenced objects.
1296 if (scan_should_stop())
1300 * Scanning result reporting.
1303 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1304 spin_lock_irqsave(&object
->lock
, flags
);
1305 if (unreferenced_object(object
) &&
1306 !(object
->flags
& OBJECT_REPORTED
)) {
1307 object
->flags
|= OBJECT_REPORTED
;
1310 spin_unlock_irqrestore(&object
->lock
, flags
);
1315 pr_info("%d new suspected memory leaks (see "
1316 "/sys/kernel/debug/kmemleak)\n", new_leaks
);
1321 * Thread function performing automatic memory scanning. Unreferenced objects
1322 * at the end of a memory scan are reported but only the first time.
1324 static int kmemleak_scan_thread(void *arg
)
1326 static int first_run
= 1;
1328 pr_info("Automatic memory scanning thread started\n");
1329 set_user_nice(current
, 10);
1332 * Wait before the first scan to allow the system to fully initialize.
1336 ssleep(SECS_FIRST_SCAN
);
1339 while (!kthread_should_stop()) {
1340 signed long timeout
= jiffies_scan_wait
;
1342 mutex_lock(&scan_mutex
);
1344 mutex_unlock(&scan_mutex
);
1346 /* wait before the next scan */
1347 while (timeout
&& !kthread_should_stop())
1348 timeout
= schedule_timeout_interruptible(timeout
);
1351 pr_info("Automatic memory scanning thread ended\n");
1357 * Start the automatic memory scanning thread. This function must be called
1358 * with the scan_mutex held.
1360 static void start_scan_thread(void)
1364 scan_thread
= kthread_run(kmemleak_scan_thread
, NULL
, "kmemleak");
1365 if (IS_ERR(scan_thread
)) {
1366 pr_warning("Failed to create the scan thread\n");
1372 * Stop the automatic memory scanning thread. This function must be called
1373 * with the scan_mutex held.
1375 static void stop_scan_thread(void)
1378 kthread_stop(scan_thread
);
1384 * Iterate over the object_list and return the first valid object at or after
1385 * the required position with its use_count incremented. The function triggers
1386 * a memory scanning when the pos argument points to the first position.
1388 static void *kmemleak_seq_start(struct seq_file
*seq
, loff_t
*pos
)
1390 struct kmemleak_object
*object
;
1394 err
= mutex_lock_interruptible(&scan_mutex
);
1396 return ERR_PTR(err
);
1399 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1402 if (get_object(object
))
1411 * Return the next object in the object_list. The function decrements the
1412 * use_count of the previous object and increases that of the next one.
1414 static void *kmemleak_seq_next(struct seq_file
*seq
, void *v
, loff_t
*pos
)
1416 struct kmemleak_object
*prev_obj
= v
;
1417 struct kmemleak_object
*next_obj
= NULL
;
1418 struct list_head
*n
= &prev_obj
->object_list
;
1422 list_for_each_continue_rcu(n
, &object_list
) {
1423 struct kmemleak_object
*obj
=
1424 list_entry(n
, struct kmemleak_object
, object_list
);
1425 if (get_object(obj
)) {
1431 put_object(prev_obj
);
1436 * Decrement the use_count of the last object required, if any.
1438 static void kmemleak_seq_stop(struct seq_file
*seq
, void *v
)
1442 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1443 * waiting was interrupted, so only release it if !IS_ERR.
1446 mutex_unlock(&scan_mutex
);
1453 * Print the information for an unreferenced object to the seq file.
1455 static int kmemleak_seq_show(struct seq_file
*seq
, void *v
)
1457 struct kmemleak_object
*object
= v
;
1458 unsigned long flags
;
1460 spin_lock_irqsave(&object
->lock
, flags
);
1461 if ((object
->flags
& OBJECT_REPORTED
) && unreferenced_object(object
))
1462 print_unreferenced(seq
, object
);
1463 spin_unlock_irqrestore(&object
->lock
, flags
);
1467 static const struct seq_operations kmemleak_seq_ops
= {
1468 .start
= kmemleak_seq_start
,
1469 .next
= kmemleak_seq_next
,
1470 .stop
= kmemleak_seq_stop
,
1471 .show
= kmemleak_seq_show
,
1474 static int kmemleak_open(struct inode
*inode
, struct file
*file
)
1476 if (!atomic_read(&kmemleak_enabled
))
1479 return seq_open(file
, &kmemleak_seq_ops
);
1482 static int kmemleak_release(struct inode
*inode
, struct file
*file
)
1484 return seq_release(inode
, file
);
1487 static int dump_str_object_info(const char *str
)
1489 unsigned long flags
;
1490 struct kmemleak_object
*object
;
1493 addr
= simple_strtoul(str
, NULL
, 0);
1494 object
= find_and_get_object(addr
, 0);
1496 pr_info("Unknown object at 0x%08lx\n", addr
);
1500 spin_lock_irqsave(&object
->lock
, flags
);
1501 dump_object_info(object
);
1502 spin_unlock_irqrestore(&object
->lock
, flags
);
1509 * We use grey instead of black to ensure we can do future scans on the same
1510 * objects. If we did not do future scans these black objects could
1511 * potentially contain references to newly allocated objects in the future and
1512 * we'd end up with false positives.
