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_tree_root (or
18 * object_phys_tree_root). The object_list is the main list holding the
19 * metadata (struct kmemleak_object) for the allocated memory blocks.
20 * The object_tree_root and object_phys_tree_root are red
21 * black trees used to look-up metadata based on a pointer to the
22 * corresponding memory block. The object_phys_tree_root is for objects
23 * allocated with physical address. The kmemleak_object structures are
24 * added to the object_list and object_tree_root (or object_phys_tree_root)
25 * in the create_object() function called from the kmemleak_alloc() (or
26 * kmemleak_alloc_phys()) callback and removed in delete_object() called from
27 * the kmemleak_free() callback
28 * - kmemleak_object.lock (raw_spinlock_t): protects a kmemleak_object.
29 * Accesses to the metadata (e.g. count) are protected by this lock. Note
30 * that some members of this structure may be protected by other means
31 * (atomic or kmemleak_lock). This lock is also held when scanning the
32 * corresponding memory block to avoid the kernel freeing it via the
33 * kmemleak_free() callback. This is less heavyweight than holding a global
34 * lock like kmemleak_lock during scanning.
35 * - scan_mutex (mutex): ensures that only one thread may scan the memory for
36 * unreferenced objects at a time. The gray_list contains the objects which
37 * are already referenced or marked as false positives and need to be
38 * scanned. This list is only modified during a scanning episode when the
39 * scan_mutex is held. At the end of a scan, the gray_list is always empty.
40 * Note that the kmemleak_object.use_count is incremented when an object is
41 * added to the gray_list and therefore cannot be freed. This mutex also
42 * prevents multiple users of the "kmemleak" debugfs file together with
43 * modifications to the memory scanning parameters including the scan_thread
46 * Locks and mutexes are acquired/nested in the following order:
48 * scan_mutex [-> object->lock] -> kmemleak_lock -> other_object->lock (SINGLE_DEPTH_NESTING)
50 * No kmemleak_lock and object->lock nesting is allowed outside scan_mutex
53 * The kmemleak_object structures have a use_count incremented or decremented
54 * using the get_object()/put_object() functions. When the use_count becomes
55 * 0, this count can no longer be incremented and put_object() schedules the
56 * kmemleak_object freeing via an RCU callback. All calls to the get_object()
57 * function must be protected by rcu_read_lock() to avoid accessing a freed
61 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
63 #include <linux/init.h>
64 #include <linux/kernel.h>
65 #include <linux/list.h>
66 #include <linux/sched/signal.h>
67 #include <linux/sched/task.h>
68 #include <linux/sched/task_stack.h>
69 #include <linux/jiffies.h>
70 #include <linux/delay.h>
71 #include <linux/export.h>
72 #include <linux/kthread.h>
73 #include <linux/rbtree.h>
75 #include <linux/debugfs.h>
76 #include <linux/seq_file.h>
77 #include <linux/cpumask.h>
78 #include <linux/spinlock.h>
79 #include <linux/module.h>
80 #include <linux/mutex.h>
81 #include <linux/rcupdate.h>
82 #include <linux/stacktrace.h>
83 #include <linux/stackdepot.h>
84 #include <linux/cache.h>
85 #include <linux/percpu.h>
86 #include <linux/memblock.h>
87 #include <linux/pfn.h>
88 #include <linux/mmzone.h>
89 #include <linux/slab.h>
90 #include <linux/thread_info.h>
91 #include <linux/err.h>
92 #include <linux/uaccess.h>
93 #include <linux/string.h>
94 #include <linux/nodemask.h>
96 #include <linux/workqueue.h>
97 #include <linux/crc32.h>
99 #include <asm/sections.h>
100 #include <asm/processor.h>
101 #include <linux/atomic.h>
103 #include <linux/kasan.h>
104 #include <linux/kfence.h>
105 #include <linux/kmemleak.h>
106 #include <linux/memory_hotplug.h>
109 * Kmemleak configuration and common defines.
111 #define MAX_TRACE 16 /* stack trace length */
112 #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
113 #define SECS_FIRST_SCAN 60 /* delay before the first scan */
114 #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
115 #define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
117 #define BYTES_PER_POINTER sizeof(void *)
119 /* GFP bitmask for kmemleak internal allocations */
120 #define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC | \
121 __GFP_NOLOCKDEP)) | \
122 __GFP_NORETRY | __GFP_NOMEMALLOC | \
125 /* scanning area inside a memory block */
126 struct kmemleak_scan_area {
127 struct hlist_node node;
132 #define KMEMLEAK_GREY 0
133 #define KMEMLEAK_BLACK -1
136 * Structure holding the metadata for each allocated memory block.
137 * Modifications to such objects should be made while holding the
138 * object->lock. Insertions or deletions from object_list, gray_list or
139 * rb_node are already protected by the corresponding locks or mutex (see
140 * the notes on locking above). These objects are reference-counted
141 * (use_count) and freed using the RCU mechanism.
143 struct kmemleak_object {
145 unsigned int flags; /* object status flags */
146 struct list_head object_list;
147 struct list_head gray_list;
148 struct rb_node rb_node;
149 struct rcu_head rcu; /* object_list lockless traversal */
150 /* object usage count; object freed when use_count == 0 */
152 unsigned int del_state; /* deletion state */
153 unsigned long pointer;
155 /* pass surplus references to this pointer */
156 unsigned long excess_ref;
157 /* minimum number of a pointers found before it is considered leak */
159 /* the total number of pointers found pointing to this object */
161 /* checksum for detecting modified objects */
163 /* memory ranges to be scanned inside an object (empty for all) */
164 struct hlist_head area_list;
165 depot_stack_handle_t trace_handle;
166 unsigned long jiffies; /* creation timestamp */
167 pid_t pid; /* pid of the current task */
168 char comm[TASK_COMM_LEN]; /* executable name */
171 /* flag representing the memory block allocation status */
172 #define OBJECT_ALLOCATED (1 << 0)
173 /* flag set after the first reporting of an unreference object */
174 #define OBJECT_REPORTED (1 << 1)
175 /* flag set to not scan the object */
176 #define OBJECT_NO_SCAN (1 << 2)
177 /* flag set to fully scan the object when scan_area allocation failed */
178 #define OBJECT_FULL_SCAN (1 << 3)
179 /* flag set for object allocated with physical address */
180 #define OBJECT_PHYS (1 << 4)
182 /* set when __remove_object() called */
183 #define DELSTATE_REMOVED (1 << 0)
184 /* set to temporarily prevent deletion from object_list */
185 #define DELSTATE_NO_DELETE (1 << 1)
187 #define HEX_PREFIX " "
188 /* number of bytes to print per line; must be 16 or 32 */
189 #define HEX_ROW_SIZE 16
190 /* number of bytes to print at a time (1, 2, 4, 8) */
191 #define HEX_GROUP_SIZE 1
192 /* include ASCII after the hex output */
194 /* max number of lines to be printed */
195 #define HEX_MAX_LINES 2
197 /* the list of all allocated objects */
198 static LIST_HEAD(object_list);
199 /* the list of gray-colored objects (see color_gray comment below) */
200 static LIST_HEAD(gray_list);
201 /* memory pool allocation */
202 static struct kmemleak_object mem_pool[CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE];
203 static int mem_pool_free_count = ARRAY_SIZE(mem_pool);
204 static LIST_HEAD(mem_pool_free_list);
205 /* search tree for object boundaries */
206 static struct rb_root object_tree_root = RB_ROOT;
207 /* search tree for object (with OBJECT_PHYS flag) boundaries */
208 static struct rb_root object_phys_tree_root = RB_ROOT;
209 /* protecting the access to object_list, object_tree_root (or object_phys_tree_root) */
210 static DEFINE_RAW_SPINLOCK(kmemleak_lock);
212 /* allocation caches for kmemleak internal data */
213 static struct kmem_cache *object_cache;
214 static struct kmem_cache *scan_area_cache;
216 /* set if tracing memory operations is enabled */
217 static int kmemleak_enabled = 1;
218 /* same as above but only for the kmemleak_free() callback */
219 static int kmemleak_free_enabled = 1;
220 /* set in the late_initcall if there were no errors */
221 static int kmemleak_late_initialized;
222 /* set if a kmemleak warning was issued */
223 static int kmemleak_warning;
224 /* set if a fatal kmemleak error has occurred */
225 static int kmemleak_error;
227 /* minimum and maximum address that may be valid pointers */
228 static unsigned long min_addr = ULONG_MAX;
229 static unsigned long max_addr;
231 static struct task_struct *scan_thread;
232 /* used to avoid reporting of recently allocated objects */
233 static unsigned long jiffies_min_age;
234 static unsigned long jiffies_last_scan;
235 /* delay between automatic memory scannings */
236 static unsigned long jiffies_scan_wait;
237 /* enables or disables the task stacks scanning */
238 static int kmemleak_stack_scan = 1;
239 /* protects the memory scanning, parameters and debug/kmemleak file access */
240 static DEFINE_MUTEX(scan_mutex);
241 /* setting kmemleak=on, will set this var, skipping the disable */
242 static int kmemleak_skip_disable;
243 /* If there are leaks that can be reported */
244 static bool kmemleak_found_leaks;
246 static bool kmemleak_verbose;
247 module_param_named(verbose, kmemleak_verbose, bool, 0600);
249 static void kmemleak_disable(void);
252 * Print a warning and dump the stack trace.
