root/mm/kmemleak.c

DEFINITIONS

1. warn_or_seq_hex_dump
2. hex_dump_object
3. color_white
4. color_gray
5. unreferenced_object
6. print_unreferenced
7. dump_object_info
8. lookup_object
9. get_object
10. mem_pool_alloc
11. mem_pool_free
12. free_object_rcu
13. put_object
14. find_and_get_object
15. __remove_object
16. find_and_remove_object
17. __save_stack_trace
18. create_object
19. __delete_object
20. delete_object_full
21. delete_object_part
22. __paint_it
23. paint_it
24. paint_ptr
25. make_gray_object
26. make_black_object
27. add_scan_area
28. object_set_excess_ref
29. object_no_scan
30. kmemleak_alloc
31. kmemleak_alloc_percpu
32. kmemleak_vmalloc
33. kmemleak_free
34. kmemleak_free_part
35. kmemleak_free_percpu
36. kmemleak_update_trace
37. kmemleak_not_leak
38. kmemleak_ignore
39. kmemleak_scan_area
40. kmemleak_no_scan
41. kmemleak_alloc_phys
42. kmemleak_free_part_phys
43. kmemleak_not_leak_phys
44. kmemleak_ignore_phys
45. update_checksum
46. update_refs
47. scan_should_stop
48. scan_block
49. scan_large_block
50. scan_object
51. scan_gray_list
52. kmemleak_scan
53. kmemleak_scan_thread
54. start_scan_thread
55. stop_scan_thread
56. kmemleak_seq_start
57. kmemleak_seq_next
58. kmemleak_seq_stop
59. kmemleak_seq_show
60. kmemleak_open
61. dump_str_object_info
62. kmemleak_clear
63. kmemleak_write
64. __kmemleak_do_cleanup
65. kmemleak_do_cleanup
66. kmemleak_disable
67. kmemleak_boot_config
68. kmemleak_init
69. kmemleak_late_init

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * mm/kmemleak.c
   4  *
   5  * Copyright (C) 2008 ARM Limited
   6  * Written by Catalin Marinas <catalin.marinas@arm.com>
   7  *
   8  * For more information on the algorithm and kmemleak usage, please see
   9  * Documentation/dev-tools/kmemleak.rst.
  10  *
  11  * Notes on locking
  12  * ----------------
  13  *
  14  * The following locks and mutexes are used by kmemleak:
  15  *
  16  * - kmemleak_lock (rwlock): protects the object_list modifications and
  17  *   accesses to the object_tree_root. The object_list is the main list
  18  *   holding the metadata (struct kmemleak_object) for the allocated memory
  19  *   blocks. The object_tree_root is a red black tree used to look-up
  20  *   metadata based on a pointer to the corresponding memory block.  The
  21  *   kmemleak_object structures are added to the object_list and
  22  *   object_tree_root in the create_object() function called from the
  23  *   kmemleak_alloc() callback and removed in delete_object() called from the
  24  *   kmemleak_free() callback
  25  * - kmemleak_object.lock (spinlock): protects a kmemleak_object. Accesses to
  26  *   the metadata (e.g. count) are protected by this lock. Note that some
  27  *   members of this structure may be protected by other means (atomic or
  28  *   kmemleak_lock). This lock is also held when scanning the corresponding
  29  *   memory block to avoid the kernel freeing it via the kmemleak_free()
  30  *   callback. This is less heavyweight than holding a global lock like
  31  *   kmemleak_lock during scanning
  32  * - scan_mutex (mutex): ensures that only one thread may scan the memory for
  33  *   unreferenced objects at a time. The gray_list contains the objects which
  34  *   are already referenced or marked as false positives and need to be
  35  *   scanned. This list is only modified during a scanning episode when the
  36  *   scan_mutex is held. At the end of a scan, the gray_list is always empty.
  37  *   Note that the kmemleak_object.use_count is incremented when an object is
  38  *   added to the gray_list and therefore cannot be freed. This mutex also
  39  *   prevents multiple users of the "kmemleak" debugfs file together with
  40  *   modifications to the memory scanning parameters including the scan_thread
  41  *   pointer
  42  *
  43  * Locks and mutexes are acquired/nested in the following order:
  44  *
  45  *   scan_mutex [-> object->lock] -> kmemleak_lock -> other_object->lock (SINGLE_DEPTH_NESTING)
  46  *
  47  * No kmemleak_lock and object->lock nesting is allowed outside scan_mutex
  48  * regions.
  49  *
  50  * The kmemleak_object structures have a use_count incremented or decremented
  51  * using the get_object()/put_object() functions. When the use_count becomes
  52  * 0, this count can no longer be incremented and put_object() schedules the
  53  * kmemleak_object freeing via an RCU callback. All calls to the get_object()
  54  * function must be protected by rcu_read_lock() to avoid accessing a freed
  55  * structure.
  56  */
  57 
  58 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  59 
  60 #include <linux/init.h>
  61 #include <linux/kernel.h>
  62 #include <linux/list.h>
  63 #include <linux/sched/signal.h>
  64 #include <linux/sched/task.h>
  65 #include <linux/sched/task_stack.h>
  66 #include <linux/jiffies.h>
  67 #include <linux/delay.h>
  68 #include <linux/export.h>
  69 #include <linux/kthread.h>
  70 #include <linux/rbtree.h>
  71 #include <linux/fs.h>
  72 #include <linux/debugfs.h>
  73 #include <linux/seq_file.h>
  74 #include <linux/cpumask.h>
  75 #include <linux/spinlock.h>
  76 #include <linux/module.h>
  77 #include <linux/mutex.h>
  78 #include <linux/rcupdate.h>
  79 #include <linux/stacktrace.h>
  80 #include <linux/cache.h>
  81 #include <linux/percpu.h>
  82 #include <linux/memblock.h>
  83 #include <linux/pfn.h>
  84 #include <linux/mmzone.h>
  85 #include <linux/slab.h>
  86 #include <linux/thread_info.h>
  87 #include <linux/err.h>
  88 #include <linux/uaccess.h>
  89 #include <linux/string.h>
  90 #include <linux/nodemask.h>
  91 #include <linux/mm.h>
  92 #include <linux/workqueue.h>
  93 #include <linux/crc32.h>
  94 
  95 #include <asm/sections.h>
  96 #include <asm/processor.h>
  97 #include <linux/atomic.h>
  98 
  99 #include <linux/kasan.h>
 100 #include <linux/kmemleak.h>
 101 #include <linux/memory_hotplug.h>
 102 
 103 /*
 104  * Kmemleak configuration and common defines.