1514 static void kmemleak_clear(void)
1516 struct kmemleak_object
*object
;
1517 unsigned long flags
;
1520 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1521 spin_lock_irqsave(&object
->lock
, flags
);
1522 if ((object
->flags
& OBJECT_REPORTED
) &&
1523 unreferenced_object(object
))
1524 __paint_it(object
, KMEMLEAK_GREY
);
1525 spin_unlock_irqrestore(&object
->lock
, flags
);
1531 * File write operation to configure kmemleak at run-time. The following
1532 * commands can be written to the /sys/kernel/debug/kmemleak file:
1533 * off - disable kmemleak (irreversible)
1534 * stack=on - enable the task stacks scanning
1535 * stack=off - disable the tasks stacks scanning
1536 * scan=on - start the automatic memory scanning thread
1537 * scan=off - stop the automatic memory scanning thread
1538 * scan=... - set the automatic memory scanning period in seconds (0 to
1540 * scan - trigger a memory scan
1541 * clear - mark all current reported unreferenced kmemleak objects as
1542 * grey to ignore printing them
1543 * dump=... - dump information about the object found at the given address
1545 static ssize_t
kmemleak_write(struct file
*file
, const char __user
*user_buf
,
1546 size_t size
, loff_t
*ppos
)
1552 buf_size
= min(size
, (sizeof(buf
) - 1));
1553 if (strncpy_from_user(buf
, user_buf
, buf_size
) < 0)
1557 ret
= mutex_lock_interruptible(&scan_mutex
);
1561 if (strncmp(buf
, "off", 3) == 0)
1563 else if (strncmp(buf
, "stack=on", 8) == 0)
1564 kmemleak_stack_scan
= 1;
1565 else if (strncmp(buf
, "stack=off", 9) == 0)
1566 kmemleak_stack_scan
= 0;
1567 else if (strncmp(buf
, "scan=on", 7) == 0)
1568 start_scan_thread();
1569 else if (strncmp(buf
, "scan=off", 8) == 0)
1571 else if (strncmp(buf
, "scan=", 5) == 0) {
1574 ret
= strict_strtoul(buf
+ 5, 0, &secs
);
1579 jiffies_scan_wait
= msecs_to_jiffies(secs
* 1000);
1580 start_scan_thread();
1582 } else if (strncmp(buf
, "scan", 4) == 0)
1584 else if (strncmp(buf
, "clear", 5) == 0)
1586 else if (strncmp(buf
, "dump=", 5) == 0)
1587 ret
= dump_str_object_info(buf
+ 5);
1592 mutex_unlock(&scan_mutex
);
1596 /* ignore the rest of the buffer, only one command at a time */
1601 static const struct file_operations kmemleak_fops
= {
1602 .owner
= THIS_MODULE
,
1603 .open
= kmemleak_open
,
1605 .write
= kmemleak_write
,
1606 .llseek
= seq_lseek
,
1607 .release
= kmemleak_release
,
1611 * Perform the freeing of the kmemleak internal objects after waiting for any
1612 * current memory scan to complete.
1614 static void kmemleak_do_cleanup(struct work_struct
*work
)
1616 struct kmemleak_object
*object
;
1618 mutex_lock(&scan_mutex
);
1622 list_for_each_entry_rcu(object
, &object_list
, object_list
)
1623 delete_object_full(object
->pointer
);
1625 mutex_unlock(&scan_mutex
);
1628 static DECLARE_WORK(cleanup_work
, kmemleak_do_cleanup
);
1631 * Disable kmemleak. No memory allocation/freeing will be traced once this
1632 * function is called. Disabling kmemleak is an irreversible operation.
