1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 2008 ARM Limited
6 * Written by Catalin Marinas <catalin.marinas@arm.com>
8 * For more information on the algorithm and kmemleak usage, please see
9 * Documentation/dev-tools/kmemleak.rst.
14 * The following locks and mutexes are used by kmemleak:
16 * - kmemleak_lock (raw_spinlock_t): protects the object_list modifications and
17 * accesses to the object_tree_root (or object_phys_tree_root). The
18 * object_list is the main list holding the metadata (struct kmemleak_object)
19 * for the allocated memory blocks. The object_tree_root and object_phys_tree_root
20 * are red black trees used to look-up metadata based on a pointer to the
21 * corresponding memory block. The object_phys_tree_root is for objects
22 * allocated with physical address. The kmemleak_object structures are
23 * added to the object_list and object_tree_root (or object_phys_tree_root)
24 * in the create_object() function called from the kmemleak_alloc() (or
25 * kmemleak_alloc_phys()) callback and removed in delete_object() called from
26 * the kmemleak_free() callback
27 * - kmemleak_object.lock (raw_spinlock_t): protects a kmemleak_object.
28 * Accesses to the metadata (e.g. count) are protected by this lock. Note
29 * that some members of this structure may be protected by other means
30 * (atomic or kmemleak_lock). This lock is also held when scanning the
31 * corresponding memory block to avoid the kernel freeing it via the
32 * kmemleak_free() callback. This is less heavyweight than holding a global
33 * lock like kmemleak_lock during scanning.
34 * - scan_mutex (mutex): ensures that only one thread may scan the memory for
35 * unreferenced objects at a time. The gray_list contains the objects which
36 * are already referenced or marked as false positives and need to be
37 * scanned. This list is only modified during a scanning episode when the
38 * scan_mutex is held. At the end of a scan, the gray_list is always empty.
39 * Note that the kmemleak_object.use_count is incremented when an object is
40 * added to the gray_list and therefore cannot be freed. This mutex also
41 * prevents multiple users of the "kmemleak" debugfs file together with
42 * modifications to the memory scanning parameters including the scan_thread
45 * Locks and mutexes are acquired/nested in the following order:
47 * scan_mutex [-> object->lock] -> kmemleak_lock -> other_object->lock (SINGLE_DEPTH_NESTING)
49 * No kmemleak_lock and object->lock nesting is allowed outside scan_mutex
52 * The kmemleak_object structures have a use_count incremented or decremented
53 * using the get_object()/put_object() functions. When the use_count becomes
54 * 0, this count can no longer be incremented and put_object() schedules the
55 * kmemleak_object freeing via an RCU callback. All calls to the get_object()
56 * function must be protected by rcu_read_lock() to avoid accessing a freed
60 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
62 #include <linux/init.h>
63 #include <linux/kernel.h>
64 #include <linux/list.h>
65 #include <linux/sched/signal.h>
66 #include <linux/sched/task.h>
67 #include <linux/sched/task_stack.h>
68 #include <linux/jiffies.h>
69 #include <linux/delay.h>
70 #include <linux/export.h>
71 #include <linux/kthread.h>
72 #include <linux/rbtree.h>
74 #include <linux/debugfs.h>
75 #include <linux/seq_file.h>
76 #include <linux/cpumask.h>
77 #include <linux/spinlock.h>
78 #include <linux/module.h>
79 #include <linux/mutex.h>
80 #include <linux/rcupdate.h>
81 #include <linux/stacktrace.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 /* GFP bitmask for kmemleak internal allocations */
118 #define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC | \
119 __GFP_NOLOCKDEP)) | \
120 __GFP_NORETRY | __GFP_NOMEMALLOC | \
123 /* scanning area inside a memory block */
124 struct kmemleak_scan_area
{
125 struct hlist_node node
;
130 #define KMEMLEAK_GREY 0
131 #define KMEMLEAK_BLACK -1
134 * Structure holding the metadata for each allocated memory block.
135 * Modifications to such objects should be made while holding the
136 * object->lock. Insertions or deletions from object_list, gray_list or
137 * rb_node are already protected by the corresponding locks or mutex (see
138 * the notes on locking above). These objects are reference-counted
139 * (use_count) and freed using the RCU mechanism.
141 struct kmemleak_object
{
143 unsigned int flags
; /* object status flags */
144 struct list_head object_list
;
145 struct list_head gray_list
;
146 struct rb_node rb_node
;
147 struct rcu_head rcu
; /* object_list lockless traversal */
148 /* object usage count; object freed when use_count == 0 */
150 unsigned long pointer
;
152 /* pass surplus references to this pointer */
153 unsigned long excess_ref
;
154 /* minimum number of a pointers found before it is considered leak */
156 /* the total number of pointers found pointing to this object */
158 /* checksum for detecting modified objects */
160 /* memory ranges to be scanned inside an object (empty for all) */
161 struct hlist_head area_list
;
162 unsigned long trace
[MAX_TRACE
];
163 unsigned int trace_len
;
164 unsigned long jiffies
; /* creation timestamp */
165 pid_t pid
; /* pid of the current task */
166 char comm
[TASK_COMM_LEN
]; /* executable name */
169 /* flag representing the memory block allocation status */
170 #define OBJECT_ALLOCATED (1 << 0)
171 /* flag set after the first reporting of an unreference object */
172 #define OBJECT_REPORTED (1 << 1)
173 /* flag set to not scan the object */
174 #define OBJECT_NO_SCAN (1 << 2)
175 /* flag set to fully scan the object when scan_area allocation failed */
176 #define OBJECT_FULL_SCAN (1 << 3)
177 /* flag set for object allocated with physical address */
178 #define OBJECT_PHYS (1 << 4)
180 #define HEX_PREFIX " "
181 /* number of bytes to print per line; must be 16 or 32 */
182 #define HEX_ROW_SIZE 16
183 /* number of bytes to print at a time (1, 2, 4, 8) */
184 #define HEX_GROUP_SIZE 1
185 /* include ASCII after the hex output */
187 /* max number of lines to be printed */
188 #define HEX_MAX_LINES 2
190 /* the list of all allocated objects */
191 static LIST_HEAD(object_list
);
192 /* the list of gray-colored objects (see color_gray comment below) */
193 static LIST_HEAD(gray_list
);
194 /* memory pool allocation */
195 static struct kmemleak_object mem_pool
[CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE
];
196 static int mem_pool_free_count
= ARRAY_SIZE(mem_pool
);
197 static LIST_HEAD(mem_pool_free_list
);
198 /* search tree for object boundaries */
199 static struct rb_root object_tree_root
= RB_ROOT
;
200 /* search tree for object (with OBJECT_PHYS flag) boundaries */
201 static struct rb_root object_phys_tree_root
= RB_ROOT
;
202 /* protecting the access to object_list, object_tree_root (or object_phys_tree_root) */
203 static DEFINE_RAW_SPINLOCK(kmemleak_lock
);
205 /* allocation caches for kmemleak internal data */
206 static struct kmem_cache
*object_cache
;
207 static struct kmem_cache
*scan_area_cache
;
209 /* set if tracing memory operations is enabled */
210 static int kmemleak_enabled
= 1;
211 /* same as above but only for the kmemleak_free() callback */
212 static int kmemleak_free_enabled
= 1;
213 /* set in the late_initcall if there were no errors */
214 static int kmemleak_initialized
;
215 /* set if a kmemleak warning was issued */
216 static int kmemleak_warning
;
217 /* set if a fatal kmemleak error has occurred */
218 static int kmemleak_error
;
220 /* minimum and maximum address that may be valid pointers */
221 static unsigned long min_addr
= ULONG_MAX
;
222 static unsigned long max_addr
;
224 static struct task_struct
*scan_thread
;
225 /* used to avoid reporting of recently allocated objects */
226 static unsigned long jiffies_min_age
;
227 static unsigned long jiffies_last_scan
;
228 /* delay between automatic memory scannings */
229 static unsigned long jiffies_scan_wait
;
230 /* enables or disables the task stacks scanning */
231 static int kmemleak_stack_scan
= 1;
232 /* protects the memory scanning, parameters and debug/kmemleak file access */
233 static DEFINE_MUTEX(scan_mutex
);
234 /* setting kmemleak=on, will set this var, skipping the disable */
235 static int kmemleak_skip_disable
;
236 /* If there are leaks that can be reported */
237 static bool kmemleak_found_leaks
;
239 static bool kmemleak_verbose
;
240 module_param_named(verbose
, kmemleak_verbose
, bool, 0600);
242 static void kmemleak_disable(void);
245 * Print a warning and dump the stack trace.