254 #define kmemleak_warn(x...) do { \
257 kmemleak_warning = 1; \
261 * Macro invoked when a serious kmemleak condition occurred and cannot be
262 * recovered from. Kmemleak will be disabled and further allocation/freeing
263 * tracing no longer available.
265 #define kmemleak_stop(x...) do { \
267 kmemleak_disable(); \
270 #define warn_or_seq_printf(seq, fmt, ...) do { \
272 seq_printf(seq, fmt, ##__VA_ARGS__); \
274 pr_warn(fmt, ##__VA_ARGS__); \
277 static void warn_or_seq_hex_dump(struct seq_file *seq, int prefix_type,
278 int rowsize, int groupsize, const void *buf,
279 size_t len, bool ascii)
282 seq_hex_dump(seq, HEX_PREFIX, prefix_type, rowsize, groupsize,
285 print_hex_dump(KERN_WARNING, pr_fmt(HEX_PREFIX), prefix_type,
286 rowsize, groupsize, buf, len, ascii);
290 * Printing of the objects hex dump to the seq file. The number of lines to be
291 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
292 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
293 * with the object->lock held.
295 static void hex_dump_object(struct seq_file *seq,
296 struct kmemleak_object *object)
298 const u8 *ptr = (const u8 *)object->pointer;
301 if (WARN_ON_ONCE(object->flags & OBJECT_PHYS))
304 /* limit the number of lines to HEX_MAX_LINES */
305 len = min_t(size_t, object->size, HEX_MAX_LINES * HEX_ROW_SIZE);
307 warn_or_seq_printf(seq, " hex dump (first %zu bytes):\n", len);
308 kasan_disable_current();
309 warn_or_seq_hex_dump(seq, DUMP_PREFIX_NONE, HEX_ROW_SIZE,
310 HEX_GROUP_SIZE, kasan_reset_tag((void *)ptr), len, HEX_ASCII);
311 kasan_enable_current();
315 * Object colors, encoded with count and min_count:
316 * - white - orphan object, not enough references to it (count < min_count)
317 * - gray - not orphan, not marked as false positive (min_count == 0) or
318 * sufficient references to it (count >= min_count)
319 * - black - ignore, it doesn't contain references (e.g. text section)
320 * (min_count == -1). No function defined for this color.
321 * Newly created objects don't have any color assigned (object->count == -1)
322 * before the next memory scan when they become white.
324 static bool color_white(const struct kmemleak_object *object)
326 return object->count != KMEMLEAK_BLACK &&
327 object->count < object->min_count;
330 static bool color_gray(const struct kmemleak_object *object)
332 return object->min_count != KMEMLEAK_BLACK &&
333 object->count >= object->min_count;
337 * Objects are considered unreferenced only if their color is white, they have
338 * not be deleted and have a minimum age to avoid false positives caused by
339 * pointers temporarily stored in CPU registers.
341 static bool unreferenced_object(struct kmemleak_object *object)
343 return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
344 time_before_eq(object->jiffies + jiffies_min_age,
349 * Printing of the unreferenced objects information to the seq file. The
350 * print_unreferenced function must be called with the object->lock held.
352 static void print_unreferenced(struct seq_file *seq,
353 struct kmemleak_object *object)
356 unsigned long *entries;
357 unsigned int nr_entries;
358 unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
360 nr_entries = stack_depot_fetch(object->trace_handle, &entries);
361 warn_or_seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
362 object->pointer, object->size);
363 warn_or_seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
364 object->comm, object->pid, object->jiffies,
365 msecs_age / 1000, msecs_age % 1000);
366 hex_dump_object(seq, object);
367 warn_or_seq_printf(seq, " backtrace:\n");
369 for (i = 0; i < nr_entries; i++) {
370 void *ptr = (void *)entries[i];
371 warn_or_seq_printf(seq, " [<%pK>] %pS\n", ptr, ptr);
376 * Print the kmemleak_object information. This function is used mainly for
377 * debugging special cases when kmemleak operations. It must be called with
378 * the object->lock held.
380 static void dump_object_info(struct kmemleak_object *object)
382 pr_notice("Object 0x%08lx (size %zu):\n",
383 object->pointer, object->size);
384 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
385 object->comm, object->pid, object->jiffies);
386 pr_notice(" min_count = %d\n", object->min_count);
387 pr_notice(" count = %d\n", object->count);
388 pr_notice(" flags = 0x%x\n", object->flags);
389 pr_notice(" checksum = %u\n", object->checksum);
390 pr_notice(" backtrace:\n");
391 if (object->trace_handle)
392 stack_depot_print(object->trace_handle);
396 * Look-up a memory block metadata (kmemleak_object) in the object search
397 * tree based on a pointer value. If alias is 0, only values pointing to the
398 * beginning of the memory block are allowed. The kmemleak_lock must be held
399 * when calling this function.
