1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 2008 ARM Limited
6 * Written by Catalin Marinas <catalin.marinas@arm.com>
8 * For more information on the algorithm and kmemleak usage, please see
9 * Documentation/dev-tools/kmemleak.rst.
14 * The following locks and mutexes are used by kmemleak:
16 * - kmemleak_lock (raw_spinlock_t): protects the object_list as well as
17 * del_state modifications and accesses to the object trees
18 * (object_tree_root, object_phys_tree_root, object_percpu_tree_root). The
19 * object_list is the main list holding the metadata (struct
20 * kmemleak_object) for the allocated memory blocks. The object trees are
21 * red black trees used to look-up metadata based on a pointer to the
22 * corresponding memory block. The kmemleak_object structures are added to
23 * the object_list and the object tree root in the create_object() function
24 * called from the kmemleak_alloc{,_phys,_percpu}() callback and removed in
25 * delete_object() called from the kmemleak_free{,_phys,_percpu}() callback
26 * - kmemleak_object.lock (raw_spinlock_t): protects a kmemleak_object.
27 * Accesses to the metadata (e.g. count) are protected by this lock. Note
28 * that some members of this structure may be protected by other means
29 * (atomic or kmemleak_lock). This lock is also held when scanning the
30 * corresponding memory block to avoid the kernel freeing it via the
31 * kmemleak_free() callback. This is less heavyweight than holding a global
32 * lock like kmemleak_lock during scanning.
33 * - scan_mutex (mutex): ensures that only one thread may scan the memory for
34 * unreferenced objects at a time. The gray_list contains the objects which
35 * are already referenced or marked as false positives and need to be
36 * scanned. This list is only modified during a scanning episode when the
37 * scan_mutex is held. At the end of a scan, the gray_list is always empty.
38 * Note that the kmemleak_object.use_count is incremented when an object is
39 * added to the gray_list and therefore cannot be freed. This mutex also
40 * prevents multiple users of the "kmemleak" debugfs file together with
41 * modifications to the memory scanning parameters including the scan_thread
44 * Locks and mutexes are acquired/nested in the following order:
46 * scan_mutex [-> object->lock] -> kmemleak_lock -> other_object->lock (SINGLE_DEPTH_NESTING)
48 * No kmemleak_lock and object->lock nesting is allowed outside scan_mutex
51 * The kmemleak_object structures have a use_count incremented or decremented
52 * using the get_object()/put_object() functions. When the use_count becomes
53 * 0, this count can no longer be incremented and put_object() schedules the
54 * kmemleak_object freeing via an RCU callback. All calls to the get_object()
55 * function must be protected by rcu_read_lock() to avoid accessing a freed
59 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
61 #include <linux/init.h>
62 #include <linux/kernel.h>
63 #include <linux/list.h>
64 #include <linux/sched/signal.h>
65 #include <linux/sched/task.h>
66 #include <linux/sched/task_stack.h>
67 #include <linux/jiffies.h>
68 #include <linux/delay.h>
69 #include <linux/export.h>
70 #include <linux/kthread.h>
71 #include <linux/rbtree.h>
73 #include <linux/debugfs.h>
74 #include <linux/seq_file.h>
75 #include <linux/cpumask.h>
76 #include <linux/spinlock.h>
77 #include <linux/module.h>
78 #include <linux/mutex.h>
79 #include <linux/rcupdate.h>
80 #include <linux/stacktrace.h>
81 #include <linux/stackdepot.h>
82 #include <linux/cache.h>
83 #include <linux/percpu.h>
84 #include <linux/memblock.h>
85 #include <linux/pfn.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/kasan.h>
102 #include <linux/kfence.h>
103 #include <linux/kmemleak.h>
104 #include <linux/memory_hotplug.h>
107 * Kmemleak configuration and common defines.
109 #define MAX_TRACE 16 /* stack trace length */
110 #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
111 #define SECS_FIRST_SCAN 60 /* delay before the first scan */
112 #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
113 #define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
115 #define BYTES_PER_POINTER sizeof(void *)
117 /* scanning area inside a memory block */
118 struct kmemleak_scan_area
{
119 struct hlist_node node
;
124 #define KMEMLEAK_GREY 0
125 #define KMEMLEAK_BLACK -1
128 * Structure holding the metadata for each allocated memory block.
129 * Modifications to such objects should be made while holding the
130 * object->lock. Insertions or deletions from object_list, gray_list or
131 * rb_node are already protected by the corresponding locks or mutex (see
132 * the notes on locking above). These objects are reference-counted
133 * (use_count) and freed using the RCU mechanism.
135 struct kmemleak_object
{
137 unsigned int flags
; /* object status flags */
138 struct list_head object_list
;
139 struct list_head gray_list
;
140 struct rb_node rb_node
;
141 struct rcu_head rcu
; /* object_list lockless traversal */
142 /* object usage count; object freed when use_count == 0 */
144 unsigned int del_state
; /* deletion state */
145 unsigned long pointer
;
147 /* pass surplus references to this pointer */
148 unsigned long excess_ref
;
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 depot_stack_handle_t trace_handle
;
156 /* memory ranges to be scanned inside an object (empty for all) */
157 struct hlist_head area_list
;
158 unsigned long jiffies
; /* creation timestamp */
159 pid_t pid
; /* pid of the current task */
160 char comm
[TASK_COMM_LEN
]; /* executable name */
163 /* flag representing the memory block allocation status */
164 #define OBJECT_ALLOCATED (1 << 0)
165 /* flag set after the first reporting of an unreference object */
166 #define OBJECT_REPORTED (1 << 1)
167 /* flag set to not scan the object */
168 #define OBJECT_NO_SCAN (1 << 2)
169 /* flag set to fully scan the object when scan_area allocation failed */
170 #define OBJECT_FULL_SCAN (1 << 3)
171 /* flag set for object allocated with physical address */
172 #define OBJECT_PHYS (1 << 4)
173 /* flag set for per-CPU pointers */
174 #define OBJECT_PERCPU (1 << 5)
176 /* set when __remove_object() called */
177 #define DELSTATE_REMOVED (1 << 0)
178 /* set to temporarily prevent deletion from object_list */
179 #define DELSTATE_NO_DELETE (1 << 1)
181 #define HEX_PREFIX " "
182 /* number of bytes to print per line; must be 16 or 32 */
183 #define HEX_ROW_SIZE 16
184 /* number of bytes to print at a time (1, 2, 4, 8) */
185 #define HEX_GROUP_SIZE 1
186 /* include ASCII after the hex output */
188 /* max number of lines to be printed */
189 #define HEX_MAX_LINES 2
191 /* the list of all allocated objects */
192 static LIST_HEAD(object_list
);
193 /* the list of gray-colored objects (see color_gray comment below) */
194 static LIST_HEAD(gray_list
);
195 /* memory pool allocation */
196 static struct kmemleak_object mem_pool
[CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE
];
197 static int mem_pool_free_count
= ARRAY_SIZE(mem_pool
);
198 static LIST_HEAD(mem_pool_free_list
);
199 /* search tree for object boundaries */
200 static struct rb_root object_tree_root
= RB_ROOT
;
201 /* search tree for object (with OBJECT_PHYS flag) boundaries */
202 static struct rb_root object_phys_tree_root
= RB_ROOT
;
203 /* search tree for object (with OBJECT_PERCPU flag) boundaries */
204 static struct rb_root object_percpu_tree_root
= RB_ROOT
;
205 /* protecting the access to object_list, object_tree_root (or object_phys_tree_root) */
206 static DEFINE_RAW_SPINLOCK(kmemleak_lock
);
208 /* allocation caches for kmemleak internal data */
209 static struct kmem_cache
*object_cache
;
210 static struct kmem_cache
*scan_area_cache
;
212 /* set if tracing memory operations is enabled */
213 static int kmemleak_enabled
= 1;
214 /* same as above but only for the kmemleak_free() callback */
215 static int kmemleak_free_enabled
= 1;
216 /* set in the late_initcall if there were no errors */
217 static int kmemleak_late_initialized
;
218 /* set if a kmemleak warning was issued */
219 static int kmemleak_warning
;
220 /* set if a fatal kmemleak error has occurred */
221 static int kmemleak_error
;
223 /* minimum and maximum address that may be valid pointers */
224 static unsigned long min_addr
= ULONG_MAX
;
225 static unsigned long max_addr
;
227 static struct task_struct
*scan_thread
;
228 /* used to avoid reporting of recently allocated objects */
229 static unsigned long jiffies_min_age
;
230 static unsigned long jiffies_last_scan
;
231 /* delay between automatic memory scannings */
232 static unsigned long jiffies_scan_wait
;
233 /* enables or disables the task stacks scanning */
234 static int kmemleak_stack_scan
= 1;
235 /* protects the memory scanning, parameters and debug/kmemleak file access */
236 static DEFINE_MUTEX(scan_mutex
);
237 /* setting kmemleak=on, will set this var, skipping the disable */
238 static int kmemleak_skip_disable
;
239 /* If there are leaks that can be reported */
240 static bool kmemleak_found_leaks
;
242 static bool kmemleak_verbose
;
243 module_param_named(verbose
, kmemleak_verbose
, bool, 0600);
245 static void kmemleak_disable(void);
248 * Print a warning and dump the stack trace.