247 #define kmemleak_warn(x...) do { \
250 kmemleak_warning = 1; \
254 * Macro invoked when a serious kmemleak condition occurred and cannot be
255 * recovered from. Kmemleak will be disabled and further allocation/freeing
256 * tracing no longer available.
258 #define kmemleak_stop(x...) do { \
260 kmemleak_disable(); \
263 #define warn_or_seq_printf(seq, fmt, ...) do { \
265 seq_printf(seq, fmt, ##__VA_ARGS__); \
267 pr_warn(fmt, ##__VA_ARGS__); \
270 static void warn_or_seq_hex_dump(struct seq_file
*seq
, int prefix_type
,
271 int rowsize
, int groupsize
, const void *buf
,
272 size_t len
, bool ascii
)
275 seq_hex_dump(seq
, HEX_PREFIX
, prefix_type
, rowsize
, groupsize
,
278 print_hex_dump(KERN_WARNING
, pr_fmt(HEX_PREFIX
), prefix_type
,
279 rowsize
, groupsize
, buf
, len
, ascii
);
283 * Printing of the objects hex dump to the seq file. The number of lines to be
284 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
285 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
286 * with the object->lock held.
288 static void hex_dump_object(struct seq_file
*seq
,
289 struct kmemleak_object
*object
)
291 const u8
*ptr
= (const u8
*)object
->pointer
;
294 if (WARN_ON_ONCE(object
->flags
& OBJECT_PHYS
))
297 /* limit the number of lines to HEX_MAX_LINES */
298 len
= min_t(size_t, object
->size
, HEX_MAX_LINES
* HEX_ROW_SIZE
);
300 warn_or_seq_printf(seq
, " hex dump (first %zu bytes):\n", len
);
301 kasan_disable_current();
302 warn_or_seq_hex_dump(seq
, DUMP_PREFIX_NONE
, HEX_ROW_SIZE
,
303 HEX_GROUP_SIZE
, kasan_reset_tag((void *)ptr
), len
, HEX_ASCII
);
304 kasan_enable_current();
308 * Object colors, encoded with count and min_count:
309 * - white - orphan object, not enough references to it (count < min_count)
310 * - gray - not orphan, not marked as false positive (min_count == 0) or
311 * sufficient references to it (count >= min_count)
312 * - black - ignore, it doesn't contain references (e.g. text section)
313 * (min_count == -1). No function defined for this color.
314 * Newly created objects don't have any color assigned (object->count == -1)
315 * before the next memory scan when they become white.
317 static bool color_white(const struct kmemleak_object
*object
)
319 return object
->count
!= KMEMLEAK_BLACK
&&
320 object
->count
< object
->min_count
;
323 static bool color_gray(const struct kmemleak_object
*object
)
325 return object
->min_count
!= KMEMLEAK_BLACK
&&
326 object
->count
>= object
->min_count
;
330 * Objects are considered unreferenced only if their color is white, they have
331 * not be deleted and have a minimum age to avoid false positives caused by
332 * pointers temporarily stored in CPU registers.
334 static bool unreferenced_object(struct kmemleak_object
*object
)
336 return (color_white(object
) && object
->flags
& OBJECT_ALLOCATED
) &&
337 time_before_eq(object
->jiffies
+ jiffies_min_age
,
342 * Printing of the unreferenced objects information to the seq file. The
343 * print_unreferenced function must be called with the object->lock held.
345 static void print_unreferenced(struct seq_file
*seq
,
346 struct kmemleak_object
*object
)
349 unsigned int msecs_age
= jiffies_to_msecs(jiffies
- object
->jiffies
);
351 warn_or_seq_printf(seq
, "unreferenced object 0x%08lx (size %zu):\n",
352 object
->pointer
, object
->size
);
353 warn_or_seq_printf(seq
, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
354 object
->comm
, object
->pid
, object
->jiffies
,
355 msecs_age
/ 1000, msecs_age
% 1000);
356 hex_dump_object(seq
, object
);
357 warn_or_seq_printf(seq
, " backtrace:\n");
359 for (i
= 0; i
< object
->trace_len
; i
++) {
360 void *ptr
= (void *)object
->trace
[i
];
361 warn_or_seq_printf(seq
, " [<%p>] %pS\n", ptr
, ptr
);
366 * Print the kmemleak_object information. This function is used mainly for
367 * debugging special cases when kmemleak operations. It must be called with
368 * the object->lock held.
370 static void dump_object_info(struct kmemleak_object
*object
)
372 pr_notice("Object 0x%08lx (size %zu):\n",
373 object
->pointer
, object
->size
);
374 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
375 object
->comm
, object
->pid
, object
->jiffies
);
376 pr_notice(" min_count = %d\n", object
->min_count
);
377 pr_notice(" count = %d\n", object
->count
);
378 pr_notice(" flags = 0x%x\n", object
->flags
);
379 pr_notice(" checksum = %u\n", object
->checksum
);
380 pr_notice(" backtrace:\n");
381 stack_trace_print(object
->trace
, object
->trace_len
, 4);
385 * Look-up a memory block metadata (kmemleak_object) in the object search
386 * tree based on a pointer value. If alias is 0, only values pointing to the
387 * beginning of the memory block are allowed. The kmemleak_lock must be held
388 * when calling this function.
390 static struct kmemleak_object
*__lookup_object(unsigned long ptr
, int alias
,
393 struct rb_node
*rb
= is_phys
? object_phys_tree_root
.rb_node
:
394 object_tree_root
.rb_node
;
395 unsigned long untagged_ptr
= (unsigned long)kasan_reset_tag((void *)ptr
);
398 struct kmemleak_object
*object
;
399 unsigned long untagged_objp
;
401 object
= rb_entry(rb
, struct kmemleak_object
, rb_node
);
402 untagged_objp
= (unsigned long)kasan_reset_tag((void *)object
->pointer
);
404 if (untagged_ptr
< untagged_objp
)
405 rb
= object
->rb_node
.rb_left
;
406 else if (untagged_objp
+ object
->size
<= untagged_ptr
)
407 rb
= object
->rb_node
.rb_right
;
408 else if (untagged_objp
== untagged_ptr
|| alias
)
411 kmemleak_warn("Found object by alias at 0x%08lx\n",
413 dump_object_info(object
);
420 /* Look-up a kmemleak object which allocated with virtual address. */
421 static struct kmemleak_object
*lookup_object(unsigned long ptr
, int alias
)
423 return __lookup_object(ptr
, alias
, false);
427 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
428 * that once an object's use_count reached 0, the RCU freeing was already
429 * registered and the object should no longer be used. This function must be
430 * called under the protection of rcu_read_lock().
432 static int get_object(struct kmemleak_object
*object
)
434 return atomic_inc_not_zero(&object
->use_count
);
438 * Memory pool allocation and freeing. kmemleak_lock must not be held.