 105  */
 106 #define MAX_TRACE               16      /* stack trace length */
 107 #define MSECS_MIN_AGE           5000    /* minimum object age for reporting */
 108 #define SECS_FIRST_SCAN         60      /* delay before the first scan */
 109 #define SECS_SCAN_WAIT          600     /* subsequent auto scanning delay */
 110 #define MAX_SCAN_SIZE           4096    /* maximum size of a scanned block */
 111 
 112 #define BYTES_PER_POINTER       sizeof(void *)
 113 
 114 /* GFP bitmask for kmemleak internal allocations */
 115 #define gfp_kmemleak_mask(gfp)  (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
 116                                  __GFP_NORETRY | __GFP_NOMEMALLOC | \
 117                                  __GFP_NOWARN)
 118 
 119 /* scanning area inside a memory block */
 120 struct kmemleak_scan_area {
 121         struct hlist_node node;
 122         unsigned long start;
 123         size_t size;
 124 };
 125 
 126 #define KMEMLEAK_GREY   0
 127 #define KMEMLEAK_BLACK  -1
 128 
 129 /*
 130  * Structure holding the metadata for each allocated memory block.
 131  * Modifications to such objects should be made while holding the
 132  * object->lock. Insertions or deletions from object_list, gray_list or
 133  * rb_node are already protected by the corresponding locks or mutex (see
 134  * the notes on locking above). These objects are reference-counted
 135  * (use_count) and freed using the RCU mechanism.
 136  */
 137 struct kmemleak_object {
 138         spinlock_t lock;
 139         unsigned int flags;             /* object status flags */
 140         struct list_head object_list;
 141         struct list_head gray_list;
 142         struct rb_node rb_node;
 143         struct rcu_head rcu;            /* object_list lockless traversal */
 144         /* object usage count; object freed when use_count == 0 */
 145         atomic_t use_count;
 146         unsigned long pointer;
 147         size_t size;
 148         /* pass surplus references to this pointer */
 149         unsigned long excess_ref;
 150         /* minimum number of a pointers found before it is considered leak */
 151         int min_count;
 152         /* the total number of pointers found pointing to this object */
 153         int count;
 154         /* checksum for detecting modified objects */
 155         u32 checksum;
 156         /* memory ranges to be scanned inside an object (empty for all) */
 157         struct hlist_head area_list;
 158         unsigned long trace[MAX_TRACE];
 159         unsigned int trace_len;
 160         unsigned long jiffies;          /* creation timestamp */
 161         pid_t pid;                      /* pid of the current task */
 162         char comm[TASK_COMM_LEN];       /* executable name */
 163 };
 164 
 165 /* flag representing the memory block allocation status */
 166 #define OBJECT_ALLOCATED        (1 << 0)
 167 /* flag set after the first reporting of an unreference object */
 168 #define OBJECT_REPORTED         (1 << 1)
 169 /* flag set to not scan the object */
 170 #define OBJECT_NO_SCAN          (1 << 2)
 171 /* flag set to fully scan the object when scan_area allocation failed */
 172 #define OBJECT_FULL_SCAN        (1 << 3)
 173 
 174 #define HEX_PREFIX              "    "
 175 /* number of bytes to print per line; must be 16 or 32 */
 176 #define HEX_ROW_SIZE            16
 177 /* number of bytes to print at a time (1, 2, 4, 8) */
 178 #define HEX_GROUP_SIZE          1
 179 /* include ASCII after the hex output */
 180 #define HEX_ASCII               1
 181 /* max number of lines to be printed */
 182 #define HEX_MAX_LINES           2
 183 
 184 /* the list of all allocated objects */
 185 static LIST_HEAD(object_list);
 186 /* the list of gray-colored objects (see color_gray comment below) */
 187 static LIST_HEAD(gray_list);
 188 /* memory pool allocation */
 189 static struct kmemleak_object mem_pool[CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE];
 190 static int mem_pool_free_count = ARRAY_SIZE(mem_pool);
 191 static LIST_HEAD(mem_pool_free_list);
 192 /* search tree for object boundaries */
 193 static struct rb_root object_tree_root = RB_ROOT;
 194 /* rw_lock protecting the access to object_list and object_tree_root */
 195 static DEFINE_RWLOCK(kmemleak_lock);
 196 
 197 /* allocation caches for kmemleak internal data */
 198 static struct kmem_cache *object_cache;
 199 static struct kmem_cache *scan_area_cache;
 200 
 201 /* set if tracing memory operations is enabled */
 202 static int kmemleak_enabled = 1;
 203 /* same as above but only for the kmemleak_free() callback */
 204 static int kmemleak_free_enabled = 1;
 205 /* set in the late_initcall if there were no errors */
 206 static int kmemleak_initialized;
 207 /* set if a kmemleak warning was issued */
 208 static int kmemleak_warning;
 209 /* set if a fatal kmemleak error has occurred */
 210 static int kmemleak_error;
 211 
 212 /* minimum and maximum address that may be valid pointers */
 213 static unsigned long min_addr = ULONG_MAX;
 214 static unsigned long max_addr;
 215 
 216 static struct task_struct *scan_thread;
 217 /* used to avoid reporting of recently allocated objects */
 218 static unsigned long jiffies_min_age;
 219 static unsigned long jiffies_last_scan;
 220 /* delay between automatic memory scannings */
 221 static signed long jiffies_scan_wait;
 222 /* enables or disables the task stacks scanning */
 223 static int kmemleak_stack_scan = 1;
 224 /* protects the memory scanning, parameters and debug/kmemleak file access */
 225 static DEFINE_MUTEX(scan_mutex);
 226 /* setting kmemleak=on, will set this var, skipping the disable */
 227 static int kmemleak_skip_disable;
 228 /* If there are leaks that can be reported */
 229 static bool kmemleak_found_leaks;
 230 
 231 static bool kmemleak_verbose;
 232 module_param_named(verbose, kmemleak_verbose, bool, 0600);
 233 
 234 static void kmemleak_disable(void);
 235 
 236 /*
 237  * Print a warning and dump the stack trace.