250 #define kmemleak_warn(x...) do { \
253 kmemleak_warning = 1; \
257 * Macro invoked when a serious kmemleak condition occurred and cannot be
258 * recovered from. Kmemleak will be disabled and further allocation/freeing
259 * tracing no longer available.
261 #define kmemleak_stop(x...) do { \
263 kmemleak_disable(); \
266 #define warn_or_seq_printf(seq, fmt, ...) do { \
268 seq_printf(seq, fmt, ##__VA_ARGS__); \
270 pr_warn(fmt, ##__VA_ARGS__); \
273 static void warn_or_seq_hex_dump(struct seq_file
*seq
, int prefix_type
,
274 int rowsize
, int groupsize
, const void *buf
,
275 size_t len
, bool ascii
)
278 seq_hex_dump(seq
, HEX_PREFIX
, prefix_type
, rowsize
, groupsize
,
281 print_hex_dump(KERN_WARNING
, pr_fmt(HEX_PREFIX
), prefix_type
,
282 rowsize
, groupsize
, buf
, len
, ascii
);
286 * Printing of the objects hex dump to the seq file. The number of lines to be
287 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
288 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
289 * with the object->lock held.
291 static void hex_dump_object(struct seq_file
*seq
,
292 struct kmemleak_object
*object
)
294 const u8
*ptr
= (const u8
*)object
->pointer
;
297 if (WARN_ON_ONCE(object
->flags
& (OBJECT_PHYS
| OBJECT_PERCPU
)))
300 /* limit the number of lines to HEX_MAX_LINES */
301 len
= min_t(size_t, object
->size
, HEX_MAX_LINES
* HEX_ROW_SIZE
);
303 warn_or_seq_printf(seq
, " hex dump (first %zu bytes):\n", len
);
304 kasan_disable_current();
305 warn_or_seq_hex_dump(seq
, DUMP_PREFIX_NONE
, HEX_ROW_SIZE
,
306 HEX_GROUP_SIZE
, kasan_reset_tag((void *)ptr
), len
, HEX_ASCII
);
307 kasan_enable_current();
311 * Object colors, encoded with count and min_count:
312 * - white - orphan object, not enough references to it (count < min_count)
313 * - gray - not orphan, not marked as false positive (min_count == 0) or
314 * sufficient references to it (count >= min_count)
315 * - black - ignore, it doesn't contain references (e.g. text section)
316 * (min_count == -1). No function defined for this color.
317 * Newly created objects don't have any color assigned (object->count == -1)
318 * before the next memory scan when they become white.
320 static bool color_white(const struct kmemleak_object
*object
)
322 return object
->count
!= KMEMLEAK_BLACK
&&
323 object
->count
< object
->min_count
;
326 static bool color_gray(const struct kmemleak_object
*object
)
328 return object
->min_count
!= KMEMLEAK_BLACK
&&
329 object
->count
>= object
->min_count
;
333 * Objects are considered unreferenced only if their color is white, they have
334 * not be deleted and have a minimum age to avoid false positives caused by
335 * pointers temporarily stored in CPU registers.
337 static bool unreferenced_object(struct kmemleak_object
*object
)
339 return (color_white(object
) && object
->flags
& OBJECT_ALLOCATED
) &&
340 time_before_eq(object
->jiffies
+ jiffies_min_age
,
345 * Printing of the unreferenced objects information to the seq file. The
346 * print_unreferenced function must be called with the object->lock held.
348 static void print_unreferenced(struct seq_file
*seq
,
349 struct kmemleak_object
*object
)
352 unsigned long *entries
;
353 unsigned int nr_entries
;
355 nr_entries
= stack_depot_fetch(object
->trace_handle
, &entries
);
356 warn_or_seq_printf(seq
, "unreferenced object 0x%08lx (size %zu):\n",
357 object
->pointer
, object
->size
);
358 warn_or_seq_printf(seq
, " comm \"%s\", pid %d, jiffies %lu\n",
359 object
->comm
, object
->pid
, object
->jiffies
);
360 hex_dump_object(seq
, object
);
361 warn_or_seq_printf(seq
, " backtrace (crc %x):\n", object
->checksum
);
363 for (i
= 0; i
< nr_entries
; i
++) {
364 void *ptr
= (void *)entries
[i
];
365 warn_or_seq_printf(seq
, " [<%pK>] %pS\n", ptr
, ptr
);
370 * Print the kmemleak_object information. This function is used mainly for
371 * debugging special cases when kmemleak operations. It must be called with
372 * the object->lock held.
374 static void dump_object_info(struct kmemleak_object
*object
)
376 pr_notice("Object 0x%08lx (size %zu):\n",
377 object
->pointer
, object
->size
);
378 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
379 object
->comm
, object
->pid
, object
->jiffies
);
380 pr_notice(" min_count = %d\n", object
->min_count
);
381 pr_notice(" count = %d\n", object
->count
);
382 pr_notice(" flags = 0x%x\n", object
->flags
);
383 pr_notice(" checksum = %u\n", object
->checksum
);
384 pr_notice(" backtrace:\n");
385 if (object
->trace_handle
)
386 stack_depot_print(object
->trace_handle
);
389 static struct rb_root
*object_tree(unsigned long objflags
)
391 if (objflags
& OBJECT_PHYS
)
392 return &object_phys_tree_root
;
393 if (objflags
& OBJECT_PERCPU
)
394 return &object_percpu_tree_root
;
395 return &object_tree_root
;
399 * Look-up a memory block metadata (kmemleak_object) in the object search
400 * tree based on a pointer value. If alias is 0, only values pointing to the
401 * beginning of the memory block are allowed. The kmemleak_lock must be held
402 * when calling this function.
404 static struct kmemleak_object
*__lookup_object(unsigned long ptr
, int alias
,
405 unsigned int objflags
)
407 struct rb_node
*rb
= object_tree(objflags
)->rb_node
;
408 unsigned long untagged_ptr
= (unsigned long)kasan_reset_tag((void *)ptr
);
411 struct kmemleak_object
*object
;
412 unsigned long untagged_objp
;
414 object
= rb_entry(rb
, struct kmemleak_object
, rb_node
);
415 untagged_objp
= (unsigned long)kasan_reset_tag((void *)object
->pointer
);
417 if (untagged_ptr
< untagged_objp
)
418 rb
= object
->rb_node
.rb_left
;
419 else if (untagged_objp
+ object
->size
<= untagged_ptr
)
420 rb
= object
->rb_node
.rb_right
;
421 else if (untagged_objp
== untagged_ptr
|| alias
)
424 kmemleak_warn("Found object by alias at 0x%08lx\n",
426 dump_object_info(object
);
433 /* Look-up a kmemleak object which allocated with virtual address. */
434 static struct kmemleak_object
*lookup_object(unsigned long ptr
, int alias
)
436 return __lookup_object(ptr
, alias
, 0);
440 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
441 * that once an object's use_count reached 0, the RCU freeing was already
442 * registered and the object should no longer be used. This function must be
443 * called under the protection of rcu_read_lock().
445 static int get_object(struct kmemleak_object
*object
)
447 return atomic_inc_not_zero(&object
->use_count
);
451 * Memory pool allocation and freeing. kmemleak_lock must not be held.