401 static struct kmemleak_object *__lookup_object(unsigned long ptr, int alias,
404 struct rb_node *rb = is_phys ? object_phys_tree_root.rb_node :
405 object_tree_root.rb_node;
406 unsigned long untagged_ptr = (unsigned long)kasan_reset_tag((void *)ptr);
409 struct kmemleak_object *object;
410 unsigned long untagged_objp;
412 object = rb_entry(rb, struct kmemleak_object, rb_node);
413 untagged_objp = (unsigned long)kasan_reset_tag((void *)object->pointer);
415 if (untagged_ptr < untagged_objp)
416 rb = object->rb_node.rb_left;
417 else if (untagged_objp + object->size <= untagged_ptr)
418 rb = object->rb_node.rb_right;
419 else if (untagged_objp == untagged_ptr || alias)
422 kmemleak_warn("Found object by alias at 0x%08lx\n",
424 dump_object_info(object);
431 /* Look-up a kmemleak object which allocated with virtual address. */
432 static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
434 return __lookup_object(ptr, alias, false);
438 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
439 * that once an object's use_count reached 0, the RCU freeing was already
440 * registered and the object should no longer be used. This function must be
441 * called under the protection of rcu_read_lock().
443 static int get_object(struct kmemleak_object *object)
445 return atomic_inc_not_zero(&object->use_count);
449 * Memory pool allocation and freeing. kmemleak_lock must not be held.
451 static struct kmemleak_object *mem_pool_alloc(gfp_t gfp)
454 struct kmemleak_object *object;
456 /* try the slab allocator first */
458 object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
463 /* slab allocation failed, try the memory pool */
464 raw_spin_lock_irqsave(&kmemleak_lock, flags);
465 object = list_first_entry_or_null(&mem_pool_free_list,
466 typeof(*object), object_list);
468 list_del(&object->object_list);
469 else if (mem_pool_free_count)
470 object = &mem_pool[--mem_pool_free_count];
472 pr_warn_once("Memory pool empty, consider increasing CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE\n");
473 raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
479 * Return the object to either the slab allocator or the memory pool.
481 static void mem_pool_free(struct kmemleak_object *object)
485 if (object < mem_pool || object >= mem_pool + ARRAY_SIZE(mem_pool)) {
486 kmem_cache_free(object_cache, object);
490 /* add the object to the memory pool free list */
491 raw_spin_lock_irqsave(&kmemleak_lock, flags);
492 list_add(&object->object_list, &mem_pool_free_list);
493 raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
497 * RCU callback to free a kmemleak_object.
499 static void free_object_rcu(struct rcu_head *rcu)
501 struct hlist_node *tmp;
502 struct kmemleak_scan_area *area;
503 struct kmemleak_object *object =
504 container_of(rcu, struct kmemleak_object, rcu);
507 * Once use_count is 0 (guaranteed by put_object), there is no other
508 * code accessing this object, hence no need for locking.
510 hlist_for_each_entry_safe(area, tmp, &object->area_list, node) {
511 hlist_del(&area->node);
512 kmem_cache_free(scan_area_cache, area);
514 mem_pool_free(object);
518 * Decrement the object use_count. Once the count is 0, free the object using
519 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
520 * delete_object() path, the delayed RCU freeing ensures that there is no
521 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
524 static void put_object(struct kmemleak_object *object)
526 if (!atomic_dec_and_test(&object->use_count))
529 /* should only get here after delete_object was called */
530 WARN_ON(object->flags & OBJECT_ALLOCATED);
533 * It may be too early for the RCU callbacks, however, there is no
534 * concurrent object_list traversal when !object_cache and all objects
535 * came from the memory pool. Free the object directly.
538 call_rcu(&object->rcu, free_object_rcu);
540 free_object_rcu(&object->rcu);
544 * Look up an object in the object search tree and increase its use_count.
546 static struct kmemleak_object *__find_and_get_object(unsigned long ptr, int alias,
550 struct kmemleak_object *object;
553 raw_spin_lock_irqsave(&kmemleak_lock, flags);
554 object = __lookup_object(ptr, alias, is_phys);
555 raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
557 /* check whether the object is still available */
558 if (object && !get_object(object))
565 /* Look up and get an object which allocated with virtual address. */
566 static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
568 return __find_and_get_object(ptr, alias, false);
572 * Remove an object from the object_tree_root (or object_phys_tree_root)
573 * and object_list. Must be called with the kmemleak_lock held _if_ kmemleak
576 static void __remove_object(struct kmemleak_object *object)
578 rb_erase(&object->rb_node, object->flags & OBJECT_PHYS ?
579 &object_phys_tree_root :
581 if (!(object->del_state & DELSTATE_NO_DELETE))
582 list_del_rcu(&object->object_list);
583 object->del_state |= DELSTATE_REMOVED;
587 * Look up an object in the object search tree and remove it from both
588 * object_tree_root (or object_phys_tree_root) and object_list. The
589 * returned object's use_count should be at least 1, as initially set
590 * by create_object().
592 static struct kmemleak_object *find_and_remove_object(unsigned long ptr, int alias,
596 struct kmemleak_object *object;
598 raw_spin_lock_irqsave(&kmemleak_lock, flags);
599 object = __lookup_object(ptr, alias, is_phys);
601 __remove_object(object);
602 raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
607 static noinline depot_stack_handle_t set_track_prepare(void)
609 depot_stack_handle_t trace_handle;
610 unsigned long entries[MAX_TRACE];
611 unsigned int nr_entries;
614 * Use object_cache to determine whether kmemleak_init() has
615 * been invoked. stack_depot_early_init() is called before
616 * kmemleak_init() in mm_core_init().
620 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 3);
621 trace_handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT);
627 * Create the metadata (struct kmemleak_object) corresponding to an allocated
628 * memory block and add it to the object_list and object_tree_root (or
629 * object_phys_tree_root).
631 static void __create_object(unsigned long ptr, size_t size,
632 int min_count, gfp_t gfp, bool is_phys)
635 struct kmemleak_object *object, *parent;
636 struct rb_node **link, *rb_parent;
637 unsigned long untagged_ptr;
638 unsigned long untagged_objp;
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->flags = OBJECT_ALLOCATED | (is_phys ? OBJECT_PHYS : 0);
653 object->pointer = ptr;
654 object->size = kfence_ksize((void *)ptr) ?: size;
655 object->excess_ref = 0;
656 object->min_count = min_count;
657 object->count = 0; /* white color initially */
658 object->jiffies = jiffies;
659 object->checksum = 0;
660 object->del_state = 0;
662 /* task information */
665 strncpy(object->comm, "hardirq", sizeof(object->comm));
666 } else if (in_serving_softirq()) {
668 strncpy(object->comm, "softirq", sizeof(object->comm));
670 object->pid = current->pid;
672 * There is a small chance of a race with set_task_comm(),
673 * however using get_task_comm() here may cause locking
674 * dependency issues with current->alloc_lock. In the worst
675 * case, the command line is not correct.
677 strncpy(object->comm, current->comm, sizeof(object->comm));
680 /* kernel backtrace */
681 object->trace_handle = set_track_prepare();
683 raw_spin_lock_irqsave(&kmemleak_lock, flags);
685 untagged_ptr = (unsigned long)kasan_reset_tag((void *)ptr);
687 * Only update min_addr and max_addr with object
688 * storing virtual address.
691 min_addr = min(min_addr, untagged_ptr);
692 max_addr = max(max_addr, untagged_ptr + size);
694 link = is_phys ? &object_phys_tree_root.rb_node :
695 &object_tree_root.rb_node;
699 parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
700 untagged_objp = (unsigned long)kasan_reset_tag((void *)parent->pointer);
701 if (untagged_ptr + size <= untagged_objp)
702 link = &parent->rb_node.rb_left;
703 else if (untagged_objp + parent->size <= untagged_ptr)
704 link = &parent->rb_node.rb_right;
706 kmemleak_stop("Cannot insert 0x%lx into the object search tree (overlaps existing)\n",
709 * No need for parent->lock here since "parent" cannot
710 * be freed while the kmemleak_lock is held.