440 static struct kmemleak_object
*mem_pool_alloc(gfp_t gfp
)
443 struct kmemleak_object
*object
;
445 /* try the slab allocator first */
447 object
= kmem_cache_alloc(object_cache
, gfp_kmemleak_mask(gfp
));
452 /* slab allocation failed, try the memory pool */
453 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
454 object
= list_first_entry_or_null(&mem_pool_free_list
,
455 typeof(*object
), object_list
);
457 list_del(&object
->object_list
);
458 else if (mem_pool_free_count
)
459 object
= &mem_pool
[--mem_pool_free_count
];
461 pr_warn_once("Memory pool empty, consider increasing CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE\n");
462 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
468 * Return the object to either the slab allocator or the memory pool.
470 static void mem_pool_free(struct kmemleak_object
*object
)
474 if (object
< mem_pool
|| object
>= mem_pool
+ ARRAY_SIZE(mem_pool
)) {
475 kmem_cache_free(object_cache
, object
);
479 /* add the object to the memory pool free list */
480 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
481 list_add(&object
->object_list
, &mem_pool_free_list
);
482 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
486 * RCU callback to free a kmemleak_object.
488 static void free_object_rcu(struct rcu_head
*rcu
)
490 struct hlist_node
*tmp
;
491 struct kmemleak_scan_area
*area
;
492 struct kmemleak_object
*object
=
493 container_of(rcu
, struct kmemleak_object
, rcu
);
496 * Once use_count is 0 (guaranteed by put_object), there is no other
497 * code accessing this object, hence no need for locking.
499 hlist_for_each_entry_safe(area
, tmp
, &object
->area_list
, node
) {
500 hlist_del(&area
->node
);
501 kmem_cache_free(scan_area_cache
, area
);
503 mem_pool_free(object
);
507 * Decrement the object use_count. Once the count is 0, free the object using
508 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
509 * delete_object() path, the delayed RCU freeing ensures that there is no
510 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
513 static void put_object(struct kmemleak_object
*object
)
515 if (!atomic_dec_and_test(&object
->use_count
))
518 /* should only get here after delete_object was called */
519 WARN_ON(object
->flags
& OBJECT_ALLOCATED
);
522 * It may be too early for the RCU callbacks, however, there is no
523 * concurrent object_list traversal when !object_cache and all objects
524 * came from the memory pool. Free the object directly.
527 call_rcu(&object
->rcu
, free_object_rcu
);
529 free_object_rcu(&object
->rcu
);
533 * Look up an object in the object search tree and increase its use_count.
535 static struct kmemleak_object
*__find_and_get_object(unsigned long ptr
, int alias
,
539 struct kmemleak_object
*object
;
542 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
543 object
= __lookup_object(ptr
, alias
, is_phys
);
544 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
546 /* check whether the object is still available */
547 if (object
&& !get_object(object
))
554 /* Look up and get an object which allocated with virtual address. */
555 static struct kmemleak_object
*find_and_get_object(unsigned long ptr
, int alias
)
557 return __find_and_get_object(ptr
, alias
, false);
561 * Remove an object from the object_tree_root (or object_phys_tree_root)
562 * and object_list. Must be called with the kmemleak_lock held _if_ kmemleak
565 static void __remove_object(struct kmemleak_object
*object
)
567 rb_erase(&object
->rb_node
, object
->flags
& OBJECT_PHYS
?
568 &object_phys_tree_root
:
570 list_del_rcu(&object
->object_list
);
574 * Look up an object in the object search tree and remove it from both
575 * object_tree_root (or object_phys_tree_root) and object_list. The
576 * returned object's use_count should be at least 1, as initially set
577 * by create_object().
579 static struct kmemleak_object
*find_and_remove_object(unsigned long ptr
, int alias
,
583 struct kmemleak_object
*object
;
585 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
586 object
= __lookup_object(ptr
, alias
, is_phys
);
588 __remove_object(object
);
589 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
595 * Save stack trace to the given array of MAX_TRACE size.
597 static int __save_stack_trace(unsigned long *trace
)
599 return stack_trace_save(trace
, MAX_TRACE
, 2);
603 * Create the metadata (struct kmemleak_object) corresponding to an allocated
604 * memory block and add it to the object_list and object_tree_root (or
605 * object_phys_tree_root).
607 static void __create_object(unsigned long ptr
, size_t size
,
608 int min_count
, gfp_t gfp
, bool is_phys
)
611 struct kmemleak_object
*object
, *parent
;
612 struct rb_node
**link
, *rb_parent
;
613 unsigned long untagged_ptr
;
614 unsigned long untagged_objp
;
616 object
= mem_pool_alloc(gfp
);
618 pr_warn("Cannot allocate a kmemleak_object structure\n");
623 INIT_LIST_HEAD(&object
->object_list
);
624 INIT_LIST_HEAD(&object
->gray_list
);
625 INIT_HLIST_HEAD(&object
->area_list
);
626 raw_spin_lock_init(&object
->lock
);
627 atomic_set(&object
->use_count
, 1);
628 object
->flags
= OBJECT_ALLOCATED
| (is_phys
? OBJECT_PHYS
: 0);
629 object
->pointer
= ptr
;
630 object
->size
= kfence_ksize((void *)ptr
) ?: size
;
631 object
->excess_ref
= 0;
632 object
->min_count
= min_count
;
633 object
->count
= 0; /* white color initially */
634 object
->jiffies
= jiffies
;
635 object
->checksum
= 0;
637 /* task information */
640 strncpy(object
->comm
, "hardirq", sizeof(object
->comm
));
641 } else if (in_serving_softirq()) {
643 strncpy(object
->comm
, "softirq", sizeof(object
->comm
));
645 object
->pid
= current
->pid
;
647 * There is a small chance of a race with set_task_comm(),
648 * however using get_task_comm() here may cause locking
649 * dependency issues with current->alloc_lock. In the worst
650 * case, the command line is not correct.
652 strncpy(object
->comm
, current
->comm
, sizeof(object
->comm
));
655 /* kernel backtrace */
656 object
->trace_len
= __save_stack_trace(object
->trace
);
658 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
660 untagged_ptr
= (unsigned long)kasan_reset_tag((void *)ptr
);
662 * Only update min_addr and max_addr with object
663 * storing virtual address.
666 min_addr
= min(min_addr
, untagged_ptr
);
667 max_addr
= max(max_addr
, untagged_ptr
+ size
);
669 link
= is_phys
? &object_phys_tree_root
.rb_node
:
670 &object_tree_root
.rb_node
;
674 parent
= rb_entry(rb_parent
, struct kmemleak_object
, rb_node
);
675 untagged_objp
= (unsigned long)kasan_reset_tag((void *)parent
->pointer
);
676 if (untagged_ptr
+ size
<= untagged_objp
)
677 link
= &parent
->rb_node
.rb_left
;
678 else if (untagged_objp
+ parent
->size
<= untagged_ptr
)
679 link
= &parent
->rb_node
.rb_right
;
681 kmemleak_stop("Cannot insert 0x%lx into the object search tree (overlaps existing)\n",
684 * No need for parent->lock here since "parent" cannot
685 * be freed while the kmemleak_lock is held.
687 dump_object_info(parent
);
688 kmem_cache_free(object_cache
, object
);
692 rb_link_node(&object
->rb_node
, rb_parent
, link
);
693 rb_insert_color(&object
->rb_node
, is_phys
? &object_phys_tree_root
:
696 list_add_tail_rcu(&object
->object_list
, &object_list
);
698 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
701 /* Create kmemleak object which allocated with virtual address. */
702 static void create_object(unsigned long ptr
, size_t size
,
703 int min_count
, gfp_t gfp
)
705 __create_object(ptr
, size
, min_count
, gfp
, false);
708 /* Create kmemleak object which allocated with physical address. */
709 static void create_object_phys(unsigned long ptr
, size_t size
,
710 int min_count
, gfp_t gfp
)
712 __create_object(ptr
, size
, min_count
, gfp
, true);
716 * Mark the object as not allocated and schedule RCU freeing via put_object().