 238  */
 239 #define kmemleak_warn(x...)     do {            \
 240         pr_warn(x);                             \
 241         dump_stack();                           \
 242         kmemleak_warning = 1;                   \
 243 } while (0)
 244 
 245 /*
 246  * Macro invoked when a serious kmemleak condition occurred and cannot be
 247  * recovered from. Kmemleak will be disabled and further allocation/freeing
 248  * tracing no longer available.
 249  */
 250 #define kmemleak_stop(x...)     do {    \
 251         kmemleak_warn(x);               \
 252         kmemleak_disable();             \
 253 } while (0)
 254 
 255 #define warn_or_seq_printf(seq, fmt, ...)       do {    \
 256         if (seq)                                        \
 257                 seq_printf(seq, fmt, ##__VA_ARGS__);    \
 258         else                                            \
 259                 pr_warn(fmt, ##__VA_ARGS__);            \
 260 } while (0)
 261 
 262 static void warn_or_seq_hex_dump(struct seq_file *seq, int prefix_type,
 263                                  int rowsize, int groupsize, const void *buf,
 264                                  size_t len, bool ascii)
 265 {
 266         if (seq)
 267                 seq_hex_dump(seq, HEX_PREFIX, prefix_type, rowsize, groupsize,
 268                              buf, len, ascii);
 269         else
 270                 print_hex_dump(KERN_WARNING, pr_fmt(HEX_PREFIX), prefix_type,
 271                                rowsize, groupsize, buf, len, ascii);
 272 }
 273 
 274 /*
 275  * Printing of the objects hex dump to the seq file. The number of lines to be
 276  * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
 277  * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
 278  * with the object->lock held.
 279  */
 280 static void hex_dump_object(struct seq_file *seq,
 281                             struct kmemleak_object *object)
 282 {
 283         const u8 *ptr = (const u8 *)object->pointer;
 284         size_t len;
 285 
 286         /* limit the number of lines to HEX_MAX_LINES */
 287         len = min_t(size_t, object->size, HEX_MAX_LINES * HEX_ROW_SIZE);
 288 
 289         warn_or_seq_printf(seq, "  hex dump (first %zu bytes):\n", len);
 290         kasan_disable_current();
 291         warn_or_seq_hex_dump(seq, DUMP_PREFIX_NONE, HEX_ROW_SIZE,
 292                              HEX_GROUP_SIZE, ptr, len, HEX_ASCII);
 293         kasan_enable_current();
 294 }
 295 
 296 /*
 297  * Object colors, encoded with count and min_count:
 298  * - white - orphan object, not enough references to it (count < min_count)
 299  * - gray  - not orphan, not marked as false positive (min_count == 0) or
 300  *              sufficient references to it (count >= min_count)
 301  * - black - ignore, it doesn't contain references (e.g. text section)
 302  *              (min_count == -1). No function defined for this color.
 303  * Newly created objects don't have any color assigned (object->count == -1)
 304  * before the next memory scan when they become white.
 305  */
 306 static bool color_white(const struct kmemleak_object *object)
 307 {
 308         return object->count != KMEMLEAK_BLACK &&
 309                 object->count < object->min_count;
 310 }
 311 
 312 static bool color_gray(const struct kmemleak_object *object)
 313 {
 314         return object->min_count != KMEMLEAK_BLACK &&
 315                 object->count >= object->min_count;
 316 }
 317 
 318 /*
 319  * Objects are considered unreferenced only if their color is white, they have
 320  * not be deleted and have a minimum age to avoid false positives caused by
 321  * pointers temporarily stored in CPU registers.
 322  */
 323 static bool unreferenced_object(struct kmemleak_object *object)
 324 {
 325         return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
 326                 time_before_eq(object->jiffies + jiffies_min_age,
 327                                jiffies_last_scan);
 328 }
 329 
 330 /*
 331  * Printing of the unreferenced objects information to the seq file. The
 332  * print_unreferenced function must be called with the object->lock held.
 333  */
 334 static void print_unreferenced(struct seq_file *seq,
 335                                struct kmemleak_object *object)
 336 {
 337         int i;
 338         unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
 339 
 340         warn_or_seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
 341                    object->pointer, object->size);
 342         warn_or_seq_printf(seq, "  comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
 343                    object->comm, object->pid, object->jiffies,
 344                    msecs_age / 1000, msecs_age % 1000);
 345         hex_dump_object(seq, object);
 346         warn_or_seq_printf(seq, "  backtrace:\n");
 347 
 348         for (i = 0; i < object->trace_len; i++) {
 349                 void *ptr = (void *)object->trace[i];
 350                 warn_or_seq_printf(seq, "    [<%p>] %pS\n", ptr, ptr);
 351         }
 352 }
 353 
 354 /*
 355  * Print the kmemleak_object information. This function is used mainly for
 356  * debugging special cases when kmemleak operations. It must be called with
 357  * the object->lock held.
 358  */
 359 static void dump_object_info(struct kmemleak_object *object)
 360 {
 361         pr_notice("Object 0x%08lx (size %zu):\n",
 362                   object->pointer, object->size);
 363         pr_notice("  comm \"%s\", pid %d, jiffies %lu\n",
 364                   object->comm, object->pid, object->jiffies);
 365         pr_notice("  min_count = %d\n", object->min_count);
 366         pr_notice("  count = %d\n", object->count);
 367         pr_notice("  flags = 0x%x\n", object->flags);
 368         pr_notice("  checksum = %u\n", object->checksum);
 369         pr_notice("  backtrace:\n");
 370         stack_trace_print(object->trace, object->trace_len, 4);
 371 }
 372 
 373 /*
 374  * Look-up a memory block metadata (kmemleak_object) in the object search
 375  * tree based on a pointer value. If alias is 0, only values pointing to the
 376  * beginning of the memory block are allowed. The kmemleak_lock must be held
 377  * when calling this function.