712 dump_object_info(parent);
713 kmem_cache_free(object_cache, object);
717 rb_link_node(&object->rb_node, rb_parent, link);
718 rb_insert_color(&object->rb_node, is_phys ? &object_phys_tree_root :
720 list_add_tail_rcu(&object->object_list, &object_list);
722 raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
725 /* Create kmemleak object which allocated with virtual address. */
726 static void create_object(unsigned long ptr, size_t size,
727 int min_count, gfp_t gfp)
729 __create_object(ptr, size, min_count, gfp, false);
732 /* Create kmemleak object which allocated with physical address. */
733 static void create_object_phys(unsigned long ptr, size_t size,
734 int min_count, gfp_t gfp)
736 __create_object(ptr, size, min_count, gfp, true);
740 * Mark the object as not allocated and schedule RCU freeing via put_object().
742 static void __delete_object(struct kmemleak_object *object)
746 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
747 WARN_ON(atomic_read(&object->use_count) < 1);
750 * Locking here also ensures that the corresponding memory block
751 * cannot be freed when it is being scanned.
753 raw_spin_lock_irqsave(&object->lock, flags);
754 object->flags &= ~OBJECT_ALLOCATED;
755 raw_spin_unlock_irqrestore(&object->lock, flags);
760 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
763 static void delete_object_full(unsigned long ptr)
765 struct kmemleak_object *object;
767 object = find_and_remove_object(ptr, 0, false);
770 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
775 __delete_object(object);
779 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
780 * delete it. If the memory block is partially freed, the function may create
781 * additional metadata for the remaining parts of the block.
783 static void delete_object_part(unsigned long ptr, size_t size, bool is_phys)
785 struct kmemleak_object *object;
786 unsigned long start, end;
788 object = find_and_remove_object(ptr, 1, is_phys);
791 kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n",
798 * Create one or two objects that may result from the memory block
799 * split. Note that partial freeing is only done by free_bootmem() and
800 * this happens before kmemleak_init() is called.
802 start = object->pointer;
803 end = object->pointer + object->size;
805 __create_object(start, ptr - start, object->min_count,
806 GFP_KERNEL, is_phys);
807 if (ptr + size < end)
808 __create_object(ptr + size, end - ptr - size, object->min_count,
809 GFP_KERNEL, is_phys);
811 __delete_object(object);
814 static void __paint_it(struct kmemleak_object *object, int color)
816 object->min_count = color;
817 if (color == KMEMLEAK_BLACK)
818 object->flags |= OBJECT_NO_SCAN;
821 static void paint_it(struct kmemleak_object *object, int color)
825 raw_spin_lock_irqsave(&object->lock, flags);
826 __paint_it(object, color);
827 raw_spin_unlock_irqrestore(&object->lock, flags);
830 static void paint_ptr(unsigned long ptr, int color, bool is_phys)
832 struct kmemleak_object *object;
834 object = __find_and_get_object(ptr, 0, is_phys);
836 kmemleak_warn("Trying to color unknown object at 0x%08lx as %s\n",
838 (color == KMEMLEAK_GREY) ? "Grey" :
839 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
842 paint_it(object, color);
847 * Mark an object permanently as gray-colored so that it can no longer be
848 * reported as a leak. This is used in general to mark a false positive.
850 static void make_gray_object(unsigned long ptr)
852 paint_ptr(ptr, KMEMLEAK_GREY, false);
856 * Mark the object as black-colored so that it is ignored from scans and
859 static void make_black_object(unsigned long ptr, bool is_phys)
861 paint_ptr(ptr, KMEMLEAK_BLACK, is_phys);
865 * Add a scanning area to the object. If at least one such area is added,
866 * kmemleak will only scan these ranges rather than the whole memory block.
868 static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
871 struct kmemleak_object *object;
872 struct kmemleak_scan_area *area = NULL;
873 unsigned long untagged_ptr;
874 unsigned long untagged_objp;
876 object = find_and_get_object(ptr, 1);
878 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
883 untagged_ptr = (unsigned long)kasan_reset_tag((void *)ptr);
884 untagged_objp = (unsigned long)kasan_reset_tag((void *)object->pointer);
887 area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
889 raw_spin_lock_irqsave(&object->lock, flags);
891 pr_warn_once("Cannot allocate a scan area, scanning the full object\n");
892 /* mark the object for full scan to avoid false positives */
893 object->flags |= OBJECT_FULL_SCAN;
896 if (size == SIZE_MAX) {
897 size = untagged_objp + object->size - untagged_ptr;
898 } else if (untagged_ptr + size > untagged_objp + object->size) {
899 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
900 dump_object_info(object);
901 kmem_cache_free(scan_area_cache, area);
905 INIT_HLIST_NODE(&area->node);
909 hlist_add_head(&area->node, &object->area_list);
911 raw_spin_unlock_irqrestore(&object->lock, flags);
916 * Any surplus references (object already gray) to 'ptr' are passed to
917 * 'excess_ref'. This is used in the vmalloc() case where a pointer to
918 * vm_struct may be used as an alternative reference to the vmalloc'ed object
919 * (see free_thread_stack()).
921 static void object_set_excess_ref(unsigned long ptr, unsigned long excess_ref)
924 struct kmemleak_object *object;
926 object = find_and_get_object(ptr, 0);
928 kmemleak_warn("Setting excess_ref on unknown object at 0x%08lx\n",
933 raw_spin_lock_irqsave(&object->lock, flags);
934 object->excess_ref = excess_ref;
935 raw_spin_unlock_irqrestore(&object->lock, flags);
940 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
941 * pointer. Such object will not be scanned by kmemleak but references to it
944 static void object_no_scan(unsigned long ptr)
947 struct kmemleak_object *object;
949 object = find_and_get_object(ptr, 0);
951 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
955 raw_spin_lock_irqsave(&object->lock, flags);
956 object->flags |= OBJECT_NO_SCAN;
957 raw_spin_unlock_irqrestore(&object->lock, flags);
962 * kmemleak_alloc - register a newly allocated object
963 * @ptr: pointer to beginning of the object
964 * @size: size of the object
965 * @min_count: minimum number of references to this object. If during memory
966 * scanning a number of references less than @min_count is found,
967 * the object is reported as a memory leak. If @min_count is 0,
968 * the object is never reported as a leak. If @min_count is -1,
969 * the object is ignored (not scanned and not reported as a leak)
970 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
972 * This function is called from the kernel allocators when a new object
973 * (memory block) is allocated (kmem_cache_alloc, kmalloc etc.).
975 void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
978 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
980 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
981 create_object((unsigned long)ptr, size, min_count, gfp);
983 EXPORT_SYMBOL_GPL(kmemleak_alloc);
986 * kmemleak_alloc_percpu - register a newly allocated __percpu object
987 * @ptr: __percpu pointer to beginning of the object
988 * @size: size of the object
989 * @gfp: flags used for kmemleak internal memory allocations
991 * This function is called from the kernel percpu allocator when a new object
992 * (memory block) is allocated (alloc_percpu).
994 void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size,
999 pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
1002 * Percpu allocations are only scanned and not reported as leaks
1003 * (min_count is set to 0).