453 static struct kmemleak_object
*mem_pool_alloc(gfp_t gfp
)
456 struct kmemleak_object
*object
;
458 /* try the slab allocator first */
460 object
= kmem_cache_alloc_noprof(object_cache
,
461 gfp_nested_mask(gfp
));
466 /* slab allocation failed, try the memory pool */
467 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
468 object
= list_first_entry_or_null(&mem_pool_free_list
,
469 typeof(*object
), object_list
);
471 list_del(&object
->object_list
);
472 else if (mem_pool_free_count
)
473 object
= &mem_pool
[--mem_pool_free_count
];
475 pr_warn_once("Memory pool empty, consider increasing CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE\n");
476 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
482 * Return the object to either the slab allocator or the memory pool.
484 static void mem_pool_free(struct kmemleak_object
*object
)
488 if (object
< mem_pool
|| object
>= mem_pool
+ ARRAY_SIZE(mem_pool
)) {
489 kmem_cache_free(object_cache
, object
);
493 /* add the object to the memory pool free list */
494 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
495 list_add(&object
->object_list
, &mem_pool_free_list
);
496 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
500 * RCU callback to free a kmemleak_object.
502 static void free_object_rcu(struct rcu_head
*rcu
)
504 struct hlist_node
*tmp
;
505 struct kmemleak_scan_area
*area
;
506 struct kmemleak_object
*object
=
507 container_of(rcu
, struct kmemleak_object
, rcu
);
510 * Once use_count is 0 (guaranteed by put_object), there is no other
511 * code accessing this object, hence no need for locking.
513 hlist_for_each_entry_safe(area
, tmp
, &object
->area_list
, node
) {
514 hlist_del(&area
->node
);
515 kmem_cache_free(scan_area_cache
, area
);
517 mem_pool_free(object
);
521 * Decrement the object use_count. Once the count is 0, free the object using
522 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
523 * delete_object() path, the delayed RCU freeing ensures that there is no
524 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
527 static void put_object(struct kmemleak_object
*object
)
529 if (!atomic_dec_and_test(&object
->use_count
))
532 /* should only get here after delete_object was called */
533 WARN_ON(object
->flags
& OBJECT_ALLOCATED
);
536 * It may be too early for the RCU callbacks, however, there is no
537 * concurrent object_list traversal when !object_cache and all objects
538 * came from the memory pool. Free the object directly.
541 call_rcu(&object
->rcu
, free_object_rcu
);
543 free_object_rcu(&object
->rcu
);
547 * Look up an object in the object search tree and increase its use_count.
549 static struct kmemleak_object
*__find_and_get_object(unsigned long ptr
, int alias
,
550 unsigned int objflags
)
553 struct kmemleak_object
*object
;
556 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
557 object
= __lookup_object(ptr
, alias
, objflags
);
558 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
560 /* check whether the object is still available */
561 if (object
&& !get_object(object
))
568 /* Look up and get an object which allocated with virtual address. */
569 static struct kmemleak_object
*find_and_get_object(unsigned long ptr
, int alias
)
571 return __find_and_get_object(ptr
, alias
, 0);
575 * Remove an object from its object tree and object_list. Must be called with
576 * the kmemleak_lock held _if_ kmemleak is still enabled.
578 static void __remove_object(struct kmemleak_object
*object
)
580 rb_erase(&object
->rb_node
, object_tree(object
->flags
));
581 if (!(object
->del_state
& DELSTATE_NO_DELETE
))
582 list_del_rcu(&object
->object_list
);
583 object
->del_state
|= DELSTATE_REMOVED
;
586 static struct kmemleak_object
*__find_and_remove_object(unsigned long ptr
,
588 unsigned int objflags
)
590 struct kmemleak_object
*object
;
592 object
= __lookup_object(ptr
, alias
, objflags
);
594 __remove_object(object
);
600 * Look up an object in the object search tree and remove it from both object
601 * tree root and object_list. The returned object's use_count should be at
602 * least 1, as initially set by create_object().
604 static struct kmemleak_object
*find_and_remove_object(unsigned long ptr
, int alias
,
605 unsigned int objflags
)
608 struct kmemleak_object
*object
;
610 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
611 object
= __find_and_remove_object(ptr
, alias
, objflags
);
612 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
617 static noinline depot_stack_handle_t
set_track_prepare(void)
619 depot_stack_handle_t trace_handle
;
620 unsigned long entries
[MAX_TRACE
];
621 unsigned int nr_entries
;
624 * Use object_cache to determine whether kmemleak_init() has
625 * been invoked. stack_depot_early_init() is called before
626 * kmemleak_init() in mm_core_init().
630 nr_entries
= stack_trace_save(entries
, ARRAY_SIZE(entries
), 3);
631 trace_handle
= stack_depot_save(entries
, nr_entries
, GFP_NOWAIT
);
636 static struct kmemleak_object
*__alloc_object(gfp_t gfp
)
638 struct kmemleak_object
*object
;
640 object
= mem_pool_alloc(gfp
);
642 pr_warn("Cannot allocate a kmemleak_object structure\n");
647 INIT_LIST_HEAD(&object
->object_list
);
648 INIT_LIST_HEAD(&object
->gray_list
);
649 INIT_HLIST_HEAD(&object
->area_list
);
650 raw_spin_lock_init(&object
->lock
);
651 atomic_set(&object
->use_count
, 1);
652 object
->excess_ref
= 0;
653 object
->count
= 0; /* white color initially */
654 object
->checksum
= 0;
655 object
->del_state
= 0;
657 /* task information */
660 strscpy(object
->comm
, "hardirq");
661 } else if (in_serving_softirq()) {
663 strscpy(object
->comm
, "softirq");
665 object
->pid
= current
->pid
;
667 * There is a small chance of a race with set_task_comm(),
668 * however using get_task_comm() here may cause locking
669 * dependency issues with current->alloc_lock. In the worst
670 * case, the command line is not correct.
672 strscpy(object
->comm
, current
->comm
);
675 /* kernel backtrace */
676 object
->trace_handle
= set_track_prepare();
681 static int __link_object(struct kmemleak_object
*object
, unsigned long ptr
,
682 size_t size
, int min_count
, unsigned int objflags
)
685 struct kmemleak_object
*parent
;
686 struct rb_node
**link
, *rb_parent
;
687 unsigned long untagged_ptr
;
688 unsigned long untagged_objp
;
690 object
->flags
= OBJECT_ALLOCATED
| objflags
;
691 object
->pointer
= ptr
;
692 object
->size
= kfence_ksize((void *)ptr
) ?: size
;
693 object
->min_count
= min_count
;
694 object
->jiffies
= jiffies
;
696 untagged_ptr
= (unsigned long)kasan_reset_tag((void *)ptr
);
698 * Only update min_addr and max_addr with object
699 * storing virtual address.
701 if (!(objflags
& (OBJECT_PHYS
| OBJECT_PERCPU
))) {
702 min_addr
= min(min_addr
, untagged_ptr
);
703 max_addr
= max(max_addr
, untagged_ptr
+ size
);
705 link
= &object_tree(objflags
)->rb_node
;
709 parent
= rb_entry(rb_parent
, struct kmemleak_object
, rb_node
);
710 untagged_objp
= (unsigned long)kasan_reset_tag((void *)parent
->pointer
);
711 if (untagged_ptr
+ size
<= untagged_objp
)
712 link
= &parent
->rb_node
.rb_left
;
713 else if (untagged_objp
+ parent
->size
<= untagged_ptr
)
714 link
= &parent
->rb_node
.rb_right
;
716 kmemleak_stop("Cannot insert 0x%lx into the object search tree (overlaps existing)\n",
719 * No need for parent->lock here since "parent" cannot
720 * be freed while the kmemleak_lock is held.
722 dump_object_info(parent
);
726 rb_link_node(&object
->rb_node
, rb_parent
, link
);
727 rb_insert_color(&object
->rb_node
, object_tree(objflags
));
728 list_add_tail_rcu(&object
->object_list
, &object_list
);
734 * Create the metadata (struct kmemleak_object) corresponding to an allocated
735 * memory block and add it to the object_list and object tree.