 378  */
 379 static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
 380 {
 381         struct rb_node *rb = object_tree_root.rb_node;
 382 
 383         while (rb) {
 384                 struct kmemleak_object *object =
 385                         rb_entry(rb, struct kmemleak_object, rb_node);
 386                 if (ptr < object->pointer)
 387                         rb = object->rb_node.rb_left;
 388                 else if (object->pointer + object->size <= ptr)
 389                         rb = object->rb_node.rb_right;
 390                 else if (object->pointer == ptr || alias)
 391                         return object;
 392                 else {
 393                         kmemleak_warn("Found object by alias at 0x%08lx\n",
 394                                       ptr);
 395                         dump_object_info(object);
 396                         break;
 397                 }
 398         }
 399         return NULL;
 400 }
 401 
 402 /*
 403  * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
 404  * that once an object's use_count reached 0, the RCU freeing was already
 405  * registered and the object should no longer be used. This function must be
 406  * called under the protection of rcu_read_lock().
 407  */
 408 static int get_object(struct kmemleak_object *object)
 409 {
 410         return atomic_inc_not_zero(&object->use_count);
 411 }
 412 
 413 /*
 414  * Memory pool allocation and freeing. kmemleak_lock must not be held.
 415  */
 416 static struct kmemleak_object *mem_pool_alloc(gfp_t gfp)
 417 {
 418         unsigned long flags;
 419         struct kmemleak_object *object;
 420 
 421         /* try the slab allocator first */
 422         if (object_cache) {
 423                 object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
 424                 if (object)
 425                         return object;
 426         }
 427 
 428         /* slab allocation failed, try the memory pool */
 429         write_lock_irqsave(&kmemleak_lock, flags);
 430         object = list_first_entry_or_null(&mem_pool_free_list,
 431                                           typeof(*object), object_list);
 432         if (object)
 433                 list_del(&object->object_list);
 434         else if (mem_pool_free_count)
 435                 object = &mem_pool[--mem_pool_free_count];
 436         else
 437                 pr_warn_once("Memory pool empty, consider increasing CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE\n");
 438         write_unlock_irqrestore(&kmemleak_lock, flags);
 439 
 440         return object;
 441 }
 442 
 443 /*
 444  * Return the object to either the slab allocator or the memory pool.
 445  */
 446 static void mem_pool_free(struct kmemleak_object *object)
 447 {
 448         unsigned long flags;
 449 
 450         if (object < mem_pool || object >= mem_pool + ARRAY_SIZE(mem_pool)) {
 451                 kmem_cache_free(object_cache, object);
 452                 return;
 453         }
 454 
 455         /* add the object to the memory pool free list */
 456         write_lock_irqsave(&kmemleak_lock, flags);
 457         list_add(&object->object_list, &mem_pool_free_list);
 458         write_unlock_irqrestore(&kmemleak_lock, flags);
 459 }
 460 
 461 /*
 462  * RCU callback to free a kmemleak_object.
 463  */
 464 static void free_object_rcu(struct rcu_head *rcu)
 465 {
 466         struct hlist_node *tmp;
 467         struct kmemleak_scan_area *area;
 468         struct kmemleak_object *object =
 469                 container_of(rcu, struct kmemleak_object, rcu);
 470 
 471         /*
 472          * Once use_count is 0 (guaranteed by put_object), there is no other
 473          * code accessing this object, hence no need for locking.
 474          */
 475         hlist_for_each_entry_safe(area, tmp, &object->area_list, node) {
 476                 hlist_del(&area->node);
 477                 kmem_cache_free(scan_area_cache, area);
 478         }
 479         mem_pool_free(object);
 480 }
 481 
 482 /*
 483  * Decrement the object use_count. Once the count is 0, free the object using
 484  * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
 485  * delete_object() path, the delayed RCU freeing ensures that there is no
 486  * recursive call to the kernel allocator. Lock-less RCU object_list traversal
 487  * is also possible.
 488  */
 489 static void put_object(struct kmemleak_object *object)
 490 {
 491         if (!atomic_dec_and_test(&object->use_count))
 492                 return;
 493 
 494         /* should only get here after delete_object was called */
 495         WARN_ON(object->flags & OBJECT_ALLOCATED);
 496 
 497         /*
 498          * It may be too early for the RCU callbacks, however, there is no
 499          * concurrent object_list traversal when !object_cache and all objects
 500          * came from the memory pool. Free the object directly.
 501          */
 502         if (object_cache)
 503                 call_rcu(&object->rcu, free_object_rcu);
 504         else
 505                 free_object_rcu(&object->rcu);
 506 }
 507 
 508 /*
 509  * Look up an object in the object search tree and increase its use_count.
 510  */
 511 static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
 512 {
 513         unsigned long flags;
 514         struct kmemleak_object *object;
 515 
 516         rcu_read_lock();
 517         read_lock_irqsave(&kmemleak_lock, flags);
 518         object = lookup_object(ptr, alias);
 519         read_unlock_irqrestore(&kmemleak_lock, flags);
 520 
 521         /* check whether the object is still available */
 522         if (object && !get_object(object))
 523                 object = NULL;
 524         rcu_read_unlock();
 525 
 526         return object;
 527 }
 528 
 529 /*
 530  * Remove an object from the object_tree_root and object_list. Must be called
 531  * with the kmemleak_lock held _if_ kmemleak is still enabled.
 532  */
 533 static void __remove_object(struct kmemleak_object *object)
 534 {
 535         rb_erase(&object->rb_node, &object_tree_root);
 536         list_del_rcu(&object->object_list);
 537 }
 538 
 539 /*
 540  * Look up an object in the object search tree and remove it from both
 541  * object_tree_root and object_list. The returned object's use_count should be
 542  * at least 1, as initially set by create_object().