1005 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1006 for_each_possible_cpu(cpu)
1007 create_object((unsigned long)per_cpu_ptr(ptr, cpu),
1010 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
1013 * kmemleak_vmalloc - register a newly vmalloc'ed object
1014 * @area: pointer to vm_struct
1015 * @size: size of the object
1016 * @gfp: __vmalloc() flags used for kmemleak internal memory allocations
1018 * This function is called from the vmalloc() kernel allocator when a new
1019 * object (memory block) is allocated.
1021 void __ref kmemleak_vmalloc(const struct vm_struct *area, size_t size, gfp_t gfp)
1023 pr_debug("%s(0x%p, %zu)\n", __func__, area, size);
1026 * A min_count = 2 is needed because vm_struct contains a reference to
1027 * the virtual address of the vmalloc'ed block.
1029 if (kmemleak_enabled) {
1030 create_object((unsigned long)area->addr, size, 2, gfp);
1031 object_set_excess_ref((unsigned long)area,
1032 (unsigned long)area->addr);
1035 EXPORT_SYMBOL_GPL(kmemleak_vmalloc);
1038 * kmemleak_free - unregister a previously registered object
1039 * @ptr: pointer to beginning of the object
1041 * This function is called from the kernel allocators when an object (memory
1042 * block) is freed (kmem_cache_free, kfree, vfree etc.).
1044 void __ref kmemleak_free(const void *ptr)
1046 pr_debug("%s(0x%p)\n", __func__, ptr);
1048 if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
1049 delete_object_full((unsigned long)ptr);
1051 EXPORT_SYMBOL_GPL(kmemleak_free);
1054 * kmemleak_free_part - partially unregister a previously registered object
1055 * @ptr: pointer to the beginning or inside the object. This also
1056 * represents the start of the range to be freed
1057 * @size: size to be unregistered
1059 * This function is called when only a part of a memory block is freed
1060 * (usually from the bootmem allocator).
1062 void __ref kmemleak_free_part(const void *ptr, size_t size)
1064 pr_debug("%s(0x%p)\n", __func__, ptr);
1066 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1067 delete_object_part((unsigned long)ptr, size, false);
1069 EXPORT_SYMBOL_GPL(kmemleak_free_part);
1072 * kmemleak_free_percpu - unregister a previously registered __percpu object
1073 * @ptr: __percpu pointer to beginning of the object
1075 * This function is called from the kernel percpu allocator when an object
1076 * (memory block) is freed (free_percpu).
1078 void __ref kmemleak_free_percpu(const void __percpu *ptr)
1082 pr_debug("%s(0x%p)\n", __func__, ptr);
1084 if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
1085 for_each_possible_cpu(cpu)
1086 delete_object_full((unsigned long)per_cpu_ptr(ptr,
1089 EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
1092 * kmemleak_update_trace - update object allocation stack trace
1093 * @ptr: pointer to beginning of the object
1095 * Override the object allocation stack trace for cases where the actual
1096 * allocation place is not always useful.
1098 void __ref kmemleak_update_trace(const void *ptr)
1100 struct kmemleak_object *object;
1101 unsigned long flags;
1103 pr_debug("%s(0x%p)\n", __func__, ptr);
1105 if (!kmemleak_enabled || IS_ERR_OR_NULL(ptr))
1108 object = find_and_get_object((unsigned long)ptr, 1);
1111 kmemleak_warn("Updating stack trace for unknown object at %p\n",
1117 raw_spin_lock_irqsave(&object->lock, flags);
1118 object->trace_handle = set_track_prepare();
1119 raw_spin_unlock_irqrestore(&object->lock, flags);
1123 EXPORT_SYMBOL(kmemleak_update_trace);
1126 * kmemleak_not_leak - mark an allocated object as false positive
1127 * @ptr: pointer to beginning of the object
1129 * Calling this function on an object will cause the memory block to no longer
1130 * be reported as leak and always be scanned.
1132 void __ref kmemleak_not_leak(const void *ptr)
1134 pr_debug("%s(0x%p)\n", __func__, ptr);
1136 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1137 make_gray_object((unsigned long)ptr);
1139 EXPORT_SYMBOL(kmemleak_not_leak);
1142 * kmemleak_ignore - ignore an allocated object
1143 * @ptr: pointer to beginning of the object
1145 * Calling this function on an object will cause the memory block to be
1146 * ignored (not scanned and not reported as a leak). This is usually done when
1147 * it is known that the corresponding block is not a leak and does not contain
1148 * any references to other allocated memory blocks.
1150 void __ref kmemleak_ignore(const void *ptr)
1152 pr_debug("%s(0x%p)\n", __func__, ptr);
1154 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1155 make_black_object((unsigned long)ptr, false);
1157 EXPORT_SYMBOL(kmemleak_ignore);
1160 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1161 * @ptr: pointer to beginning or inside the object. This also
1162 * represents the start of the scan area
1163 * @size: size of the scan area
1164 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1166 * This function is used when it is known that only certain parts of an object
1167 * contain references to other objects. Kmemleak will only scan these areas
1168 * reducing the number false negatives.
1170 void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
1172 pr_debug("%s(0x%p)\n", __func__, ptr);
1174 if (kmemleak_enabled && ptr && size && !IS_ERR(ptr))
1175 add_scan_area((unsigned long)ptr, size, gfp);
1177 EXPORT_SYMBOL(kmemleak_scan_area);
1180 * kmemleak_no_scan - do not scan an allocated object
1181 * @ptr: pointer to beginning of the object
1183 * This function notifies kmemleak not to scan the given memory block. Useful
1184 * in situations where it is known that the given object does not contain any
1185 * references to other objects. Kmemleak will not scan such objects reducing
1186 * the number of false negatives.
1188 void __ref kmemleak_no_scan(const void *ptr)
1190 pr_debug("%s(0x%p)\n", __func__, ptr);
1192 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1193 object_no_scan((unsigned long)ptr);
1195 EXPORT_SYMBOL(kmemleak_no_scan);
1198 * kmemleak_alloc_phys - similar to kmemleak_alloc but taking a physical
1200 * @phys: physical address of the object
1201 * @size: size of the object
1202 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1204 void __ref kmemleak_alloc_phys(phys_addr_t phys, size_t size, gfp_t gfp)
1206 pr_debug("%s(0x%pa, %zu)\n", __func__, &phys, size);
1208 if (kmemleak_enabled)
1210 * Create object with OBJECT_PHYS flag and
1211 * assume min_count 0.
1213 create_object_phys((unsigned long)phys, size, 0, gfp);
1215 EXPORT_SYMBOL(kmemleak_alloc_phys);
1218 * kmemleak_free_part_phys - similar to kmemleak_free_part but taking a
1219 * physical address argument
1220 * @phys: physical address if the beginning or inside an object. This
1221 * also represents the start of the range to be freed
1222 * @size: size to be unregistered
1224 void __ref kmemleak_free_part_phys(phys_addr_t phys, size_t size)
1226 pr_debug("%s(0x%pa)\n", __func__, &phys);
1228 if (kmemleak_enabled)
1229 delete_object_part((unsigned long)phys, size, true);
1231 EXPORT_SYMBOL(kmemleak_free_part_phys);
1234 * kmemleak_ignore_phys - similar to kmemleak_ignore but taking a physical
1236 * @phys: physical address of the object
1238 void __ref kmemleak_ignore_phys(phys_addr_t phys)
1240 pr_debug("%s(0x%pa)\n", __func__, &phys);
1242 if (kmemleak_enabled)
1243 make_black_object((unsigned long)phys, true);
1245 EXPORT_SYMBOL(kmemleak_ignore_phys);
1248 * Update an object's checksum and return true if it was modified.