737 static void __create_object(unsigned long ptr
, size_t size
,
738 int min_count
, gfp_t gfp
, unsigned int objflags
)
740 struct kmemleak_object
*object
;
744 object
= __alloc_object(gfp
);
748 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
749 ret
= __link_object(object
, ptr
, size
, min_count
, objflags
);
750 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
752 mem_pool_free(object
);
755 /* Create kmemleak object which allocated with virtual address. */
756 static void create_object(unsigned long ptr
, size_t size
,
757 int min_count
, gfp_t gfp
)
759 __create_object(ptr
, size
, min_count
, gfp
, 0);
762 /* Create kmemleak object which allocated with physical address. */
763 static void create_object_phys(unsigned long ptr
, size_t size
,
764 int min_count
, gfp_t gfp
)
766 __create_object(ptr
, size
, min_count
, gfp
, OBJECT_PHYS
);
769 /* Create kmemleak object corresponding to a per-CPU allocation. */
770 static void create_object_percpu(unsigned long ptr
, size_t size
,
771 int min_count
, gfp_t gfp
)
773 __create_object(ptr
, size
, min_count
, gfp
, OBJECT_PERCPU
);
777 * Mark the object as not allocated and schedule RCU freeing via put_object().
779 static void __delete_object(struct kmemleak_object
*object
)
783 WARN_ON(!(object
->flags
& OBJECT_ALLOCATED
));
784 WARN_ON(atomic_read(&object
->use_count
) < 1);
787 * Locking here also ensures that the corresponding memory block
788 * cannot be freed when it is being scanned.
790 raw_spin_lock_irqsave(&object
->lock
, flags
);
791 object
->flags
&= ~OBJECT_ALLOCATED
;
792 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
797 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
800 static void delete_object_full(unsigned long ptr
, unsigned int objflags
)
802 struct kmemleak_object
*object
;
804 object
= find_and_remove_object(ptr
, 0, objflags
);
807 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
812 __delete_object(object
);
816 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
817 * delete it. If the memory block is partially freed, the function may create
818 * additional metadata for the remaining parts of the block.
820 static void delete_object_part(unsigned long ptr
, size_t size
,
821 unsigned int objflags
)
823 struct kmemleak_object
*object
, *object_l
, *object_r
;
824 unsigned long start
, end
, flags
;
826 object_l
= __alloc_object(GFP_KERNEL
);
830 object_r
= __alloc_object(GFP_KERNEL
);
834 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
835 object
= __find_and_remove_object(ptr
, 1, objflags
);
838 kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n",
845 * Create one or two objects that may result from the memory block
846 * split. Note that partial freeing is only done by free_bootmem() and
847 * this happens before kmemleak_init() is called.
849 start
= object
->pointer
;
850 end
= object
->pointer
+ object
->size
;
852 !__link_object(object_l
, start
, ptr
- start
,
853 object
->min_count
, objflags
))
855 if ((ptr
+ size
< end
) &&
856 !__link_object(object_r
, ptr
+ size
, end
- ptr
- size
,
857 object
->min_count
, objflags
))
861 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
863 __delete_object(object
);
867 mem_pool_free(object_l
);
869 mem_pool_free(object_r
);
872 static void __paint_it(struct kmemleak_object
*object
, int color
)
874 object
->min_count
= color
;
875 if (color
== KMEMLEAK_BLACK
)
876 object
->flags
|= OBJECT_NO_SCAN
;
879 static void paint_it(struct kmemleak_object
*object
, int color
)
883 raw_spin_lock_irqsave(&object
->lock
, flags
);
884 __paint_it(object
, color
);
885 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
888 static void paint_ptr(unsigned long ptr
, int color
, unsigned int objflags
)
890 struct kmemleak_object
*object
;
892 object
= __find_and_get_object(ptr
, 0, objflags
);
894 kmemleak_warn("Trying to color unknown object at 0x%08lx as %s\n",
896 (color
== KMEMLEAK_GREY
) ? "Grey" :
897 (color
== KMEMLEAK_BLACK
) ? "Black" : "Unknown");
900 paint_it(object
, color
);
905 * Mark an object permanently as gray-colored so that it can no longer be
906 * reported as a leak. This is used in general to mark a false positive.
908 static void make_gray_object(unsigned long ptr
)
910 paint_ptr(ptr
, KMEMLEAK_GREY
, 0);
914 * Mark the object as black-colored so that it is ignored from scans and
917 static void make_black_object(unsigned long ptr
, unsigned int objflags
)
919 paint_ptr(ptr
, KMEMLEAK_BLACK
, objflags
);
923 * Add a scanning area to the object. If at least one such area is added,
924 * kmemleak will only scan these ranges rather than the whole memory block.
926 static void add_scan_area(unsigned long ptr
, size_t size
, gfp_t gfp
)
929 struct kmemleak_object
*object
;
930 struct kmemleak_scan_area
*area
= NULL
;
931 unsigned long untagged_ptr
;
932 unsigned long untagged_objp
;
934 object
= find_and_get_object(ptr
, 1);
936 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
941 untagged_ptr
= (unsigned long)kasan_reset_tag((void *)ptr
);
942 untagged_objp
= (unsigned long)kasan_reset_tag((void *)object
->pointer
);
945 area
= kmem_cache_alloc_noprof(scan_area_cache
,
946 gfp_nested_mask(gfp
));
948 raw_spin_lock_irqsave(&object
->lock
, flags
);
950 pr_warn_once("Cannot allocate a scan area, scanning the full object\n");
951 /* mark the object for full scan to avoid false positives */
952 object
->flags
|= OBJECT_FULL_SCAN
;
955 if (size
== SIZE_MAX
) {
956 size
= untagged_objp
+ object
->size
- untagged_ptr
;
957 } else if (untagged_ptr
+ size
> untagged_objp
+ object
->size
) {
958 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr
);
959 dump_object_info(object
);
960 kmem_cache_free(scan_area_cache
, area
);
964 INIT_HLIST_NODE(&area
->node
);
968 hlist_add_head(&area
->node
, &object
->area_list
);
970 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
975 * Any surplus references (object already gray) to 'ptr' are passed to
976 * 'excess_ref'. This is used in the vmalloc() case where a pointer to
977 * vm_struct may be used as an alternative reference to the vmalloc'ed object
978 * (see free_thread_stack()).
980 static void object_set_excess_ref(unsigned long ptr
, unsigned long excess_ref
)
983 struct kmemleak_object
*object
;
985 object
= find_and_get_object(ptr
, 0);
987 kmemleak_warn("Setting excess_ref on unknown object at 0x%08lx\n",
992 raw_spin_lock_irqsave(&object
->lock
, flags
);
993 object
->excess_ref
= excess_ref
;
994 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
999 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
1000 * pointer. Such object will not be scanned by kmemleak but references to it
1003 static void object_no_scan(unsigned long ptr
)
1005 unsigned long flags
;
1006 struct kmemleak_object
*object
;
1008 object
= find_and_get_object(ptr
, 0);
1010 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr
);
1014 raw_spin_lock_irqsave(&object
->lock
, flags
);
1015 object
->flags
|= OBJECT_NO_SCAN
;
1016 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1021 * kmemleak_alloc - register a newly allocated object
1022 * @ptr: pointer to beginning of the object
1023 * @size: size of the object
1024 * @min_count: minimum number of references to this object. If during memory
1025 * scanning a number of references less than @min_count is found,
1026 * the object is reported as a memory leak. If @min_count is 0,
1027 * the object is never reported as a leak. If @min_count is -1,
1028 * the object is ignored (not scanned and not reported as a leak)
1029 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1031 * This function is called from the kernel allocators when a new object
1032 * (memory block) is allocated (kmem_cache_alloc, kmalloc etc.).
1034 void __ref
kmemleak_alloc(const void *ptr
, size_t size
, int min_count
,
1037 pr_debug("%s(0x%px, %zu, %d)\n", __func__
, ptr
, size
, min_count
);
1039 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1040 create_object((unsigned long)ptr
, size
, min_count
, gfp
);
1042 EXPORT_SYMBOL_GPL(kmemleak_alloc
);
1045 * kmemleak_alloc_percpu - register a newly allocated __percpu object
1046 * @ptr: __percpu pointer to beginning of the object
1047 * @size: size of the object
1048 * @gfp: flags used for kmemleak internal memory allocations
1050 * This function is called from the kernel percpu allocator when a new object
1051 * (memory block) is allocated (alloc_percpu).