 543  */
 544 static struct kmemleak_object *find_and_remove_object(unsigned long ptr, int alias)
 545 {
 546         unsigned long flags;
 547         struct kmemleak_object *object;
 548 
 549         write_lock_irqsave(&kmemleak_lock, flags);
 550         object = lookup_object(ptr, alias);
 551         if (object)
 552                 __remove_object(object);
 553         write_unlock_irqrestore(&kmemleak_lock, flags);
 554 
 555         return object;
 556 }
 557 
 558 /*
 559  * Save stack trace to the given array of MAX_TRACE size.
 560  */
 561 static int __save_stack_trace(unsigned long *trace)
 562 {
 563         return stack_trace_save(trace, MAX_TRACE, 2);
 564 }
 565 
 566 /*
 567  * Create the metadata (struct kmemleak_object) corresponding to an allocated
 568  * memory block and add it to the object_list and object_tree_root.
 569  */
 570 static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
 571                                              int min_count, gfp_t gfp)
 572 {
 573         unsigned long flags;
 574         struct kmemleak_object *object, *parent;
 575         struct rb_node **link, *rb_parent;
 576         unsigned long untagged_ptr;
 577 
 578         object = mem_pool_alloc(gfp);
 579         if (!object) {
 580                 pr_warn("Cannot allocate a kmemleak_object structure\n");
 581                 kmemleak_disable();
 582                 return NULL;
 583         }
 584 
 585         INIT_LIST_HEAD(&object->object_list);
 586         INIT_LIST_HEAD(&object->gray_list);
 587         INIT_HLIST_HEAD(&object->area_list);
 588         spin_lock_init(&object->lock);
 589         atomic_set(&object->use_count, 1);
 590         object->flags = OBJECT_ALLOCATED;
 591         object->pointer = ptr;
 592         object->size = size;
 593         object->excess_ref = 0;
 594         object->min_count = min_count;
 595         object->count = 0;                      /* white color initially */
 596         object->jiffies = jiffies;
 597         object->checksum = 0;
 598 
 599         /* task information */
 600         if (in_irq()) {
 601                 object->pid = 0;
 602                 strncpy(object->comm, "hardirq", sizeof(object->comm));
 603         } else if (in_serving_softirq()) {
 604                 object->pid = 0;
 605                 strncpy(object->comm, "softirq", sizeof(object->comm));
 606         } else {
 607                 object->pid = current->pid;
 608                 /*
 609                  * There is a small chance of a race with set_task_comm(),
 610                  * however using get_task_comm() here may cause locking
 611                  * dependency issues with current->alloc_lock. In the worst
 612                  * case, the command line is not correct.
 613                  */
 614                 strncpy(object->comm, current->comm, sizeof(object->comm));
 615         }
 616 
 617         /* kernel backtrace */
 618         object->trace_len = __save_stack_trace(object->trace);
 619 
 620         write_lock_irqsave(&kmemleak_lock, flags);
 621 
 622         untagged_ptr = (unsigned long)kasan_reset_tag((void *)ptr);
 623         min_addr = min(min_addr, untagged_ptr);
 624         max_addr = max(max_addr, untagged_ptr + size);
 625         link = &object_tree_root.rb_node;
 626         rb_parent = NULL;
 627         while (*link) {
 628                 rb_parent = *link;
 629                 parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
 630                 if (ptr + size <= parent->pointer)
 631                         link = &parent->rb_node.rb_left;
 632                 else if (parent->pointer + parent->size <= ptr)
 633                         link = &parent->rb_node.rb_right;
 634                 else {
 635                         kmemleak_stop("Cannot insert 0x%lx into the object search tree (overlaps existing)\n",
 636                                       ptr);
 637                         /*
 638                          * No need for parent->lock here since "parent" cannot
 639                          * be freed while the kmemleak_lock is held.
 640                          */
 641                         dump_object_info(parent);
 642                         kmem_cache_free(object_cache, object);
 643                         object = NULL;
 644                         goto out;
 645                 }
 646         }
 647         rb_link_node(&object->rb_node, rb_parent, link);
 648         rb_insert_color(&object->rb_node, &object_tree_root);
 649 
 650         list_add_tail_rcu(&object->object_list, &object_list);
 651 out:
 652         write_unlock_irqrestore(&kmemleak_lock, flags);
 653         return object;
 654 }
 655 
 656 /*
 657  * Mark the object as not allocated and schedule RCU freeing via put_object().
 658  */
 659 static void __delete_object(struct kmemleak_object *object)
 660 {
 661         unsigned long flags;
 662 
 663         WARN_ON(!(object->flags & OBJECT_ALLOCATED));
 664         WARN_ON(atomic_read(&object->use_count) < 1);
 665 
 666         /*
 667          * Locking here also ensures that the corresponding memory block
 668          * cannot be freed when it is being scanned.
 669          */
 670         spin_lock_irqsave(&object->lock, flags);
 671         object->flags &= ~OBJECT_ALLOCATED;
 672         spin_unlock_irqrestore(&object->lock, flags);
 673         put_object(object);
 674 }
 675 
 676 /*
 677  * Look up the metadata (struct kmemleak_object) corresponding to ptr and
 678  * delete it.
 679  */
 680 static void delete_object_full(unsigned long ptr)
 681 {
 682         struct kmemleak_object *object;
 683 
 684         object = find_and_remove_object(ptr, 0);
 685         if (!object) {
 686 #ifdef DEBUG
 687                 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
 688                               ptr);
 689 #endif
 690                 return;
 691         }
 692         __delete_object(object);
 693 }
 694 
 695 /*
 696  * Look up the metadata (struct kmemleak_object) corresponding to ptr and
 697  * delete it. If the memory block is partially freed, the function may create
 698  * additional metadata for the remaining parts of the block.