718 static void __delete_object(struct kmemleak_object
*object
)
722 WARN_ON(!(object
->flags
& OBJECT_ALLOCATED
));
723 WARN_ON(atomic_read(&object
->use_count
) < 1);
726 * Locking here also ensures that the corresponding memory block
727 * cannot be freed when it is being scanned.
729 raw_spin_lock_irqsave(&object
->lock
, flags
);
730 object
->flags
&= ~OBJECT_ALLOCATED
;
731 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
736 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
739 static void delete_object_full(unsigned long ptr
)
741 struct kmemleak_object
*object
;
743 object
= find_and_remove_object(ptr
, 0, false);
746 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
751 __delete_object(object
);
755 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
756 * delete it. If the memory block is partially freed, the function may create
757 * additional metadata for the remaining parts of the block.
759 static void delete_object_part(unsigned long ptr
, size_t size
, bool is_phys
)
761 struct kmemleak_object
*object
;
762 unsigned long start
, end
;
764 object
= find_and_remove_object(ptr
, 1, is_phys
);
767 kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n",
774 * Create one or two objects that may result from the memory block
775 * split. Note that partial freeing is only done by free_bootmem() and
776 * this happens before kmemleak_init() is called.
778 start
= object
->pointer
;
779 end
= object
->pointer
+ object
->size
;
781 __create_object(start
, ptr
- start
, object
->min_count
,
782 GFP_KERNEL
, is_phys
);
783 if (ptr
+ size
< end
)
784 __create_object(ptr
+ size
, end
- ptr
- size
, object
->min_count
,
785 GFP_KERNEL
, is_phys
);
787 __delete_object(object
);
790 static void __paint_it(struct kmemleak_object
*object
, int color
)
792 object
->min_count
= color
;
793 if (color
== KMEMLEAK_BLACK
)
794 object
->flags
|= OBJECT_NO_SCAN
;
797 static void paint_it(struct kmemleak_object
*object
, int color
)
801 raw_spin_lock_irqsave(&object
->lock
, flags
);
802 __paint_it(object
, color
);
803 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
806 static void paint_ptr(unsigned long ptr
, int color
, bool is_phys
)
808 struct kmemleak_object
*object
;
810 object
= __find_and_get_object(ptr
, 0, is_phys
);
812 kmemleak_warn("Trying to color unknown object at 0x%08lx as %s\n",
814 (color
== KMEMLEAK_GREY
) ? "Grey" :
815 (color
== KMEMLEAK_BLACK
) ? "Black" : "Unknown");
818 paint_it(object
, color
);
823 * Mark an object permanently as gray-colored so that it can no longer be
824 * reported as a leak. This is used in general to mark a false positive.
826 static void make_gray_object(unsigned long ptr
)
828 paint_ptr(ptr
, KMEMLEAK_GREY
, false);
832 * Mark the object as black-colored so that it is ignored from scans and
835 static void make_black_object(unsigned long ptr
, bool is_phys
)
837 paint_ptr(ptr
, KMEMLEAK_BLACK
, is_phys
);
841 * Add a scanning area to the object. If at least one such area is added,
842 * kmemleak will only scan these ranges rather than the whole memory block.
844 static void add_scan_area(unsigned long ptr
, size_t size
, gfp_t gfp
)
847 struct kmemleak_object
*object
;
848 struct kmemleak_scan_area
*area
= NULL
;
849 unsigned long untagged_ptr
;
850 unsigned long untagged_objp
;
852 object
= find_and_get_object(ptr
, 1);
854 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
859 untagged_ptr
= (unsigned long)kasan_reset_tag((void *)ptr
);
860 untagged_objp
= (unsigned long)kasan_reset_tag((void *)object
->pointer
);
863 area
= kmem_cache_alloc(scan_area_cache
, gfp_kmemleak_mask(gfp
));
865 raw_spin_lock_irqsave(&object
->lock
, flags
);
867 pr_warn_once("Cannot allocate a scan area, scanning the full object\n");
868 /* mark the object for full scan to avoid false positives */
869 object
->flags
|= OBJECT_FULL_SCAN
;
872 if (size
== SIZE_MAX
) {
873 size
= untagged_objp
+ object
->size
- untagged_ptr
;
874 } else if (untagged_ptr
+ size
> untagged_objp
+ object
->size
) {
875 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr
);
876 dump_object_info(object
);
877 kmem_cache_free(scan_area_cache
, area
);
881 INIT_HLIST_NODE(&area
->node
);
885 hlist_add_head(&area
->node
, &object
->area_list
);
887 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
892 * Any surplus references (object already gray) to 'ptr' are passed to
893 * 'excess_ref'. This is used in the vmalloc() case where a pointer to
894 * vm_struct may be used as an alternative reference to the vmalloc'ed object
895 * (see free_thread_stack()).
897 static void object_set_excess_ref(unsigned long ptr
, unsigned long excess_ref
)
900 struct kmemleak_object
*object
;
902 object
= find_and_get_object(ptr
, 0);
904 kmemleak_warn("Setting excess_ref on unknown object at 0x%08lx\n",
909 raw_spin_lock_irqsave(&object
->lock
, flags
);
910 object
->excess_ref
= excess_ref
;
911 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
916 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
917 * pointer. Such object will not be scanned by kmemleak but references to it
920 static void object_no_scan(unsigned long ptr
)
923 struct kmemleak_object
*object
;
925 object
= find_and_get_object(ptr
, 0);
927 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr
);
931 raw_spin_lock_irqsave(&object
->lock
, flags
);
932 object
->flags
|= OBJECT_NO_SCAN
;
933 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
938 * kmemleak_alloc - register a newly allocated object
939 * @ptr: pointer to beginning of the object
940 * @size: size of the object
941 * @min_count: minimum number of references to this object. If during memory
942 * scanning a number of references less than @min_count is found,
943 * the object is reported as a memory leak. If @min_count is 0,
944 * the object is never reported as a leak. If @min_count is -1,
945 * the object is ignored (not scanned and not reported as a leak)
946 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
948 * This function is called from the kernel allocators when a new object
949 * (memory block) is allocated (kmem_cache_alloc, kmalloc etc.).
951 void __ref
kmemleak_alloc(const void *ptr
, size_t size
, int min_count
,
954 pr_debug("%s(0x%p, %zu, %d)\n", __func__
, ptr
, size
, min_count
);
956 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
957 create_object((unsigned long)ptr
, size
, min_count
, gfp
);
959 EXPORT_SYMBOL_GPL(kmemleak_alloc
);
962 * kmemleak_alloc_percpu - register a newly allocated __percpu object
963 * @ptr: __percpu pointer to beginning of the object
964 * @size: size of the object
965 * @gfp: flags used for kmemleak internal memory allocations
967 * This function is called from the kernel percpu allocator when a new object
968 * (memory block) is allocated (alloc_percpu).
970 void __ref
kmemleak_alloc_percpu(const void __percpu
*ptr
, size_t size
,
975 pr_debug("%s(0x%p, %zu)\n", __func__
, ptr
, size
);
978 * Percpu allocations are only scanned and not reported as leaks
979 * (min_count is set to 0).
981 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
982 for_each_possible_cpu(cpu
)
983 create_object((unsigned long)per_cpu_ptr(ptr
, cpu
),
986 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu
);
989 * kmemleak_vmalloc - register a newly vmalloc'ed object
990 * @area: pointer to vm_struct
991 * @size: size of the object
992 * @gfp: __vmalloc() flags used for kmemleak internal memory allocations
994 * This function is called from the vmalloc() kernel allocator when a new
995 * object (memory block) is allocated.
997 void __ref
kmemleak_vmalloc(const struct vm_struct
*area
, size_t size
, gfp_t gfp
)
999 pr_debug("%s(0x%p, %zu)\n", __func__
, area
, size
);
1002 * A min_count = 2 is needed because vm_struct contains a reference to
1003 * the virtual address of the vmalloc'ed block.