1053 void __ref
kmemleak_alloc_percpu(const void __percpu
*ptr
, size_t size
,
1056 pr_debug("%s(0x%px, %zu)\n", __func__
, ptr
, size
);
1059 * Percpu allocations are only scanned and not reported as leaks
1060 * (min_count is set to 0).
1062 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1063 create_object_percpu((unsigned long)ptr
, size
, 0, gfp
);
1065 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu
);
1068 * kmemleak_vmalloc - register a newly vmalloc'ed object
1069 * @area: pointer to vm_struct
1070 * @size: size of the object
1071 * @gfp: __vmalloc() flags used for kmemleak internal memory allocations
1073 * This function is called from the vmalloc() kernel allocator when a new
1074 * object (memory block) is allocated.
1076 void __ref
kmemleak_vmalloc(const struct vm_struct
*area
, size_t size
, gfp_t gfp
)
1078 pr_debug("%s(0x%px, %zu)\n", __func__
, area
, size
);
1081 * A min_count = 2 is needed because vm_struct contains a reference to
1082 * the virtual address of the vmalloc'ed block.
1084 if (kmemleak_enabled
) {
1085 create_object((unsigned long)area
->addr
, size
, 2, gfp
);
1086 object_set_excess_ref((unsigned long)area
,
1087 (unsigned long)area
->addr
);
1090 EXPORT_SYMBOL_GPL(kmemleak_vmalloc
);
1093 * kmemleak_free - unregister a previously registered object
1094 * @ptr: pointer to beginning of the object
1096 * This function is called from the kernel allocators when an object (memory
1097 * block) is freed (kmem_cache_free, kfree, vfree etc.).
1099 void __ref
kmemleak_free(const void *ptr
)
1101 pr_debug("%s(0x%px)\n", __func__
, ptr
);
1103 if (kmemleak_free_enabled
&& ptr
&& !IS_ERR(ptr
))
1104 delete_object_full((unsigned long)ptr
, 0);
1106 EXPORT_SYMBOL_GPL(kmemleak_free
);
1109 * kmemleak_free_part - partially unregister a previously registered object
1110 * @ptr: pointer to the beginning or inside the object. This also
1111 * represents the start of the range to be freed
1112 * @size: size to be unregistered
1114 * This function is called when only a part of a memory block is freed
1115 * (usually from the bootmem allocator).
1117 void __ref
kmemleak_free_part(const void *ptr
, size_t size
)
1119 pr_debug("%s(0x%px)\n", __func__
, ptr
);
1121 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1122 delete_object_part((unsigned long)ptr
, size
, 0);
1124 EXPORT_SYMBOL_GPL(kmemleak_free_part
);
1127 * kmemleak_free_percpu - unregister a previously registered __percpu object
1128 * @ptr: __percpu pointer to beginning of the object
1130 * This function is called from the kernel percpu allocator when an object
1131 * (memory block) is freed (free_percpu).
1133 void __ref
kmemleak_free_percpu(const void __percpu
*ptr
)
1135 pr_debug("%s(0x%px)\n", __func__
, ptr
);
1137 if (kmemleak_free_enabled
&& ptr
&& !IS_ERR(ptr
))
1138 delete_object_full((unsigned long)ptr
, OBJECT_PERCPU
);
1140 EXPORT_SYMBOL_GPL(kmemleak_free_percpu
);
1143 * kmemleak_update_trace - update object allocation stack trace
1144 * @ptr: pointer to beginning of the object
1146 * Override the object allocation stack trace for cases where the actual
1147 * allocation place is not always useful.
1149 void __ref
kmemleak_update_trace(const void *ptr
)
1151 struct kmemleak_object
*object
;
1152 depot_stack_handle_t trace_handle
;
1153 unsigned long flags
;
1155 pr_debug("%s(0x%px)\n", __func__
, ptr
);
1157 if (!kmemleak_enabled
|| IS_ERR_OR_NULL(ptr
))
1160 object
= find_and_get_object((unsigned long)ptr
, 1);
1163 kmemleak_warn("Updating stack trace for unknown object at %p\n",
1169 trace_handle
= set_track_prepare();
1170 raw_spin_lock_irqsave(&object
->lock
, flags
);
1171 object
->trace_handle
= trace_handle
;
1172 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1176 EXPORT_SYMBOL(kmemleak_update_trace
);
1179 * kmemleak_not_leak - mark an allocated object as false positive
1180 * @ptr: pointer to beginning of the object
1182 * Calling this function on an object will cause the memory block to no longer
1183 * be reported as leak and always be scanned.
1185 void __ref
kmemleak_not_leak(const void *ptr
)
1187 pr_debug("%s(0x%px)\n", __func__
, ptr
);
1189 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1190 make_gray_object((unsigned long)ptr
);
1192 EXPORT_SYMBOL(kmemleak_not_leak
);
1195 * kmemleak_ignore - ignore an allocated object
1196 * @ptr: pointer to beginning of the object
1198 * Calling this function on an object will cause the memory block to be
1199 * ignored (not scanned and not reported as a leak). This is usually done when
1200 * it is known that the corresponding block is not a leak and does not contain
1201 * any references to other allocated memory blocks.
1203 void __ref
kmemleak_ignore(const void *ptr
)
1205 pr_debug("%s(0x%px)\n", __func__
, ptr
);
1207 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1208 make_black_object((unsigned long)ptr
, 0);
1210 EXPORT_SYMBOL(kmemleak_ignore
);
1213 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1214 * @ptr: pointer to beginning or inside the object. This also
1215 * represents the start of the scan area
1216 * @size: size of the scan area
1217 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1219 * This function is used when it is known that only certain parts of an object
1220 * contain references to other objects. Kmemleak will only scan these areas
1221 * reducing the number false negatives.
1223 void __ref
kmemleak_scan_area(const void *ptr
, size_t size
, gfp_t gfp
)
1225 pr_debug("%s(0x%px)\n", __func__
, ptr
);
1227 if (kmemleak_enabled
&& ptr
&& size
&& !IS_ERR(ptr
))
1228 add_scan_area((unsigned long)ptr
, size
, gfp
);
1230 EXPORT_SYMBOL(kmemleak_scan_area
);
1233 * kmemleak_no_scan - do not scan an allocated object
1234 * @ptr: pointer to beginning of the object
1236 * This function notifies kmemleak not to scan the given memory block. Useful
1237 * in situations where it is known that the given object does not contain any
1238 * references to other objects. Kmemleak will not scan such objects reducing
1239 * the number of false negatives.
1241 void __ref
kmemleak_no_scan(const void *ptr
)
1243 pr_debug("%s(0x%px)\n", __func__
, ptr
);
1245 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1246 object_no_scan((unsigned long)ptr
);
1248 EXPORT_SYMBOL(kmemleak_no_scan
);
1251 * kmemleak_alloc_phys - similar to kmemleak_alloc but taking a physical
1253 * @phys: physical address of the object
1254 * @size: size of the object
1255 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1257 void __ref
kmemleak_alloc_phys(phys_addr_t phys
, size_t size
, gfp_t gfp
)
1259 pr_debug("%s(0x%px, %zu)\n", __func__
, &phys
, size
);
1261 if (kmemleak_enabled
)
1263 * Create object with OBJECT_PHYS flag and
1264 * assume min_count 0.
1266 create_object_phys((unsigned long)phys
, size
, 0, gfp
);
1268 EXPORT_SYMBOL(kmemleak_alloc_phys
);
1271 * kmemleak_free_part_phys - similar to kmemleak_free_part but taking a
1272 * physical address argument
1273 * @phys: physical address if the beginning or inside an object. This
1274 * also represents the start of the range to be freed
1275 * @size: size to be unregistered
1277 void __ref
kmemleak_free_part_phys(phys_addr_t phys
, size_t size
)
1279 pr_debug("%s(0x%px)\n", __func__
, &phys
);
1281 if (kmemleak_enabled
)
1282 delete_object_part((unsigned long)phys
, size
, OBJECT_PHYS
);
1284 EXPORT_SYMBOL(kmemleak_free_part_phys
);
1287 * kmemleak_ignore_phys - similar to kmemleak_ignore but taking a physical
1289 * @phys: physical address of the object
1291 void __ref
kmemleak_ignore_phys(phys_addr_t phys
)
1293 pr_debug("%s(0x%px)\n", __func__
, &phys
);
1295 if (kmemleak_enabled
)
1296 make_black_object((unsigned long)phys
, OBJECT_PHYS
);
1298 EXPORT_SYMBOL(kmemleak_ignore_phys
);
1301 * Update an object's checksum and return true if it was modified.