1634 static void kmemleak_disable(void)
1636 /* atomically check whether it was already invoked */
1637 if (atomic_cmpxchg(&kmemleak_error
, 0, 1))
1640 /* stop any memory operation tracing */
1641 atomic_set(&kmemleak_enabled
, 0);
1643 /* check whether it is too early for a kernel thread */
1644 if (atomic_read(&kmemleak_initialized
))
1645 schedule_work(&cleanup_work
);
1647 pr_info("Kernel memory leak detector disabled\n");
1651 * Allow boot-time kmemleak disabling (enabled by default).
1653 static int kmemleak_boot_config(char *str
)
1657 if (strcmp(str
, "off") == 0)
1659 else if (strcmp(str
, "on") == 0)
1660 kmemleak_skip_disable
= 1;
1665 early_param("kmemleak", kmemleak_boot_config
);
1667 static void __init
print_log_trace(struct early_log
*log
)
1669 struct stack_trace trace
;
1671 trace
.nr_entries
= log
->trace_len
;
1672 trace
.entries
= log
->trace
;
1674 pr_notice("Early log backtrace:\n");
1675 print_stack_trace(&trace
, 2);
1679 * Kmemleak initialization.
1681 void __init
kmemleak_init(void)
1684 unsigned long flags
;
1686 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1687 if (!kmemleak_skip_disable
) {
1693 jiffies_min_age
= msecs_to_jiffies(MSECS_MIN_AGE
);
1694 jiffies_scan_wait
= msecs_to_jiffies(SECS_SCAN_WAIT
* 1000);
1696 object_cache
= KMEM_CACHE(kmemleak_object
, SLAB_NOLEAKTRACE
);
1697 scan_area_cache
= KMEM_CACHE(kmemleak_scan_area
, SLAB_NOLEAKTRACE
);
1698 INIT_PRIO_TREE_ROOT(&object_tree_root
);
1700 if (crt_early_log
>= ARRAY_SIZE(early_log
))
1701 pr_warning("Early log buffer exceeded (%d), please increase "
1702 "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log
);
1704 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1705 local_irq_save(flags
);
1706 atomic_set(&kmemleak_early_log
, 0);
1707 if (atomic_read(&kmemleak_error
)) {
1708 local_irq_restore(flags
);
1711 atomic_set(&kmemleak_enabled
, 1);
1712 local_irq_restore(flags
);
1715 * This is the point where tracking allocations is safe. Automatic
1716 * scanning is started during the late initcall. Add the early logged
1717 * callbacks to the kmemleak infrastructure.
1719 for (i
= 0; i
< crt_early_log
; i
++) {
1720 struct early_log
*log
= &early_log
[i
];
1722 switch (log
->op_type
) {
1723 case KMEMLEAK_ALLOC
:
1727 kmemleak_free(log
->ptr
);
1729 case KMEMLEAK_FREE_PART
:
1730 kmemleak_free_part(log
->ptr
, log
->size
);
1732 case KMEMLEAK_NOT_LEAK
:
1733 kmemleak_not_leak(log
->ptr
);
1735 case KMEMLEAK_IGNORE
:
1736 kmemleak_ignore(log
->ptr
);
1738 case KMEMLEAK_SCAN_AREA
:
1739 kmemleak_scan_area(log
->ptr
, log
->size
, GFP_KERNEL
);
1741 case KMEMLEAK_NO_SCAN
:
1742 kmemleak_no_scan(log
->ptr
);
1745 kmemleak_warn("Unknown early log operation: %d\n",
1749 if (atomic_read(&kmemleak_warning
)) {
1750 print_log_trace(log
);
1751 atomic_set(&kmemleak_warning
, 0);
1757 * Late initialization function.
1759 static int __init
kmemleak_late_init(void)
1761 struct dentry
*dentry
;
1763 atomic_set(&kmemleak_initialized
, 1);
1765 if (atomic_read(&kmemleak_error
)) {
1767 * Some error occurred and kmemleak was disabled. There is a
1768 * small chance that kmemleak_disable() was called immediately
1769 * after setting kmemleak_initialized and we may end up with
1770 * two clean-up threads but serialized by scan_mutex.
1772 schedule_work(&cleanup_work
);
1776 dentry
= debugfs_create_file("kmemleak", S_IRUGO
, NULL
, NULL
,
1779 pr_warning("Failed to create the debugfs kmemleak file\n");
1780 mutex_lock(&scan_mutex
);
1781 start_scan_thread();
1782 mutex_unlock(&scan_mutex
);
1784 pr_info("Kernel memory leak detector initialized\n");
1788 late_initcall(kmemleak_late_init
);