1005 if (kmemleak_enabled
) {
1006 create_object((unsigned long)area
->addr
, size
, 2, gfp
);
1007 object_set_excess_ref((unsigned long)area
,
1008 (unsigned long)area
->addr
);
1011 EXPORT_SYMBOL_GPL(kmemleak_vmalloc
);
1014 * kmemleak_free - unregister a previously registered object
1015 * @ptr: pointer to beginning of the object
1017 * This function is called from the kernel allocators when an object (memory
1018 * block) is freed (kmem_cache_free, kfree, vfree etc.).
1020 void __ref
kmemleak_free(const void *ptr
)
1022 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1024 if (kmemleak_free_enabled
&& ptr
&& !IS_ERR(ptr
))
1025 delete_object_full((unsigned long)ptr
);
1027 EXPORT_SYMBOL_GPL(kmemleak_free
);
1030 * kmemleak_free_part - partially unregister a previously registered object
1031 * @ptr: pointer to the beginning or inside the object. This also
1032 * represents the start of the range to be freed
1033 * @size: size to be unregistered
1035 * This function is called when only a part of a memory block is freed
1036 * (usually from the bootmem allocator).
1038 void __ref
kmemleak_free_part(const void *ptr
, size_t size
)
1040 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1042 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1043 delete_object_part((unsigned long)ptr
, size
, false);
1045 EXPORT_SYMBOL_GPL(kmemleak_free_part
);
1048 * kmemleak_free_percpu - unregister a previously registered __percpu object
1049 * @ptr: __percpu pointer to beginning of the object
1051 * This function is called from the kernel percpu allocator when an object
1052 * (memory block) is freed (free_percpu).
1054 void __ref
kmemleak_free_percpu(const void __percpu
*ptr
)
1058 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1060 if (kmemleak_free_enabled
&& ptr
&& !IS_ERR(ptr
))
1061 for_each_possible_cpu(cpu
)
1062 delete_object_full((unsigned long)per_cpu_ptr(ptr
,
1065 EXPORT_SYMBOL_GPL(kmemleak_free_percpu
);
1068 * kmemleak_update_trace - update object allocation stack trace
1069 * @ptr: pointer to beginning of the object
1071 * Override the object allocation stack trace for cases where the actual
1072 * allocation place is not always useful.
1074 void __ref
kmemleak_update_trace(const void *ptr
)
1076 struct kmemleak_object
*object
;
1077 unsigned long flags
;
1079 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1081 if (!kmemleak_enabled
|| IS_ERR_OR_NULL(ptr
))
1084 object
= find_and_get_object((unsigned long)ptr
, 1);
1087 kmemleak_warn("Updating stack trace for unknown object at %p\n",
1093 raw_spin_lock_irqsave(&object
->lock
, flags
);
1094 object
->trace_len
= __save_stack_trace(object
->trace
);
1095 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1099 EXPORT_SYMBOL(kmemleak_update_trace
);
1102 * kmemleak_not_leak - mark an allocated object as false positive
1103 * @ptr: pointer to beginning of the object
1105 * Calling this function on an object will cause the memory block to no longer
1106 * be reported as leak and always be scanned.
1108 void __ref
kmemleak_not_leak(const void *ptr
)
1110 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1112 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1113 make_gray_object((unsigned long)ptr
);
1115 EXPORT_SYMBOL(kmemleak_not_leak
);
1118 * kmemleak_ignore - ignore an allocated object
1119 * @ptr: pointer to beginning of the object
1121 * Calling this function on an object will cause the memory block to be
1122 * ignored (not scanned and not reported as a leak). This is usually done when
1123 * it is known that the corresponding block is not a leak and does not contain
1124 * any references to other allocated memory blocks.
1126 void __ref
kmemleak_ignore(const void *ptr
)
1128 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1130 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1131 make_black_object((unsigned long)ptr
, false);
1133 EXPORT_SYMBOL(kmemleak_ignore
);
1136 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1137 * @ptr: pointer to beginning or inside the object. This also
1138 * represents the start of the scan area
1139 * @size: size of the scan area
1140 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1142 * This function is used when it is known that only certain parts of an object
1143 * contain references to other objects. Kmemleak will only scan these areas
1144 * reducing the number false negatives.
1146 void __ref
kmemleak_scan_area(const void *ptr
, size_t size
, gfp_t gfp
)
1148 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1150 if (kmemleak_enabled
&& ptr
&& size
&& !IS_ERR(ptr
))
1151 add_scan_area((unsigned long)ptr
, size
, gfp
);
1153 EXPORT_SYMBOL(kmemleak_scan_area
);
1156 * kmemleak_no_scan - do not scan an allocated object
1157 * @ptr: pointer to beginning of the object
1159 * This function notifies kmemleak not to scan the given memory block. Useful
1160 * in situations where it is known that the given object does not contain any
1161 * references to other objects. Kmemleak will not scan such objects reducing
1162 * the number of false negatives.
1164 void __ref
kmemleak_no_scan(const void *ptr
)
1166 pr_debug("%s(0x%p)\n", __func__
, ptr
);
1168 if (kmemleak_enabled
&& ptr
&& !IS_ERR(ptr
))
1169 object_no_scan((unsigned long)ptr
);
1171 EXPORT_SYMBOL(kmemleak_no_scan
);
1174 * kmemleak_alloc_phys - similar to kmemleak_alloc but taking a physical
1176 * @phys: physical address of the object
1177 * @size: size of the object
1178 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1180 void __ref
kmemleak_alloc_phys(phys_addr_t phys
, size_t size
, gfp_t gfp
)
1182 pr_debug("%s(0x%pa, %zu)\n", __func__
, &phys
, size
);
1184 if (kmemleak_enabled
)
1186 * Create object with OBJECT_PHYS flag and
1187 * assume min_count 0.
1189 create_object_phys((unsigned long)phys
, size
, 0, gfp
);
1191 EXPORT_SYMBOL(kmemleak_alloc_phys
);
1194 * kmemleak_free_part_phys - similar to kmemleak_free_part but taking a
1195 * physical address argument
1196 * @phys: physical address if the beginning or inside an object. This
1197 * also represents the start of the range to be freed
1198 * @size: size to be unregistered
1200 void __ref
kmemleak_free_part_phys(phys_addr_t phys
, size_t size
)
1202 pr_debug("%s(0x%pa)\n", __func__
, &phys
);
1204 if (kmemleak_enabled
)
1205 delete_object_part((unsigned long)phys
, size
, true);
1207 EXPORT_SYMBOL(kmemleak_free_part_phys
);
1210 * kmemleak_ignore_phys - similar to kmemleak_ignore but taking a physical
1212 * @phys: physical address of the object
1214 void __ref
kmemleak_ignore_phys(phys_addr_t phys
)
1216 pr_debug("%s(0x%pa)\n", __func__
, &phys
);
1218 if (kmemleak_enabled
)
1219 make_black_object((unsigned long)phys
, true);
1221 EXPORT_SYMBOL(kmemleak_ignore_phys
);
1224 * Update an object's checksum and return true if it was modified.
1226 static bool update_checksum(struct kmemleak_object
*object
)
1228 u32 old_csum
= object
->checksum
;
1230 if (WARN_ON_ONCE(object
->flags
& OBJECT_PHYS
))
1233 kasan_disable_current();
1234 kcsan_disable_current();
1235 object
->checksum
= crc32(0, kasan_reset_tag((void *)object
->pointer
), object
->size
);
1236 kasan_enable_current();
1237 kcsan_enable_current();
1239 return object
->checksum
!= old_csum
;
1243 * Update an object's references. object->lock must be held by the caller.