1303 static bool update_checksum(struct kmemleak_object
*object
)
1305 u32 old_csum
= object
->checksum
;
1307 if (WARN_ON_ONCE(object
->flags
& (OBJECT_PHYS
| OBJECT_PERCPU
)))
1310 kasan_disable_current();
1311 kcsan_disable_current();
1312 object
->checksum
= crc32(0, kasan_reset_tag((void *)object
->pointer
), object
->size
);
1313 kasan_enable_current();
1314 kcsan_enable_current();
1316 return object
->checksum
!= old_csum
;
1320 * Update an object's references. object->lock must be held by the caller.
1322 static void update_refs(struct kmemleak_object
*object
)
1324 if (!color_white(object
)) {
1325 /* non-orphan, ignored or new */
1330 * Increase the object's reference count (number of pointers to the
1331 * memory block). If this count reaches the required minimum, the
1332 * object's color will become gray and it will be added to the
1336 if (color_gray(object
)) {
1337 /* put_object() called when removing from gray_list */
1338 WARN_ON(!get_object(object
));
1339 list_add_tail(&object
->gray_list
, &gray_list
);
1344 * Memory scanning is a long process and it needs to be interruptible. This
1345 * function checks whether such interrupt condition occurred.
1347 static int scan_should_stop(void)
1349 if (!kmemleak_enabled
)
1353 * This function may be called from either process or kthread context,
1354 * hence the need to check for both stop conditions.
1357 return signal_pending(current
);
1359 return kthread_should_stop();
1365 * Scan a memory block (exclusive range) for valid pointers and add those
1366 * found to the gray list.
1368 static void scan_block(void *_start
, void *_end
,
1369 struct kmemleak_object
*scanned
)
1372 unsigned long *start
= PTR_ALIGN(_start
, BYTES_PER_POINTER
);
1373 unsigned long *end
= _end
- (BYTES_PER_POINTER
- 1);
1374 unsigned long flags
;
1375 unsigned long untagged_ptr
;
1377 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
1378 for (ptr
= start
; ptr
< end
; ptr
++) {
1379 struct kmemleak_object
*object
;
1380 unsigned long pointer
;
1381 unsigned long excess_ref
;
1383 if (scan_should_stop())
1386 kasan_disable_current();
1387 pointer
= *(unsigned long *)kasan_reset_tag((void *)ptr
);
1388 kasan_enable_current();
1390 untagged_ptr
= (unsigned long)kasan_reset_tag((void *)pointer
);
1391 if (untagged_ptr
< min_addr
|| untagged_ptr
>= max_addr
)
1395 * No need for get_object() here since we hold kmemleak_lock.
1396 * object->use_count cannot be dropped to 0 while the object
1397 * is still present in object_tree_root and object_list
1398 * (with updates protected by kmemleak_lock).
1400 object
= lookup_object(pointer
, 1);
1403 if (object
== scanned
)
1404 /* self referenced, ignore */
1408 * Avoid the lockdep recursive warning on object->lock being
1409 * previously acquired in scan_object(). These locks are
1410 * enclosed by scan_mutex.
1412 raw_spin_lock_nested(&object
->lock
, SINGLE_DEPTH_NESTING
);
1413 /* only pass surplus references (object already gray) */
1414 if (color_gray(object
)) {
1415 excess_ref
= object
->excess_ref
;
1416 /* no need for update_refs() if object already gray */
1419 update_refs(object
);
1421 raw_spin_unlock(&object
->lock
);
1424 object
= lookup_object(excess_ref
, 0);
1427 if (object
== scanned
)
1428 /* circular reference, ignore */
1430 raw_spin_lock_nested(&object
->lock
, SINGLE_DEPTH_NESTING
);
1431 update_refs(object
);
1432 raw_spin_unlock(&object
->lock
);
1435 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
1439 * Scan a large memory block in MAX_SCAN_SIZE chunks to reduce the latency.
1442 static void scan_large_block(void *start
, void *end
)
1446 while (start
< end
) {
1447 next
= min(start
+ MAX_SCAN_SIZE
, end
);
1448 scan_block(start
, next
, NULL
);
1456 * Scan a memory block corresponding to a kmemleak_object. A condition is
1457 * that object->use_count >= 1.
1459 static void scan_object(struct kmemleak_object
*object
)
1461 struct kmemleak_scan_area
*area
;
1462 unsigned long flags
;
1465 * Once the object->lock is acquired, the corresponding memory block
1466 * cannot be freed (the same lock is acquired in delete_object).
1468 raw_spin_lock_irqsave(&object
->lock
, flags
);
1469 if (object
->flags
& OBJECT_NO_SCAN
)
1471 if (!(object
->flags
& OBJECT_ALLOCATED
))
1472 /* already freed object */
1475 if (object
->flags
& OBJECT_PERCPU
) {
1478 for_each_possible_cpu(cpu
) {
1479 void *start
= per_cpu_ptr((void __percpu
*)object
->pointer
, cpu
);
1480 void *end
= start
+ object
->size
;
1482 scan_block(start
, end
, object
);
1484 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1486 raw_spin_lock_irqsave(&object
->lock
, flags
);
1487 if (!(object
->flags
& OBJECT_ALLOCATED
))
1490 } else if (hlist_empty(&object
->area_list
) ||
1491 object
->flags
& OBJECT_FULL_SCAN
) {
1492 void *start
= object
->flags
& OBJECT_PHYS
?
1493 __va((phys_addr_t
)object
->pointer
) :
1494 (void *)object
->pointer
;
1495 void *end
= start
+ object
->size
;
1499 next
= min(start
+ MAX_SCAN_SIZE
, end
);
1500 scan_block(start
, next
, object
);
1506 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1508 raw_spin_lock_irqsave(&object
->lock
, flags
);
1509 } while (object
->flags
& OBJECT_ALLOCATED
);
1511 hlist_for_each_entry(area
, &object
->area_list
, node
)
1512 scan_block((void *)area
->start
,
1513 (void *)(area
->start
+ area
->size
),
1517 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1521 * Scan the objects already referenced (gray objects). More objects will be
1522 * referenced and, if there are no memory leaks, all the objects are scanned.
1524 static void scan_gray_list(void)
1526 struct kmemleak_object
*object
, *tmp
;
1529 * The list traversal is safe for both tail additions and removals
1530 * from inside the loop. The kmemleak objects cannot be freed from
1531 * outside the loop because their use_count was incremented.
1533 object
= list_entry(gray_list
.next
, typeof(*object
), gray_list
);
1534 while (&object
->gray_list
!= &gray_list
) {
1537 /* may add new objects to the list */
1538 if (!scan_should_stop())
1539 scan_object(object
);
1541 tmp
= list_entry(object
->gray_list
.next
, typeof(*object
),
1544 /* remove the object from the list and release it */
1545 list_del(&object
->gray_list
);
1550 WARN_ON(!list_empty(&gray_list
));
1554 * Conditionally call resched() in an object iteration loop while making sure
1555 * that the given object won't go away without RCU read lock by performing a
1556 * get_object() if necessaary.
1558 static void kmemleak_cond_resched(struct kmemleak_object
*object
)
1560 if (!get_object(object
))
1561 return; /* Try next object */
1563 raw_spin_lock_irq(&kmemleak_lock
);
1564 if (object
->del_state
& DELSTATE_REMOVED
)
1565 goto unlock_put
; /* Object removed */
1566 object
->del_state
|= DELSTATE_NO_DELETE
;
1567 raw_spin_unlock_irq(&kmemleak_lock
);
1573 raw_spin_lock_irq(&kmemleak_lock
);
1574 if (object
->del_state
& DELSTATE_REMOVED
)
1575 list_del_rcu(&object
->object_list
);
1576 object
->del_state
&= ~DELSTATE_NO_DELETE
;
1578 raw_spin_unlock_irq(&kmemleak_lock
);
1583 * Scan data sections and all the referenced memory blocks allocated via the
1584 * kernel's standard allocators. This function must be called with the
1587 static void kmemleak_scan(void)
1589 struct kmemleak_object
*object
;
1591 int __maybe_unused i
;
1594 jiffies_last_scan
= jiffies
;
1596 /* prepare the kmemleak_object's */
1598 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1599 raw_spin_lock_irq(&object
->lock
);
1602 * With a few exceptions there should be a maximum of
1603 * 1 reference to any object at this point.