 699  */
 700 static void delete_object_part(unsigned long ptr, size_t size)
 701 {
 702         struct kmemleak_object *object;
 703         unsigned long start, end;
 704 
 705         object = find_and_remove_object(ptr, 1);
 706         if (!object) {
 707 #ifdef DEBUG
 708                 kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n",
 709                               ptr, size);
 710 #endif
 711                 return;
 712         }
 713 
 714         /*
 715          * Create one or two objects that may result from the memory block
 716          * split. Note that partial freeing is only done by free_bootmem() and
 717          * this happens before kmemleak_init() is called.
 718          */
 719         start = object->pointer;
 720         end = object->pointer + object->size;
 721         if (ptr > start)
 722                 create_object(start, ptr - start, object->min_count,
 723                               GFP_KERNEL);
 724         if (ptr + size < end)
 725                 create_object(ptr + size, end - ptr - size, object->min_count,
 726                               GFP_KERNEL);
 727 
 728         __delete_object(object);
 729 }
 730 
 731 static void __paint_it(struct kmemleak_object *object, int color)
 732 {
 733         object->min_count = color;
 734         if (color == KMEMLEAK_BLACK)
 735                 object->flags |= OBJECT_NO_SCAN;
 736 }
 737 
 738 static void paint_it(struct kmemleak_object *object, int color)
 739 {
 740         unsigned long flags;
 741 
 742         spin_lock_irqsave(&object->lock, flags);
 743         __paint_it(object, color);
 744         spin_unlock_irqrestore(&object->lock, flags);
 745 }
 746 
 747 static void paint_ptr(unsigned long ptr, int color)
 748 {
 749         struct kmemleak_object *object;
 750 
 751         object = find_and_get_object(ptr, 0);
 752         if (!object) {
 753                 kmemleak_warn("Trying to color unknown object at 0x%08lx as %s\n",
 754                               ptr,
 755                               (color == KMEMLEAK_GREY) ? "Grey" :
 756                               (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
 757                 return;
 758         }
 759         paint_it(object, color);
 760         put_object(object);
 761 }
 762 
 763 /*
 764  * Mark an object permanently as gray-colored so that it can no longer be
 765  * reported as a leak. This is used in general to mark a false positive.
 766  */
 767 static void make_gray_object(unsigned long ptr)
 768 {
 769         paint_ptr(ptr, KMEMLEAK_GREY);
 770 }
 771 
 772 /*
 773  * Mark the object as black-colored so that it is ignored from scans and
 774  * reporting.
 775  */
 776 static void make_black_object(unsigned long ptr)
 777 {
 778         paint_ptr(ptr, KMEMLEAK_BLACK);
 779 }
 780 
 781 /*
 782  * Add a scanning area to the object. If at least one such area is added,
 783  * kmemleak will only scan these ranges rather than the whole memory block.
 784  */
 785 static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
 786 {
 787         unsigned long flags;
 788         struct kmemleak_object *object;
 789         struct kmemleak_scan_area *area = NULL;
 790 
 791         object = find_and_get_object(ptr, 1);
 792         if (!object) {
 793                 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
 794                               ptr);
 795                 return;
 796         }
 797 
 798         if (scan_area_cache)
 799                 area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
 800 
 801         spin_lock_irqsave(&object->lock, flags);
 802         if (!area) {
 803                 pr_warn_once("Cannot allocate a scan area, scanning the full object\n");
 804                 /* mark the object for full scan to avoid false positives */
 805                 object->flags |= OBJECT_FULL_SCAN;
 806                 goto out_unlock;
 807         }
 808         if (size == SIZE_MAX) {
 809                 size = object->pointer + object->size - ptr;
 810         } else if (ptr + size > object->pointer + object->size) {
 811                 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
 812                 dump_object_info(object);
 813                 kmem_cache_free(scan_area_cache, area);
 814                 goto out_unlock;
 815         }
 816 
 817         INIT_HLIST_NODE(&area->node);
 818         area->start = ptr;
 819         area->size = size;
 820 
 821         hlist_add_head(&area->node, &object->area_list);
 822 out_unlock:
 823         spin_unlock_irqrestore(&object->lock, flags);
 824         put_object(object);
 825 }
 826 
 827 /*
 828  * Any surplus references (object already gray) to 'ptr' are passed to
 829  * 'excess_ref'. This is used in the vmalloc() case where a pointer to
 830  * vm_struct may be used as an alternative reference to the vmalloc'ed object
 831  * (see free_thread_stack()).
 832  */
 833 static void object_set_excess_ref(unsigned long ptr, unsigned long excess_ref)
 834 {
 835         unsigned long flags;
 836         struct kmemleak_object *object;
 837 
 838         object = find_and_get_object(ptr, 0);
 839         if (!object) {
 840                 kmemleak_warn("Setting excess_ref on unknown object at 0x%08lx\n",
 841                               ptr);
 842                 return;
 843         }
 844 
 845         spin_lock_irqsave(&object->lock, flags);
 846         object->excess_ref = excess_ref;
 847         spin_unlock_irqrestore(&object->lock, flags);
 848         put_object(object);
 849 }
 850 
 851 /*
 852  * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
 853  * pointer. Such object will not be scanned by kmemleak but references to it
 854  * are searched.
 855  */
 856 static void object_no_scan(unsigned long ptr)
 857 {
 858         unsigned long flags;
 859         struct kmemleak_object *object;
 860 
 861         object = find_and_get_object(ptr, 0);
 862         if (!object) {
 863                 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
 864                 return;
 865         }
 866 
 867         spin_lock_irqsave(&object->lock, flags);
 868         object->flags |= OBJECT_NO_SCAN;
 869         spin_unlock_irqrestore(&object->lock, flags);
 870         put_object(object);
 871 }
 872 
 873 /**
 874  * kmemleak_alloc - register a newly allocated object
 875  * @ptr:        pointer to beginning of the object
 876  * @size:       size of the object
 877  * @min_count:  minimum number of references to this object. If during memory
 878  *              scanning a number of references less than @min_count is found,
 879  *              the object is reported as a memory leak. If @min_count is 0,
 880  *              the object is never reported as a leak. If @min_count is -1,
 881  *              the object is ignored (not scanned and not reported as a leak)
 882  * @gfp:        kmalloc() flags used for kmemleak internal memory allocations
 883  *
 884  * This function is called from the kernel allocators when a new object
 885  * (memory block) is allocated (kmem_cache_alloc, kmalloc etc.).