1245 static void update_refs(struct kmemleak_object
*object
)
1247 if (!color_white(object
)) {
1248 /* non-orphan, ignored or new */
1253 * Increase the object's reference count (number of pointers to the
1254 * memory block). If this count reaches the required minimum, the
1255 * object's color will become gray and it will be added to the
1259 if (color_gray(object
)) {
1260 /* put_object() called when removing from gray_list */
1261 WARN_ON(!get_object(object
));
1262 list_add_tail(&object
->gray_list
, &gray_list
);
1267 * Memory scanning is a long process and it needs to be interruptible. This
1268 * function checks whether such interrupt condition occurred.
1270 static int scan_should_stop(void)
1272 if (!kmemleak_enabled
)
1276 * This function may be called from either process or kthread context,
1277 * hence the need to check for both stop conditions.
1280 return signal_pending(current
);
1282 return kthread_should_stop();
1288 * Scan a memory block (exclusive range) for valid pointers and add those
1289 * found to the gray list.
1291 static void scan_block(void *_start
, void *_end
,
1292 struct kmemleak_object
*scanned
)
1295 unsigned long *start
= PTR_ALIGN(_start
, BYTES_PER_POINTER
);
1296 unsigned long *end
= _end
- (BYTES_PER_POINTER
- 1);
1297 unsigned long flags
;
1298 unsigned long untagged_ptr
;
1300 raw_spin_lock_irqsave(&kmemleak_lock
, flags
);
1301 for (ptr
= start
; ptr
< end
; ptr
++) {
1302 struct kmemleak_object
*object
;
1303 unsigned long pointer
;
1304 unsigned long excess_ref
;
1306 if (scan_should_stop())
1309 kasan_disable_current();
1310 pointer
= *(unsigned long *)kasan_reset_tag((void *)ptr
);
1311 kasan_enable_current();
1313 untagged_ptr
= (unsigned long)kasan_reset_tag((void *)pointer
);
1314 if (untagged_ptr
< min_addr
|| untagged_ptr
>= max_addr
)
1318 * No need for get_object() here since we hold kmemleak_lock.
1319 * object->use_count cannot be dropped to 0 while the object
1320 * is still present in object_tree_root and object_list
1321 * (with updates protected by kmemleak_lock).
1323 object
= lookup_object(pointer
, 1);
1326 if (object
== scanned
)
1327 /* self referenced, ignore */
1331 * Avoid the lockdep recursive warning on object->lock being
1332 * previously acquired in scan_object(). These locks are
1333 * enclosed by scan_mutex.
1335 raw_spin_lock_nested(&object
->lock
, SINGLE_DEPTH_NESTING
);
1336 /* only pass surplus references (object already gray) */
1337 if (color_gray(object
)) {
1338 excess_ref
= object
->excess_ref
;
1339 /* no need for update_refs() if object already gray */
1342 update_refs(object
);
1344 raw_spin_unlock(&object
->lock
);
1347 object
= lookup_object(excess_ref
, 0);
1350 if (object
== scanned
)
1351 /* circular reference, ignore */
1353 raw_spin_lock_nested(&object
->lock
, SINGLE_DEPTH_NESTING
);
1354 update_refs(object
);
1355 raw_spin_unlock(&object
->lock
);
1358 raw_spin_unlock_irqrestore(&kmemleak_lock
, flags
);
1362 * Scan a large memory block in MAX_SCAN_SIZE chunks to reduce the latency.
1365 static void scan_large_block(void *start
, void *end
)
1369 while (start
< end
) {
1370 next
= min(start
+ MAX_SCAN_SIZE
, end
);
1371 scan_block(start
, next
, NULL
);
1379 * Scan a memory block corresponding to a kmemleak_object. A condition is
1380 * that object->use_count >= 1.
1382 static void scan_object(struct kmemleak_object
*object
)
1384 struct kmemleak_scan_area
*area
;
1385 unsigned long flags
;
1389 * Once the object->lock is acquired, the corresponding memory block
1390 * cannot be freed (the same lock is acquired in delete_object).
1392 raw_spin_lock_irqsave(&object
->lock
, flags
);
1393 if (object
->flags
& OBJECT_NO_SCAN
)
1395 if (!(object
->flags
& OBJECT_ALLOCATED
))
1396 /* already freed object */
1399 obj_ptr
= object
->flags
& OBJECT_PHYS
?
1400 __va((phys_addr_t
)object
->pointer
) :
1401 (void *)object
->pointer
;
1403 if (hlist_empty(&object
->area_list
) ||
1404 object
->flags
& OBJECT_FULL_SCAN
) {
1405 void *start
= obj_ptr
;
1406 void *end
= obj_ptr
+ object
->size
;
1410 next
= min(start
+ MAX_SCAN_SIZE
, end
);
1411 scan_block(start
, next
, object
);
1417 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1419 raw_spin_lock_irqsave(&object
->lock
, flags
);
1420 } while (object
->flags
& OBJECT_ALLOCATED
);
1422 hlist_for_each_entry(area
, &object
->area_list
, node
)
1423 scan_block((void *)area
->start
,
1424 (void *)(area
->start
+ area
->size
),
1427 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1431 * Scan the objects already referenced (gray objects). More objects will be
1432 * referenced and, if there are no memory leaks, all the objects are scanned.
1434 static void scan_gray_list(void)
1436 struct kmemleak_object
*object
, *tmp
;
1439 * The list traversal is safe for both tail additions and removals
1440 * from inside the loop. The kmemleak objects cannot be freed from
1441 * outside the loop because their use_count was incremented.
1443 object
= list_entry(gray_list
.next
, typeof(*object
), gray_list
);
1444 while (&object
->gray_list
!= &gray_list
) {
1447 /* may add new objects to the list */
1448 if (!scan_should_stop())
1449 scan_object(object
);
1451 tmp
= list_entry(object
->gray_list
.next
, typeof(*object
),
1454 /* remove the object from the list and release it */
1455 list_del(&object
->gray_list
);
1460 WARN_ON(!list_empty(&gray_list
));
1464 * Conditionally call resched() in a object iteration loop while making sure
1465 * that the given object won't go away without RCU read lock by performing a
1466 * get_object() if !pinned.
1468 * Return: false if can't do a cond_resched() due to get_object() failure
1471 static bool kmemleak_cond_resched(struct kmemleak_object
*object
, bool pinned
)
1473 if (!pinned
&& !get_object(object
))
1485 * Scan data sections and all the referenced memory blocks allocated via the
1486 * kernel's standard allocators. This function must be called with the
1489 static void kmemleak_scan(void)
1491 struct kmemleak_object
*object
;
1493 int __maybe_unused i
;
1497 jiffies_last_scan
= jiffies
;
1499 /* prepare the kmemleak_object's */
1501 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1502 bool obj_pinned
= false;
1504 raw_spin_lock_irq(&object
->lock
);
1507 * With a few exceptions there should be a maximum of
1508 * 1 reference to any object at this point.
1510 if (atomic_read(&object
->use_count
) > 1) {
1511 pr_debug("object->use_count = %d\n",
1512 atomic_read(&object
->use_count
));
1513 dump_object_info(object
);
1517 /* ignore objects outside lowmem (paint them black) */
1518 if ((object
->flags
& OBJECT_PHYS
) &&
1519 !(object
->flags
& OBJECT_NO_SCAN
)) {
1520 unsigned long phys
= object
->pointer
;
1522 if (PHYS_PFN(phys
) < min_low_pfn
||
1523 PHYS_PFN(phys
+ object
->size
) >= max_low_pfn
)
1524 __paint_it(object
, KMEMLEAK_BLACK
);
1527 /* reset the reference count (whiten the object) */
1529 if (color_gray(object
) && get_object(object
)) {
1530 list_add_tail(&object
->gray_list
, &gray_list
);
1534 raw_spin_unlock_irq(&object
->lock
);
1537 * Do a cond_resched() every 64k objects to avoid soft lockup.