1605 if (atomic_read(&object
->use_count
) > 1) {
1606 pr_debug("object->use_count = %d\n",
1607 atomic_read(&object
->use_count
));
1608 dump_object_info(object
);
1612 /* ignore objects outside lowmem (paint them black) */
1613 if ((object
->flags
& OBJECT_PHYS
) &&
1614 !(object
->flags
& OBJECT_NO_SCAN
)) {
1615 unsigned long phys
= object
->pointer
;
1617 if (PHYS_PFN(phys
) < min_low_pfn
||
1618 PHYS_PFN(phys
+ object
->size
) >= max_low_pfn
)
1619 __paint_it(object
, KMEMLEAK_BLACK
);
1622 /* reset the reference count (whiten the object) */
1624 if (color_gray(object
) && get_object(object
))
1625 list_add_tail(&object
->gray_list
, &gray_list
);
1627 raw_spin_unlock_irq(&object
->lock
);
1630 kmemleak_cond_resched(object
);
1635 /* per-cpu sections scanning */
1636 for_each_possible_cpu(i
)
1637 scan_large_block(__per_cpu_start
+ per_cpu_offset(i
),
1638 __per_cpu_end
+ per_cpu_offset(i
));
1642 * Struct page scanning for each node.
1645 for_each_populated_zone(zone
) {
1646 unsigned long start_pfn
= zone
->zone_start_pfn
;
1647 unsigned long end_pfn
= zone_end_pfn(zone
);
1650 for (pfn
= start_pfn
; pfn
< end_pfn
; pfn
++) {
1651 struct page
*page
= pfn_to_online_page(pfn
);
1659 /* only scan pages belonging to this zone */
1660 if (page_zone(page
) != zone
)
1662 /* only scan if page is in use */
1663 if (page_count(page
) == 0)
1665 scan_block(page
, page
+ 1, NULL
);
1671 * Scanning the task stacks (may introduce false negatives).
1673 if (kmemleak_stack_scan
) {
1674 struct task_struct
*p
, *g
;
1677 for_each_process_thread(g
, p
) {
1678 void *stack
= try_get_task_stack(p
);
1680 scan_block(stack
, stack
+ THREAD_SIZE
, NULL
);
1688 * Scan the objects already referenced from the sections scanned
1694 * Check for new or unreferenced objects modified since the previous
1695 * scan and color them gray until the next scan.
1698 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1700 kmemleak_cond_resched(object
);
1703 * This is racy but we can save the overhead of lock/unlock
1704 * calls. The missed objects, if any, should be caught in
1707 if (!color_white(object
))
1709 raw_spin_lock_irq(&object
->lock
);
1710 if (color_white(object
) && (object
->flags
& OBJECT_ALLOCATED
)
1711 && update_checksum(object
) && get_object(object
)) {
1712 /* color it gray temporarily */
1713 object
->count
= object
->min_count
;
1714 list_add_tail(&object
->gray_list
, &gray_list
);
1716 raw_spin_unlock_irq(&object
->lock
);
1721 * Re-scan the gray list for modified unreferenced objects.
1726 * If scanning was stopped do not report any new unreferenced objects.
1728 if (scan_should_stop())
1732 * Scanning result reporting.
1735 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1737 kmemleak_cond_resched(object
);
1740 * This is racy but we can save the overhead of lock/unlock
1741 * calls. The missed objects, if any, should be caught in
1744 if (!color_white(object
))
1746 raw_spin_lock_irq(&object
->lock
);
1747 if (unreferenced_object(object
) &&
1748 !(object
->flags
& OBJECT_REPORTED
)) {
1749 object
->flags
|= OBJECT_REPORTED
;
1751 if (kmemleak_verbose
)
1752 print_unreferenced(NULL
, object
);
1756 raw_spin_unlock_irq(&object
->lock
);
1761 kmemleak_found_leaks
= true;
1763 pr_info("%d new suspected memory leaks (see /sys/kernel/debug/kmemleak)\n",
1770 * Thread function performing automatic memory scanning. Unreferenced objects
1771 * at the end of a memory scan are reported but only the first time.
1773 static int kmemleak_scan_thread(void *arg
)
1775 static int first_run
= IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN
);
1777 pr_info("Automatic memory scanning thread started\n");
1778 set_user_nice(current
, 10);
1781 * Wait before the first scan to allow the system to fully initialize.
1784 signed long timeout
= msecs_to_jiffies(SECS_FIRST_SCAN
* 1000);
1786 while (timeout
&& !kthread_should_stop())
1787 timeout
= schedule_timeout_interruptible(timeout
);
1790 while (!kthread_should_stop()) {
1791 signed long timeout
= READ_ONCE(jiffies_scan_wait
);
1793 mutex_lock(&scan_mutex
);
1795 mutex_unlock(&scan_mutex
);
1797 /* wait before the next scan */
1798 while (timeout
&& !kthread_should_stop())
1799 timeout
= schedule_timeout_interruptible(timeout
);
1802 pr_info("Automatic memory scanning thread ended\n");
1808 * Start the automatic memory scanning thread. This function must be called
1809 * with the scan_mutex held.
1811 static void start_scan_thread(void)
1815 scan_thread
= kthread_run(kmemleak_scan_thread
, NULL
, "kmemleak");
1816 if (IS_ERR(scan_thread
)) {
1817 pr_warn("Failed to create the scan thread\n");
1823 * Stop the automatic memory scanning thread.
1825 static void stop_scan_thread(void)
1828 kthread_stop(scan_thread
);
1834 * Iterate over the object_list and return the first valid object at or after
1835 * the required position with its use_count incremented. The function triggers
1836 * a memory scanning when the pos argument points to the first position.
1838 static void *kmemleak_seq_start(struct seq_file
*seq
, loff_t
*pos
)
1840 struct kmemleak_object
*object
;
1844 err
= mutex_lock_interruptible(&scan_mutex
);
1846 return ERR_PTR(err
);
1849 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1852 if (get_object(object
))
1861 * Return the next object in the object_list. The function decrements the
1862 * use_count of the previous object and increases that of the next one.
1864 static void *kmemleak_seq_next(struct seq_file
*seq
, void *v
, loff_t
*pos
)
1866 struct kmemleak_object
*prev_obj
= v
;
1867 struct kmemleak_object
*next_obj
= NULL
;
1868 struct kmemleak_object
*obj
= prev_obj
;
1872 list_for_each_entry_continue_rcu(obj
, &object_list
, object_list
) {
1873 if (get_object(obj
)) {
1879 put_object(prev_obj
);
1884 * Decrement the use_count of the last object required, if any.
1886 static void kmemleak_seq_stop(struct seq_file
*seq
, void *v
)
1890 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1891 * waiting was interrupted, so only release it if !IS_ERR.
1894 mutex_unlock(&scan_mutex
);
1901 * Print the information for an unreferenced object to the seq file.
1903 static int kmemleak_seq_show(struct seq_file
*seq
, void *v
)
1905 struct kmemleak_object
*object
= v
;
1906 unsigned long flags
;
1908 raw_spin_lock_irqsave(&object
->lock
, flags
);
1909 if ((object
->flags
& OBJECT_REPORTED
) && unreferenced_object(object
))
1910 print_unreferenced(seq
, object
);
1911 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1915 static const struct seq_operations kmemleak_seq_ops
= {
1916 .start
= kmemleak_seq_start
,
1917 .next
= kmemleak_seq_next
,
1918 .stop
= kmemleak_seq_stop
,
1919 .show
= kmemleak_seq_show
,
1922 static int kmemleak_open(struct inode
*inode
, struct file
*file
)
1924 return seq_open(file
, &kmemleak_seq_ops
);
1927 static int dump_str_object_info(const char *str
)
1929 unsigned long flags
;
1930 struct kmemleak_object
*object
;
1933 if (kstrtoul(str
, 0, &addr
))
1935 object
= find_and_get_object(addr
, 0);
1937 pr_info("Unknown object at 0x%08lx\n", addr
);
1941 raw_spin_lock_irqsave(&object
->lock
, flags
);
1942 dump_object_info(object
);
1943 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1950 * We use grey instead of black to ensure we can do future scans on the same
1951 * objects. If we did not do future scans these black objects could
1952 * potentially contain references to newly allocated objects in the future and
1953 * we'd end up with false positives.