1250 static bool update_checksum(struct kmemleak_object *object)
1252 u32 old_csum = object->checksum;
1254 if (WARN_ON_ONCE(object->flags & OBJECT_PHYS))
1257 kasan_disable_current();
1258 kcsan_disable_current();
1259 object->checksum = crc32(0, kasan_reset_tag((void *)object->pointer), object->size);
1260 kasan_enable_current();
1261 kcsan_enable_current();
1263 return object->checksum != old_csum;
1267 * Update an object's references. object->lock must be held by the caller.
1269 static void update_refs(struct kmemleak_object *object)
1271 if (!color_white(object)) {
1272 /* non-orphan, ignored or new */
1277 * Increase the object's reference count (number of pointers to the
1278 * memory block). If this count reaches the required minimum, the
1279 * object's color will become gray and it will be added to the
1283 if (color_gray(object)) {
1284 /* put_object() called when removing from gray_list */
1285 WARN_ON(!get_object(object));
1286 list_add_tail(&object->gray_list, &gray_list);
1291 * Memory scanning is a long process and it needs to be interruptible. This
1292 * function checks whether such interrupt condition occurred.
1294 static int scan_should_stop(void)
1296 if (!kmemleak_enabled)
1300 * This function may be called from either process or kthread context,
1301 * hence the need to check for both stop conditions.
1304 return signal_pending(current);
1306 return kthread_should_stop();
1312 * Scan a memory block (exclusive range) for valid pointers and add those
1313 * found to the gray list.
1315 static void scan_block(void *_start, void *_end,
1316 struct kmemleak_object *scanned)
1319 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1320 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1321 unsigned long flags;
1322 unsigned long untagged_ptr;
1324 raw_spin_lock_irqsave(&kmemleak_lock, flags);
1325 for (ptr = start; ptr < end; ptr++) {
1326 struct kmemleak_object *object;
1327 unsigned long pointer;
1328 unsigned long excess_ref;
1330 if (scan_should_stop())
1333 kasan_disable_current();
1334 pointer = *(unsigned long *)kasan_reset_tag((void *)ptr);
1335 kasan_enable_current();
1337 untagged_ptr = (unsigned long)kasan_reset_tag((void *)pointer);
1338 if (untagged_ptr < min_addr || untagged_ptr >= max_addr)
1342 * No need for get_object() here since we hold kmemleak_lock.
1343 * object->use_count cannot be dropped to 0 while the object
1344 * is still present in object_tree_root and object_list
1345 * (with updates protected by kmemleak_lock).
1347 object = lookup_object(pointer, 1);
1350 if (object == scanned)
1351 /* self referenced, ignore */
1355 * Avoid the lockdep recursive warning on object->lock being
1356 * previously acquired in scan_object(). These locks are
1357 * enclosed by scan_mutex.
1359 raw_spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
1360 /* only pass surplus references (object already gray) */
1361 if (color_gray(object)) {
1362 excess_ref = object->excess_ref;
1363 /* no need for update_refs() if object already gray */
1366 update_refs(object);
1368 raw_spin_unlock(&object->lock);
1371 object = lookup_object(excess_ref, 0);
1374 if (object == scanned)
1375 /* circular reference, ignore */
1377 raw_spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
1378 update_refs(object);
1379 raw_spin_unlock(&object->lock);
1382 raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
1386 * Scan a large memory block in MAX_SCAN_SIZE chunks to reduce the latency.
1389 static void scan_large_block(void *start, void *end)
1393 while (start < end) {
1394 next = min(start + MAX_SCAN_SIZE, end);
1395 scan_block(start, next, NULL);
1403 * Scan a memory block corresponding to a kmemleak_object. A condition is
1404 * that object->use_count >= 1.
1406 static void scan_object(struct kmemleak_object *object)
1408 struct kmemleak_scan_area *area;
1409 unsigned long flags;
1413 * Once the object->lock is acquired, the corresponding memory block
1414 * cannot be freed (the same lock is acquired in delete_object).
1416 raw_spin_lock_irqsave(&object->lock, flags);
1417 if (object->flags & OBJECT_NO_SCAN)
1419 if (!(object->flags & OBJECT_ALLOCATED))
1420 /* already freed object */
1423 obj_ptr = object->flags & OBJECT_PHYS ?
1424 __va((phys_addr_t)object->pointer) :
1425 (void *)object->pointer;
1427 if (hlist_empty(&object->area_list) ||
1428 object->flags & OBJECT_FULL_SCAN) {
1429 void *start = obj_ptr;
1430 void *end = obj_ptr + object->size;
1434 next = min(start + MAX_SCAN_SIZE, end);
1435 scan_block(start, next, object);
1441 raw_spin_unlock_irqrestore(&object->lock, flags);
1443 raw_spin_lock_irqsave(&object->lock, flags);
1444 } while (object->flags & OBJECT_ALLOCATED);
1446 hlist_for_each_entry(area, &object->area_list, node)
1447 scan_block((void *)area->start,
1448 (void *)(area->start + area->size),
1451 raw_spin_unlock_irqrestore(&object->lock, flags);
1455 * Scan the objects already referenced (gray objects). More objects will be
1456 * referenced and, if there are no memory leaks, all the objects are scanned.
1458 static void scan_gray_list(void)
1460 struct kmemleak_object *object, *tmp;
1463 * The list traversal is safe for both tail additions and removals
1464 * from inside the loop. The kmemleak objects cannot be freed from
1465 * outside the loop because their use_count was incremented.
1467 object = list_entry(gray_list.next, typeof(*object), gray_list);
1468 while (&object->gray_list != &gray_list) {
1471 /* may add new objects to the list */
1472 if (!scan_should_stop())
1473 scan_object(object);
1475 tmp = list_entry(object->gray_list.next, typeof(*object),
1478 /* remove the object from the list and release it */
1479 list_del(&object->gray_list);
1484 WARN_ON(!list_empty(&gray_list));
1488 * Conditionally call resched() in an object iteration loop while making sure
1489 * that the given object won't go away without RCU read lock by performing a
1490 * get_object() if necessaary.
1492 static void kmemleak_cond_resched(struct kmemleak_object *object)
1494 if (!get_object(object))
1495 return; /* Try next object */
1497 raw_spin_lock_irq(&kmemleak_lock);
1498 if (object->del_state & DELSTATE_REMOVED)
1499 goto unlock_put; /* Object removed */
1500 object->del_state |= DELSTATE_NO_DELETE;
1501 raw_spin_unlock_irq(&kmemleak_lock);
1507 raw_spin_lock_irq(&kmemleak_lock);
1508 if (object->del_state & DELSTATE_REMOVED)
1509 list_del_rcu(&object->object_list);
1510 object->del_state &= ~DELSTATE_NO_DELETE;
1512 raw_spin_unlock_irq(&kmemleak_lock);
1517 * Scan data sections and all the referenced memory blocks allocated via the
1518 * kernel's standard allocators. This function must be called with the
1521 static void kmemleak_scan(void)
1523 struct kmemleak_object *object;
1525 int __maybe_unused i;
1528 jiffies_last_scan = jiffies;
1530 /* prepare the kmemleak_object's */
1532 list_for_each_entry_rcu(object, &object_list, object_list) {
1533 raw_spin_lock_irq(&object->lock);
1536 * With a few exceptions there should be a maximum of
1537 * 1 reference to any object at this point.