 886  */
 887 void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
 888                           gfp_t gfp)
 889 {
 890         pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
 891 
 892         if (kmemleak_enabled && ptr && !IS_ERR(ptr))
 893                 create_object((unsigned long)ptr, size, min_count, gfp);
 894 }
 895 EXPORT_SYMBOL_GPL(kmemleak_alloc);
 896 
 897 /**
 898  * kmemleak_alloc_percpu - register a newly allocated __percpu object
 899  * @ptr:        __percpu pointer to beginning of the object
 900  * @size:       size of the object
 901  * @gfp:        flags used for kmemleak internal memory allocations
 902  *
 903  * This function is called from the kernel percpu allocator when a new object
 904  * (memory block) is allocated (alloc_percpu).
 905  */
 906 void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size,
 907                                  gfp_t gfp)
 908 {
 909         unsigned int cpu;
 910 
 911         pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
 912 
 913         /*
 914          * Percpu allocations are only scanned and not reported as leaks
 915          * (min_count is set to 0).
 916          */
 917         if (kmemleak_enabled && ptr && !IS_ERR(ptr))
 918                 for_each_possible_cpu(cpu)
 919                         create_object((unsigned long)per_cpu_ptr(ptr, cpu),
 920                                       size, 0, gfp);
 921 }
 922 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
 923 
 924 /**
 925  * kmemleak_vmalloc - register a newly vmalloc'ed object
 926  * @area:       pointer to vm_struct
 927  * @size:       size of the object
 928  * @gfp:        __vmalloc() flags used for kmemleak internal memory allocations
 929  *
 930  * This function is called from the vmalloc() kernel allocator when a new
 931  * object (memory block) is allocated.
 932  */
 933 void __ref kmemleak_vmalloc(const struct vm_struct *area, size_t size, gfp_t gfp)
 934 {
 935         pr_debug("%s(0x%p, %zu)\n", __func__, area, size);
 936 
 937         /*
 938          * A min_count = 2 is needed because vm_struct contains a reference to
 939          * the virtual address of the vmalloc'ed block.
 940          */
 941         if (kmemleak_enabled) {
 942                 create_object((unsigned long)area->addr, size, 2, gfp);
 943                 object_set_excess_ref((unsigned long)area,
 944                                       (unsigned long)area->addr);
 945         }
 946 }
 947 EXPORT_SYMBOL_GPL(kmemleak_vmalloc);
 948 
 949 /**
 950  * kmemleak_free - unregister a previously registered object
 951  * @ptr:        pointer to beginning of the object
 952  *
 953  * This function is called from the kernel allocators when an object (memory
 954  * block) is freed (kmem_cache_free, kfree, vfree etc.).
 955  */
 956 void __ref kmemleak_free(const void *ptr)
 957 {
 958         pr_debug("%s(0x%p)\n", __func__, ptr);
 959 
 960         if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
 961                 delete_object_full((unsigned long)ptr);
 962 }
 963 EXPORT_SYMBOL_GPL(kmemleak_free);
 964 
 965 /**
 966  * kmemleak_free_part - partially unregister a previously registered object
 967  * @ptr:        pointer to the beginning or inside the object. This also
 968  *              represents the start of the range to be freed
 969  * @size:       size to be unregistered
 970  *
 971  * This function is called when only a part of a memory block is freed
 972  * (usually from the bootmem allocator).
 973  */
 974 void __ref kmemleak_free_part(const void *ptr, size_t size)
 975 {
 976         pr_debug("%s(0x%p)\n", __func__, ptr);
 977 
 978         if (kmemleak_enabled && ptr && !IS_ERR(ptr))
 979                 delete_object_part((unsigned long)ptr, size);
 980 }
 981 EXPORT_SYMBOL_GPL(kmemleak_free_part);
 982 
 983 /**
 984  * kmemleak_free_percpu - unregister a previously registered __percpu object
 985  * @ptr:        __percpu pointer to beginning of the object
 986  *
 987  * This function is called from the kernel percpu allocator when an object
 988  * (memory block) is freed (free_percpu).
 989  */
 990 void __ref kmemleak_free_percpu(const void __percpu *ptr)
 991 {
 992         unsigned int cpu;
 993 
 994         pr_debug("%s(0x%p)\n", __func__, ptr);
 995 
 996         if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
 997                 for_each_possible_cpu(cpu)
 998                         delete_object_full((unsigned long)per_cpu_ptr(ptr,
 999                                                                       cpu));
1000 }
1001 EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
1002 
1003 /**
1004  * kmemleak_update_trace - update object allocation stack trace
1005  * @ptr:        pointer to beginning of the object
1006  *
1007  * Override the object allocation stack trace for cases where the actual
1008  * allocation place is not always useful.
1009  */
1010 void __ref kmemleak_update_trace(const void *ptr)
1011 {
1012         struct kmemleak_object *object;
1013         unsigned long flags;
1014 
1015         pr_debug("%s(0x%p)\n", __func__, ptr);
1016 
1017         if (!kmemleak_enabled || IS_ERR_OR_NULL(ptr))
1018                 return;
1019 
1020         object = find_and_get_object((unsigned long)ptr, 1);
1021         if (!object) {
1022 #ifdef DEBUG
1023                 kmemleak_warn("Updating stack trace for unknown object at %p\n",
1024                               ptr);
1025 #endif
1026                 return;
1027         }
1028 
1029         spin_lock_irqsave(&object->lock, flags);
1030         object->trace_len = __save_stack_trace(object->trace);
1031         spin_unlock_irqrestore(&object->lock, flags);
1032 
1033         put_object(object);
1034 }
1035 EXPORT_SYMBOL(kmemleak_update_trace);
1036 
1037 /**
1038  * kmemleak_not_leak - mark an allocated object as false positive
1039  * @ptr:        pointer to beginning of the object
1040  *
1041  * Calling this function on an object will cause the memory block to no longer
1042  * be reported as leak and always be scanned.