1955 static void kmemleak_clear(void)
1957 struct kmemleak_object
*object
;
1960 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1961 raw_spin_lock_irq(&object
->lock
);
1962 if ((object
->flags
& OBJECT_REPORTED
) &&
1963 unreferenced_object(object
))
1964 __paint_it(object
, KMEMLEAK_GREY
);
1965 raw_spin_unlock_irq(&object
->lock
);
1969 kmemleak_found_leaks
= false;
1972 static void __kmemleak_do_cleanup(void);
1975 * File write operation to configure kmemleak at run-time. The following
1976 * commands can be written to the /sys/kernel/debug/kmemleak file:
1977 * off - disable kmemleak (irreversible)
1978 * stack=on - enable the task stacks scanning
1979 * stack=off - disable the tasks stacks scanning
1980 * scan=on - start the automatic memory scanning thread
1981 * scan=off - stop the automatic memory scanning thread
1982 * scan=... - set the automatic memory scanning period in seconds (0 to
1984 * scan - trigger a memory scan
1985 * clear - mark all current reported unreferenced kmemleak objects as
1986 * grey to ignore printing them, or free all kmemleak objects
1987 * if kmemleak has been disabled.
1988 * dump=... - dump information about the object found at the given address
1990 static ssize_t
kmemleak_write(struct file
*file
, const char __user
*user_buf
,
1991 size_t size
, loff_t
*ppos
)
1997 buf_size
= min(size
, (sizeof(buf
) - 1));
1998 if (strncpy_from_user(buf
, user_buf
, buf_size
) < 0)
2002 ret
= mutex_lock_interruptible(&scan_mutex
);
2006 if (strncmp(buf
, "clear", 5) == 0) {
2007 if (kmemleak_enabled
)
2010 __kmemleak_do_cleanup();
2014 if (!kmemleak_enabled
) {
2019 if (strncmp(buf
, "off", 3) == 0)
2021 else if (strncmp(buf
, "stack=on", 8) == 0)
2022 kmemleak_stack_scan
= 1;
2023 else if (strncmp(buf
, "stack=off", 9) == 0)
2024 kmemleak_stack_scan
= 0;
2025 else if (strncmp(buf
, "scan=on", 7) == 0)
2026 start_scan_thread();
2027 else if (strncmp(buf
, "scan=off", 8) == 0)
2029 else if (strncmp(buf
, "scan=", 5) == 0) {
2031 unsigned long msecs
;
2033 ret
= kstrtouint(buf
+ 5, 0, &secs
);
2037 msecs
= secs
* MSEC_PER_SEC
;
2038 if (msecs
> UINT_MAX
)
2043 WRITE_ONCE(jiffies_scan_wait
, msecs_to_jiffies(msecs
));
2044 start_scan_thread();
2046 } else if (strncmp(buf
, "scan", 4) == 0)
2048 else if (strncmp(buf
, "dump=", 5) == 0)
2049 ret
= dump_str_object_info(buf
+ 5);
2054 mutex_unlock(&scan_mutex
);
2058 /* ignore the rest of the buffer, only one command at a time */
2063 static const struct file_operations kmemleak_fops
= {
2064 .owner
= THIS_MODULE
,
2065 .open
= kmemleak_open
,
2067 .write
= kmemleak_write
,
2068 .llseek
= seq_lseek
,
2069 .release
= seq_release
,
2072 static void __kmemleak_do_cleanup(void)
2074 struct kmemleak_object
*object
, *tmp
;
2077 * Kmemleak has already been disabled, no need for RCU list traversal
2078 * or kmemleak_lock held.
2080 list_for_each_entry_safe(object
, tmp
, &object_list
, object_list
) {
2081 __remove_object(object
);
2082 __delete_object(object
);
2087 * Stop the memory scanning thread and free the kmemleak internal objects if
2088 * no previous scan thread (otherwise, kmemleak may still have some useful
2089 * information on memory leaks).
2091 static void kmemleak_do_cleanup(struct work_struct
*work
)
2095 mutex_lock(&scan_mutex
);
2097 * Once it is made sure that kmemleak_scan has stopped, it is safe to no
2098 * longer track object freeing. Ordering of the scan thread stopping and
2099 * the memory accesses below is guaranteed by the kthread_stop()
2102 kmemleak_free_enabled
= 0;
2103 mutex_unlock(&scan_mutex
);
2105 if (!kmemleak_found_leaks
)
2106 __kmemleak_do_cleanup();
2108 pr_info("Kmemleak disabled without freeing internal data. Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\".\n");
2111 static DECLARE_WORK(cleanup_work
, kmemleak_do_cleanup
);
2114 * Disable kmemleak. No memory allocation/freeing will be traced once this
2115 * function is called. Disabling kmemleak is an irreversible operation.
2117 static void kmemleak_disable(void)
2119 /* atomically check whether it was already invoked */
2120 if (cmpxchg(&kmemleak_error
, 0, 1))
2123 /* stop any memory operation tracing */
2124 kmemleak_enabled
= 0;
2126 /* check whether it is too early for a kernel thread */
2127 if (kmemleak_late_initialized
)
2128 schedule_work(&cleanup_work
);
2130 kmemleak_free_enabled
= 0;
2132 pr_info("Kernel memory leak detector disabled\n");
2136 * Allow boot-time kmemleak disabling (enabled by default).
2138 static int __init
kmemleak_boot_config(char *str
)
2142 if (strcmp(str
, "off") == 0)
2144 else if (strcmp(str
, "on") == 0) {
2145 kmemleak_skip_disable
= 1;
2146 stack_depot_request_early_init();
2152 early_param("kmemleak", kmemleak_boot_config
);
2155 * Kmemleak initialization.
2157 void __init
kmemleak_init(void)
2159 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
2160 if (!kmemleak_skip_disable
) {
2169 jiffies_min_age
= msecs_to_jiffies(MSECS_MIN_AGE
);
2170 jiffies_scan_wait
= msecs_to_jiffies(SECS_SCAN_WAIT
* 1000);
2172 object_cache
= KMEM_CACHE(kmemleak_object
, SLAB_NOLEAKTRACE
);
2173 scan_area_cache
= KMEM_CACHE(kmemleak_scan_area
, SLAB_NOLEAKTRACE
);
2175 /* register the data/bss sections */
2176 create_object((unsigned long)_sdata
, _edata
- _sdata
,
2177 KMEMLEAK_GREY
, GFP_ATOMIC
);
2178 create_object((unsigned long)__bss_start
, __bss_stop
- __bss_start
,
2179 KMEMLEAK_GREY
, GFP_ATOMIC
);
2180 /* only register .data..ro_after_init if not within .data */
2181 if (&__start_ro_after_init
< &_sdata
|| &__end_ro_after_init
> &_edata
)
2182 create_object((unsigned long)__start_ro_after_init
,
2183 __end_ro_after_init
- __start_ro_after_init
,
2184 KMEMLEAK_GREY
, GFP_ATOMIC
);
2188 * Late initialization function.
2190 static int __init
kmemleak_late_init(void)
2192 kmemleak_late_initialized
= 1;
2194 debugfs_create_file("kmemleak", 0644, NULL
, NULL
, &kmemleak_fops
);
2196 if (kmemleak_error
) {
2198 * Some error occurred and kmemleak was disabled. There is a
2199 * small chance that kmemleak_disable() was called immediately
2200 * after setting kmemleak_late_initialized and we may end up with
2201 * two clean-up threads but serialized by scan_mutex.
2203 schedule_work(&cleanup_work
);
2207 if (IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN
)) {
2208 mutex_lock(&scan_mutex
);
2209 start_scan_thread();
2210 mutex_unlock(&scan_mutex
);
2213 pr_info("Kernel memory leak detector initialized (mem pool available: %d)\n",
2214 mem_pool_free_count
);
2218 late_initcall(kmemleak_late_init
);