1539 if (atomic_read(&object->use_count) > 1) {
1540 pr_debug("object->use_count = %d\n",
1541 atomic_read(&object->use_count));
1542 dump_object_info(object);
1546 /* ignore objects outside lowmem (paint them black) */
1547 if ((object->flags & OBJECT_PHYS) &&
1548 !(object->flags & OBJECT_NO_SCAN)) {
1549 unsigned long phys = object->pointer;
1551 if (PHYS_PFN(phys) < min_low_pfn ||
1552 PHYS_PFN(phys + object->size) >= max_low_pfn)
1553 __paint_it(object, KMEMLEAK_BLACK);
1556 /* reset the reference count (whiten the object) */
1558 if (color_gray(object) && get_object(object))
1559 list_add_tail(&object->gray_list, &gray_list);
1561 raw_spin_unlock_irq(&object->lock);
1564 kmemleak_cond_resched(object);
1569 /* per-cpu sections scanning */
1570 for_each_possible_cpu(i)
1571 scan_large_block(__per_cpu_start + per_cpu_offset(i),
1572 __per_cpu_end + per_cpu_offset(i));
1576 * Struct page scanning for each node.
1579 for_each_populated_zone(zone) {
1580 unsigned long start_pfn = zone->zone_start_pfn;
1581 unsigned long end_pfn = zone_end_pfn(zone);
1584 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1585 struct page *page = pfn_to_online_page(pfn);
1590 /* only scan pages belonging to this zone */
1591 if (page_zone(page) != zone)
1593 /* only scan if page is in use */
1594 if (page_count(page) == 0)
1596 scan_block(page, page + 1, NULL);
1604 * Scanning the task stacks (may introduce false negatives).
1606 if (kmemleak_stack_scan) {
1607 struct task_struct *p, *g;
1610 for_each_process_thread(g, p) {
1611 void *stack = try_get_task_stack(p);
1613 scan_block(stack, stack + THREAD_SIZE, NULL);
1621 * Scan the objects already referenced from the sections scanned
1627 * Check for new or unreferenced objects modified since the previous
1628 * scan and color them gray until the next scan.
1631 list_for_each_entry_rcu(object, &object_list, object_list) {
1633 kmemleak_cond_resched(object);
1636 * This is racy but we can save the overhead of lock/unlock
1637 * calls. The missed objects, if any, should be caught in
1640 if (!color_white(object))
1642 raw_spin_lock_irq(&object->lock);
1643 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1644 && update_checksum(object) && get_object(object)) {
1645 /* color it gray temporarily */
1646 object->count = object->min_count;
1647 list_add_tail(&object->gray_list, &gray_list);
1649 raw_spin_unlock_irq(&object->lock);
1654 * Re-scan the gray list for modified unreferenced objects.
1659 * If scanning was stopped do not report any new unreferenced objects.
1661 if (scan_should_stop())
1665 * Scanning result reporting.
1668 list_for_each_entry_rcu(object, &object_list, object_list) {
1670 kmemleak_cond_resched(object);
1673 * This is racy but we can save the overhead of lock/unlock
1674 * calls. The missed objects, if any, should be caught in
1677 if (!color_white(object))
1679 raw_spin_lock_irq(&object->lock);
1680 if (unreferenced_object(object) &&
1681 !(object->flags & OBJECT_REPORTED)) {
1682 object->flags |= OBJECT_REPORTED;
1684 if (kmemleak_verbose)
1685 print_unreferenced(NULL, object);
1689 raw_spin_unlock_irq(&object->lock);
1694 kmemleak_found_leaks = true;
1696 pr_info("%d new suspected memory leaks (see /sys/kernel/debug/kmemleak)\n",
1703 * Thread function performing automatic memory scanning. Unreferenced objects
1704 * at the end of a memory scan are reported but only the first time.
1706 static int kmemleak_scan_thread(void *arg)
1708 static int first_run = IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN);
1710 pr_info("Automatic memory scanning thread started\n");
1711 set_user_nice(current, 10);
1714 * Wait before the first scan to allow the system to fully initialize.
1717 signed long timeout = msecs_to_jiffies(SECS_FIRST_SCAN * 1000);
1719 while (timeout && !kthread_should_stop())
1720 timeout = schedule_timeout_interruptible(timeout);
1723 while (!kthread_should_stop()) {
1724 signed long timeout = READ_ONCE(jiffies_scan_wait);
1726 mutex_lock(&scan_mutex);
1728 mutex_unlock(&scan_mutex);
1730 /* wait before the next scan */
1731 while (timeout && !kthread_should_stop())
1732 timeout = schedule_timeout_interruptible(timeout);
1735 pr_info("Automatic memory scanning thread ended\n");
1741 * Start the automatic memory scanning thread. This function must be called
1742 * with the scan_mutex held.
1744 static void start_scan_thread(void)
1748 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1749 if (IS_ERR(scan_thread)) {
1750 pr_warn("Failed to create the scan thread\n");
1756 * Stop the automatic memory scanning thread.
1758 static void stop_scan_thread(void)
1761 kthread_stop(scan_thread);
1767 * Iterate over the object_list and return the first valid object at or after
1768 * the required position with its use_count incremented. The function triggers
1769 * a memory scanning when the pos argument points to the first position.
1771 static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1773 struct kmemleak_object *object;
1777 err = mutex_lock_interruptible(&scan_mutex);
1779 return ERR_PTR(err);
1782 list_for_each_entry_rcu(object, &object_list, object_list) {
1785 if (get_object(object))
1794 * Return the next object in the object_list. The function decrements the
1795 * use_count of the previous object and increases that of the next one.
1797 static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1799 struct kmemleak_object *prev_obj = v;
1800 struct kmemleak_object *next_obj = NULL;
1801 struct kmemleak_object *obj = prev_obj;
1805 list_for_each_entry_continue_rcu(obj, &object_list, object_list) {
1806 if (get_object(obj)) {
1812 put_object(prev_obj);
1817 * Decrement the use_count of the last object required, if any.
1819 static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1823 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1824 * waiting was interrupted, so only release it if !IS_ERR.
1827 mutex_unlock(&scan_mutex);
1834 * Print the information for an unreferenced object to the seq file.
1836 static int kmemleak_seq_show(struct seq_file *seq, void *v)
1838 struct kmemleak_object *object = v;
1839 unsigned long flags;
1841 raw_spin_lock_irqsave(&object->lock, flags);
1842 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
1843 print_unreferenced(seq, object);
1844 raw_spin_unlock_irqrestore(&object->lock, flags);
1848 static const struct seq_operations kmemleak_seq_ops = {
1849 .start = kmemleak_seq_start,
1850 .next = kmemleak_seq_next,
1851 .stop = kmemleak_seq_stop,
1852 .show = kmemleak_seq_show,
1855 static int kmemleak_open(struct inode *inode, struct file *file)
1857 return seq_open(file, &kmemleak_seq_ops);
1860 static int dump_str_object_info(const char *str)
1862 unsigned long flags;
1863 struct kmemleak_object *object;
1866 if (kstrtoul(str, 0, &addr))
1868 object = find_and_get_object(addr, 0);
1870 pr_info("Unknown object at 0x%08lx\n", addr);
1874 raw_spin_lock_irqsave(&object->lock, flags);
1875 dump_object_info(object);
1876 raw_spin_unlock_irqrestore(&object->lock, flags);
1883 * We use grey instead of black to ensure we can do future scans on the same
1884 * objects. If we did not do future scans these black objects could
1885 * potentially contain references to newly allocated objects in the future and
1886 * we'd end up with false positives.