1539 if (!(++loop_cnt
& 0xffff) &&
1540 !kmemleak_cond_resched(object
, obj_pinned
))
1541 loop_cnt
--; /* Try again on next object */
1546 /* per-cpu sections scanning */
1547 for_each_possible_cpu(i
)
1548 scan_large_block(__per_cpu_start
+ per_cpu_offset(i
),
1549 __per_cpu_end
+ per_cpu_offset(i
));
1553 * Struct page scanning for each node.
1556 for_each_populated_zone(zone
) {
1557 unsigned long start_pfn
= zone
->zone_start_pfn
;
1558 unsigned long end_pfn
= zone_end_pfn(zone
);
1561 for (pfn
= start_pfn
; pfn
< end_pfn
; pfn
++) {
1562 struct page
*page
= pfn_to_online_page(pfn
);
1567 /* only scan pages belonging to this zone */
1568 if (page_zone(page
) != zone
)
1570 /* only scan if page is in use */
1571 if (page_count(page
) == 0)
1573 scan_block(page
, page
+ 1, NULL
);
1581 * Scanning the task stacks (may introduce false negatives).
1583 if (kmemleak_stack_scan
) {
1584 struct task_struct
*p
, *g
;
1587 for_each_process_thread(g
, p
) {
1588 void *stack
= try_get_task_stack(p
);
1590 scan_block(stack
, stack
+ THREAD_SIZE
, NULL
);
1598 * Scan the objects already referenced from the sections scanned
1604 * Check for new or unreferenced objects modified since the previous
1605 * scan and color them gray until the next scan.
1609 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1611 * Do a cond_resched() every 64k objects to avoid soft lockup.
1613 if (!(++loop_cnt
& 0xffff) &&
1614 !kmemleak_cond_resched(object
, false))
1615 loop_cnt
--; /* Try again on next object */
1618 * This is racy but we can save the overhead of lock/unlock
1619 * calls. The missed objects, if any, should be caught in
1622 if (!color_white(object
))
1624 raw_spin_lock_irq(&object
->lock
);
1625 if (color_white(object
) && (object
->flags
& OBJECT_ALLOCATED
)
1626 && update_checksum(object
) && get_object(object
)) {
1627 /* color it gray temporarily */
1628 object
->count
= object
->min_count
;
1629 list_add_tail(&object
->gray_list
, &gray_list
);
1631 raw_spin_unlock_irq(&object
->lock
);
1636 * Re-scan the gray list for modified unreferenced objects.
1641 * If scanning was stopped do not report any new unreferenced objects.
1643 if (scan_should_stop())
1647 * Scanning result reporting.
1651 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1653 * Do a cond_resched() every 64k objects to avoid soft lockup.
1655 if (!(++loop_cnt
& 0xffff) &&
1656 !kmemleak_cond_resched(object
, false))
1657 loop_cnt
--; /* Try again on next object */
1660 * This is racy but we can save the overhead of lock/unlock
1661 * calls. The missed objects, if any, should be caught in
1664 if (!color_white(object
))
1666 raw_spin_lock_irq(&object
->lock
);
1667 if (unreferenced_object(object
) &&
1668 !(object
->flags
& OBJECT_REPORTED
)) {
1669 object
->flags
|= OBJECT_REPORTED
;
1671 if (kmemleak_verbose
)
1672 print_unreferenced(NULL
, object
);
1676 raw_spin_unlock_irq(&object
->lock
);
1681 kmemleak_found_leaks
= true;
1683 pr_info("%d new suspected memory leaks (see /sys/kernel/debug/kmemleak)\n",
1690 * Thread function performing automatic memory scanning. Unreferenced objects
1691 * at the end of a memory scan are reported but only the first time.
1693 static int kmemleak_scan_thread(void *arg
)
1695 static int first_run
= IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN
);
1697 pr_info("Automatic memory scanning thread started\n");
1698 set_user_nice(current
, 10);
1701 * Wait before the first scan to allow the system to fully initialize.
1704 signed long timeout
= msecs_to_jiffies(SECS_FIRST_SCAN
* 1000);
1706 while (timeout
&& !kthread_should_stop())
1707 timeout
= schedule_timeout_interruptible(timeout
);
1710 while (!kthread_should_stop()) {
1711 signed long timeout
= READ_ONCE(jiffies_scan_wait
);
1713 mutex_lock(&scan_mutex
);
1715 mutex_unlock(&scan_mutex
);
1717 /* wait before the next scan */
1718 while (timeout
&& !kthread_should_stop())
1719 timeout
= schedule_timeout_interruptible(timeout
);
1722 pr_info("Automatic memory scanning thread ended\n");
1728 * Start the automatic memory scanning thread. This function must be called
1729 * with the scan_mutex held.
1731 static void start_scan_thread(void)
1735 scan_thread
= kthread_run(kmemleak_scan_thread
, NULL
, "kmemleak");
1736 if (IS_ERR(scan_thread
)) {
1737 pr_warn("Failed to create the scan thread\n");
1743 * Stop the automatic memory scanning thread.
1745 static void stop_scan_thread(void)
1748 kthread_stop(scan_thread
);
1754 * Iterate over the object_list and return the first valid object at or after
1755 * the required position with its use_count incremented. The function triggers
1756 * a memory scanning when the pos argument points to the first position.
1758 static void *kmemleak_seq_start(struct seq_file
*seq
, loff_t
*pos
)
1760 struct kmemleak_object
*object
;
1764 err
= mutex_lock_interruptible(&scan_mutex
);
1766 return ERR_PTR(err
);
1769 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1772 if (get_object(object
))
1781 * Return the next object in the object_list. The function decrements the
1782 * use_count of the previous object and increases that of the next one.
1784 static void *kmemleak_seq_next(struct seq_file
*seq
, void *v
, loff_t
*pos
)
1786 struct kmemleak_object
*prev_obj
= v
;
1787 struct kmemleak_object
*next_obj
= NULL
;
1788 struct kmemleak_object
*obj
= prev_obj
;
1792 list_for_each_entry_continue_rcu(obj
, &object_list
, object_list
) {
1793 if (get_object(obj
)) {
1799 put_object(prev_obj
);
1804 * Decrement the use_count of the last object required, if any.
1806 static void kmemleak_seq_stop(struct seq_file
*seq
, void *v
)
1810 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1811 * waiting was interrupted, so only release it if !IS_ERR.
1814 mutex_unlock(&scan_mutex
);
1821 * Print the information for an unreferenced object to the seq file.
1823 static int kmemleak_seq_show(struct seq_file
*seq
, void *v
)
1825 struct kmemleak_object
*object
= v
;
1826 unsigned long flags
;
1828 raw_spin_lock_irqsave(&object
->lock
, flags
);
1829 if ((object
->flags
& OBJECT_REPORTED
) && unreferenced_object(object
))
1830 print_unreferenced(seq
, object
);
1831 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1835 static const struct seq_operations kmemleak_seq_ops
= {
1836 .start
= kmemleak_seq_start
,
1837 .next
= kmemleak_seq_next
,
1838 .stop
= kmemleak_seq_stop
,
1839 .show
= kmemleak_seq_show
,
1842 static int kmemleak_open(struct inode
*inode
, struct file
*file
)
1844 return seq_open(file
, &kmemleak_seq_ops
);
1847 static int dump_str_object_info(const char *str
)
1849 unsigned long flags
;
1850 struct kmemleak_object
*object
;
1853 if (kstrtoul(str
, 0, &addr
))
1855 object
= find_and_get_object(addr
, 0);
1857 pr_info("Unknown object at 0x%08lx\n", addr
);
1861 raw_spin_lock_irqsave(&object
->lock
, flags
);
1862 dump_object_info(object
);
1863 raw_spin_unlock_irqrestore(&object
->lock
, flags
);
1870 * We use grey instead of black to ensure we can do future scans on the same
1871 * objects. If we did not do future scans these black objects could
1872 * potentially contain references to newly allocated objects in the future and
1873 * we'd end up with false positives.
1875 static void kmemleak_clear(void)
1877 struct kmemleak_object
*object
;
1880 list_for_each_entry_rcu(object
, &object_list
, object_list
) {
1881 raw_spin_lock_irq(&object
->lock
);
1882 if ((object
->flags
& OBJECT_REPORTED
) &&
1883 unreferenced_object(object
))
1884 __paint_it(object
, KMEMLEAK_GREY
);
1885 raw_spin_unlock_irq(&object
->lock
);
1889 kmemleak_found_leaks
= false;
1892 static void __kmemleak_do_cleanup(void);
1895 * File write operation to configure kmemleak at run-time. The following
1896 * commands can be written to the /sys/kernel/debug/kmemleak file:
1897 * off - disable kmemleak (irreversible)
1898 * stack=on - enable the task stacks scanning
1899 * stack=off - disable the tasks stacks scanning
1900 * scan=on - start the automatic memory scanning thread
1901 * scan=off - stop the automatic memory scanning thread
1902 * scan=... - set the automatic memory scanning period in seconds (0 to
1904 * scan - trigger a memory scan
1905 * clear - mark all current reported unreferenced kmemleak objects as
1906 * grey to ignore printing them, or free all kmemleak objects
1907 * if kmemleak has been disabled.
1908 * dump=... - dump information about the object found at the given address
1910 static ssize_t
kmemleak_write(struct file
*file
, const char __user
*user_buf
,
1911 size_t size
, loff_t
*ppos
)
1917 buf_size
= min(size
, (sizeof(buf
) - 1));
1918 if (strncpy_from_user(buf
, user_buf
, buf_size
) < 0)
1922 ret
= mutex_lock_interruptible(&scan_mutex
);
1926 if (strncmp(buf
, "clear", 5) == 0) {
1927 if (kmemleak_enabled
)
1930 __kmemleak_do_cleanup();
1934 if (!kmemleak_enabled
) {
1939 if (strncmp(buf
, "off", 3) == 0)
1941 else if (strncmp(buf
, "stack=on", 8) == 0)
1942 kmemleak_stack_scan
= 1;
1943 else if (strncmp(buf
, "stack=off", 9) == 0)
1944 kmemleak_stack_scan
= 0;
1945 else if (strncmp(buf
, "scan=on", 7) == 0)
1946 start_scan_thread();
1947 else if (strncmp(buf
, "scan=off", 8) == 0)
1949 else if (strncmp(buf
, "scan=", 5) == 0) {
1951 unsigned long msecs
;
1953 ret
= kstrtouint(buf
+ 5, 0, &secs
);
1957 msecs
= secs
* MSEC_PER_SEC
;
1958 if (msecs
> UINT_MAX
)
1963 WRITE_ONCE(jiffies_scan_wait
, msecs_to_jiffies(msecs
));
1964 start_scan_thread();
1966 } else if (strncmp(buf
, "scan", 4) == 0)
1968 else if (strncmp(buf
, "dump=", 5) == 0)
1969 ret
= dump_str_object_info(buf
+ 5);
1974 mutex_unlock(&scan_mutex
);
1978 /* ignore the rest of the buffer, only one command at a time */
1983 static const struct file_operations kmemleak_fops
= {
1984 .owner
= THIS_MODULE
,
1985 .open
= kmemleak_open
,
1987 .write
= kmemleak_write
,
1988 .llseek
= seq_lseek
,
1989 .release
= seq_release
,
1992 static void __kmemleak_do_cleanup(void)
1994 struct kmemleak_object
*object
, *tmp
;
1997 * Kmemleak has already been disabled, no need for RCU list traversal
1998 * or kmemleak_lock held.
2000 list_for_each_entry_safe(object
, tmp
, &object_list
, object_list
) {
2001 __remove_object(object
);
2002 __delete_object(object
);
2007 * Stop the memory scanning thread and free the kmemleak internal objects if
2008 * no previous scan thread (otherwise, kmemleak may still have some useful
2009 * information on memory leaks).
2011 static void kmemleak_do_cleanup(struct work_struct
*work
)
2015 mutex_lock(&scan_mutex
);
2017 * Once it is made sure that kmemleak_scan has stopped, it is safe to no
2018 * longer track object freeing. Ordering of the scan thread stopping and
2019 * the memory accesses below is guaranteed by the kthread_stop()
2022 kmemleak_free_enabled
= 0;
2023 mutex_unlock(&scan_mutex
);
2025 if (!kmemleak_found_leaks
)
2026 __kmemleak_do_cleanup();
2028 pr_info("Kmemleak disabled without freeing internal data. Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\".\n");
2031 static DECLARE_WORK(cleanup_work
, kmemleak_do_cleanup
);
2034 * Disable kmemleak. No memory allocation/freeing will be traced once this
2035 * function is called. Disabling kmemleak is an irreversible operation.
2037 static void kmemleak_disable(void)
2039 /* atomically check whether it was already invoked */
2040 if (cmpxchg(&kmemleak_error
, 0, 1))
2043 /* stop any memory operation tracing */
2044 kmemleak_enabled
= 0;
2046 /* check whether it is too early for a kernel thread */
2047 if (kmemleak_initialized
)
2048 schedule_work(&cleanup_work
);
2050 kmemleak_free_enabled
= 0;
2052 pr_info("Kernel memory leak detector disabled\n");
2056 * Allow boot-time kmemleak disabling (enabled by default).
2058 static int __init
kmemleak_boot_config(char *str
)
2062 if (strcmp(str
, "off") == 0)
2064 else if (strcmp(str
, "on") == 0)
2065 kmemleak_skip_disable
= 1;
2070 early_param("kmemleak", kmemleak_boot_config
);
2073 * Kmemleak initialization.
2075 void __init
kmemleak_init(void)
2077 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
2078 if (!kmemleak_skip_disable
) {
2087 jiffies_min_age
= msecs_to_jiffies(MSECS_MIN_AGE
);
2088 jiffies_scan_wait
= msecs_to_jiffies(SECS_SCAN_WAIT
* 1000);
2090 object_cache
= KMEM_CACHE(kmemleak_object
, SLAB_NOLEAKTRACE
);
2091 scan_area_cache
= KMEM_CACHE(kmemleak_scan_area
, SLAB_NOLEAKTRACE
);
2093 /* register the data/bss sections */
2094 create_object((unsigned long)_sdata
, _edata
- _sdata
,
2095 KMEMLEAK_GREY
, GFP_ATOMIC
);
2096 create_object((unsigned long)__bss_start
, __bss_stop
- __bss_start
,
2097 KMEMLEAK_GREY
, GFP_ATOMIC
);
2098 /* only register .data..ro_after_init if not within .data */
2099 if (&__start_ro_after_init
< &_sdata
|| &__end_ro_after_init
> &_edata
)
2100 create_object((unsigned long)__start_ro_after_init
,
2101 __end_ro_after_init
- __start_ro_after_init
,
2102 KMEMLEAK_GREY
, GFP_ATOMIC
);
2106 * Late initialization function.
2108 static int __init
kmemleak_late_init(void)
2110 kmemleak_initialized
= 1;
2112 debugfs_create_file("kmemleak", 0644, NULL
, NULL
, &kmemleak_fops
);
2114 if (kmemleak_error
) {
2116 * Some error occurred and kmemleak was disabled. There is a
2117 * small chance that kmemleak_disable() was called immediately
2118 * after setting kmemleak_initialized and we may end up with
2119 * two clean-up threads but serialized by scan_mutex.
2121 schedule_work(&cleanup_work
);
2125 if (IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN
)) {
2126 mutex_lock(&scan_mutex
);
2127 start_scan_thread();
2128 mutex_unlock(&scan_mutex
);
2131 pr_info("Kernel memory leak detector initialized (mem pool available: %d)\n",
2132 mem_pool_free_count
);
2136 late_initcall(kmemleak_late_init
);