1888 static void kmemleak_clear(void)
1890 struct kmemleak_object *object;
1893 list_for_each_entry_rcu(object, &object_list, object_list) {
1894 raw_spin_lock_irq(&object->lock);
1895 if ((object->flags & OBJECT_REPORTED) &&
1896 unreferenced_object(object))
1897 __paint_it(object, KMEMLEAK_GREY);
1898 raw_spin_unlock_irq(&object->lock);
1902 kmemleak_found_leaks = false;
1905 static void __kmemleak_do_cleanup(void);
1908 * File write operation to configure kmemleak at run-time. The following
1909 * commands can be written to the /sys/kernel/debug/kmemleak file:
1910 * off - disable kmemleak (irreversible)
1911 * stack=on - enable the task stacks scanning
1912 * stack=off - disable the tasks stacks scanning
1913 * scan=on - start the automatic memory scanning thread
1914 * scan=off - stop the automatic memory scanning thread
1915 * scan=... - set the automatic memory scanning period in seconds (0 to
1917 * scan - trigger a memory scan
1918 * clear - mark all current reported unreferenced kmemleak objects as
1919 * grey to ignore printing them, or free all kmemleak objects
1920 * if kmemleak has been disabled.
1921 * dump=... - dump information about the object found at the given address
1923 static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1924 size_t size, loff_t *ppos)
1930 buf_size = min(size, (sizeof(buf) - 1));
1931 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1935 ret = mutex_lock_interruptible(&scan_mutex);
1939 if (strncmp(buf, "clear", 5) == 0) {
1940 if (kmemleak_enabled)
1943 __kmemleak_do_cleanup();
1947 if (!kmemleak_enabled) {
1952 if (strncmp(buf, "off", 3) == 0)
1954 else if (strncmp(buf, "stack=on", 8) == 0)
1955 kmemleak_stack_scan = 1;
1956 else if (strncmp(buf, "stack=off", 9) == 0)
1957 kmemleak_stack_scan = 0;
1958 else if (strncmp(buf, "scan=on", 7) == 0)
1959 start_scan_thread();
1960 else if (strncmp(buf, "scan=off", 8) == 0)
1962 else if (strncmp(buf, "scan=", 5) == 0) {
1964 unsigned long msecs;
1966 ret = kstrtouint(buf + 5, 0, &secs);
1970 msecs = secs * MSEC_PER_SEC;
1971 if (msecs > UINT_MAX)
1976 WRITE_ONCE(jiffies_scan_wait, msecs_to_jiffies(msecs));
1977 start_scan_thread();
1979 } else if (strncmp(buf, "scan", 4) == 0)
1981 else if (strncmp(buf, "dump=", 5) == 0)
1982 ret = dump_str_object_info(buf + 5);
1987 mutex_unlock(&scan_mutex);
1991 /* ignore the rest of the buffer, only one command at a time */
1996 static const struct file_operations kmemleak_fops = {
1997 .owner = THIS_MODULE,
1998 .open = kmemleak_open,
2000 .write = kmemleak_write,
2001 .llseek = seq_lseek,
2002 .release = seq_release,
2005 static void __kmemleak_do_cleanup(void)
2007 struct kmemleak_object *object, *tmp;
2010 * Kmemleak has already been disabled, no need for RCU list traversal
2011 * or kmemleak_lock held.
2013 list_for_each_entry_safe(object, tmp, &object_list, object_list) {
2014 __remove_object(object);
2015 __delete_object(object);
2020 * Stop the memory scanning thread and free the kmemleak internal objects if
2021 * no previous scan thread (otherwise, kmemleak may still have some useful
2022 * information on memory leaks).
2024 static void kmemleak_do_cleanup(struct work_struct *work)
2028 mutex_lock(&scan_mutex);
2030 * Once it is made sure that kmemleak_scan has stopped, it is safe to no
2031 * longer track object freeing. Ordering of the scan thread stopping and
2032 * the memory accesses below is guaranteed by the kthread_stop()
2035 kmemleak_free_enabled = 0;
2036 mutex_unlock(&scan_mutex);
2038 if (!kmemleak_found_leaks)
2039 __kmemleak_do_cleanup();
2041 pr_info("Kmemleak disabled without freeing internal data. Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\".\n");
2044 static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
2047 * Disable kmemleak. No memory allocation/freeing will be traced once this
2048 * function is called. Disabling kmemleak is an irreversible operation.
2050 static void kmemleak_disable(void)
2052 /* atomically check whether it was already invoked */
2053 if (cmpxchg(&kmemleak_error, 0, 1))
2056 /* stop any memory operation tracing */
2057 kmemleak_enabled = 0;
2059 /* check whether it is too early for a kernel thread */
2060 if (kmemleak_late_initialized)
2061 schedule_work(&cleanup_work);
2063 kmemleak_free_enabled = 0;
2065 pr_info("Kernel memory leak detector disabled\n");
2069 * Allow boot-time kmemleak disabling (enabled by default).
2071 static int __init kmemleak_boot_config(char *str)
2075 if (strcmp(str, "off") == 0)
2077 else if (strcmp(str, "on") == 0) {
2078 kmemleak_skip_disable = 1;
2079 stack_depot_request_early_init();
2085 early_param("kmemleak", kmemleak_boot_config);
2088 * Kmemleak initialization.
2090 void __init kmemleak_init(void)
2092 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
2093 if (!kmemleak_skip_disable) {
2102 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
2103 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
2105 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
2106 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
2108 /* register the data/bss sections */
2109 create_object((unsigned long)_sdata, _edata - _sdata,
2110 KMEMLEAK_GREY, GFP_ATOMIC);
2111 create_object((unsigned long)__bss_start, __bss_stop - __bss_start,
2112 KMEMLEAK_GREY, GFP_ATOMIC);
2113 /* only register .data..ro_after_init if not within .data */
2114 if (&__start_ro_after_init < &_sdata || &__end_ro_after_init > &_edata)
2115 create_object((unsigned long)__start_ro_after_init,
2116 __end_ro_after_init - __start_ro_after_init,
2117 KMEMLEAK_GREY, GFP_ATOMIC);
2121 * Late initialization function.
2123 static int __init kmemleak_late_init(void)
2125 kmemleak_late_initialized = 1;
2127 debugfs_create_file("kmemleak", 0644, NULL, NULL, &kmemleak_fops);
2129 if (kmemleak_error) {
2131 * Some error occurred and kmemleak was disabled. There is a
2132 * small chance that kmemleak_disable() was called immediately
2133 * after setting kmemleak_late_initialized and we may end up with
2134 * two clean-up threads but serialized by scan_mutex.
2136 schedule_work(&cleanup_work);
2140 if (IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN)) {
2141 mutex_lock(&scan_mutex);
2142 start_scan_thread();
2143 mutex_unlock(&scan_mutex);
2146 pr_info("Kernel memory leak detector initialized (mem pool available: %d)\n",
2147 mem_pool_free_count);
2151 late_initcall(kmemleak_late_init);