1043  */
1044 void __ref kmemleak_not_leak(const void *ptr)
1045 {
1046         pr_debug("%s(0x%p)\n", __func__, ptr);
1047 
1048         if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1049                 make_gray_object((unsigned long)ptr);
1050 }
1051 EXPORT_SYMBOL(kmemleak_not_leak);
1052 
1053 /**
1054  * kmemleak_ignore - ignore an allocated object
1055  * @ptr:        pointer to beginning of the object
1056  *
1057  * Calling this function on an object will cause the memory block to be
1058  * ignored (not scanned and not reported as a leak). This is usually done when
1059  * it is known that the corresponding block is not a leak and does not contain
1060  * any references to other allocated memory blocks.
1061  */
1062 void __ref kmemleak_ignore(const void *ptr)
1063 {
1064         pr_debug("%s(0x%p)\n", __func__, ptr);
1065 
1066         if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1067                 make_black_object((unsigned long)ptr);
1068 }
1069 EXPORT_SYMBOL(kmemleak_ignore);
1070 
1071 /**
1072  * kmemleak_scan_area - limit the range to be scanned in an allocated object
1073  * @ptr:        pointer to beginning or inside the object. This also
1074  *              represents the start of the scan area
1075  * @size:       size of the scan area
1076  * @gfp:        kmalloc() flags used for kmemleak internal memory allocations
1077  *
1078  * This function is used when it is known that only certain parts of an object
1079  * contain references to other objects. Kmemleak will only scan these areas
1080  * reducing the number false negatives.
1081  */
1082 void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
1083 {
1084         pr_debug("%s(0x%p)\n", __func__, ptr);
1085 
1086         if (kmemleak_enabled && ptr && size && !IS_ERR(ptr))
1087                 add_scan_area((unsigned long)ptr, size, gfp);
1088 }
1089 EXPORT_SYMBOL(kmemleak_scan_area);
1090 
1091 /**
1092  * kmemleak_no_scan - do not scan an allocated object
1093  * @ptr:        pointer to beginning of the object
1094  *
1095  * This function notifies kmemleak not to scan the given memory block. Useful
1096  * in situations where it is known that the given object does not contain any
1097  * references to other objects. Kmemleak will not scan such objects reducing
1098  * the number of false negatives.
1099  */
1100 void __ref kmemleak_no_scan(const void *ptr)
1101 {
1102         pr_debug("%s(0x%p)\n", __func__, ptr);
1103 
1104         if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1105                 object_no_scan((unsigned long)ptr);
1106 }
1107 EXPORT_SYMBOL(kmemleak_no_scan);
1108 
1109 /**
1110  * kmemleak_alloc_phys - similar to kmemleak_alloc but taking a physical
1111  *                       address argument
1112  * @phys:       physical address of the object
1113  * @size:       size of the object
1114  * @min_count:  minimum number of references to this object.
1115  *              See kmemleak_alloc()
1116  * @gfp:        kmalloc() flags used for kmemleak internal memory allocations
1117  */
1118 void __ref kmemleak_alloc_phys(phys_addr_t phys, size_t size, int min_count,
1119                                gfp_t gfp)
1120 {
1121         if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1122                 kmemleak_alloc(__va(phys), size, min_count, gfp);
1123 }
1124 EXPORT_SYMBOL(kmemleak_alloc_phys);
1125 
1126 /**
1127  * kmemleak_free_part_phys - similar to kmemleak_free_part but taking a
1128  *                           physical address argument
1129  * @phys:       physical address if the beginning or inside an object. This
1130  *              also represents the start of the range to be freed
1131  * @size:       size to be unregistered
1132  */
1133 void __ref kmemleak_free_part_phys(phys_addr_t phys, size_t size)
1134 {
1135         if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1136                 kmemleak_free_part(__va(phys), size);
1137 }
1138 EXPORT_SYMBOL(kmemleak_free_part_phys);
1139 
1140 /**
1141  * kmemleak_not_leak_phys - similar to kmemleak_not_leak but taking a physical
1142  *                          address argument
1143  * @phys:       physical address of the object
1144  */
1145 void __ref kmemleak_not_leak_phys(phys_addr_t phys)
1146 {
1147         if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1148                 kmemleak_not_leak(__va(phys));
1149 }
1150 EXPORT_SYMBOL(kmemleak_not_leak_phys);
1151 
1152 /**
1153  * kmemleak_ignore_phys - similar to kmemleak_ignore but taking a physical
1154  *                        address argument
1155  * @phys:       physical address of the object
1156  */
1157 void __ref kmemleak_ignore_phys(phys_addr_t phys)
1158 {
1159         if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1160                 kmemleak_ignore(__va(phys));
1161 }
1162 EXPORT_SYMBOL(kmemleak_ignore_phys);
1163 
1164 /*
1165  * Update an object's checksum and return true if it was modified.
1166  */
1167 static bool update_checksum(struct kmemleak_object *object)
1168 {
1169         u32 old_csum = object->checksum;
1170 
1171         kasan_disable_current();
1172         object->checksum = crc32(0, (void *)object->pointer, object->size);
1173         kasan_enable_current();
1174 
1175         return object->checksum != old_csum;
1176 }
1177 
1178 /*
1179  * Update an object's references. object->lock must be held by the caller.
1180  */
1181 static void update_refs(struct kmemleak_object *object)
1182 {
1183         if (!color_white(object)) {
1184                 /* non-orphan, ignored or new */
1185                 return;
1186         }
1187 
1188         /*
1189          * Increase the object's reference count (number of pointers to the
1190          * memory block). If this count reaches the required minimum, the
1191          * object's color will become gray and it will be added to the
1192          * gray_list.
1193          */
1194         object->count++;
1195         if (color_gray(object)) {
1196                 /* put_object() called when removing from gray_list */
1197                 WARN_ON(!get_object(object));
1198                 list_add_tail(&object->gray_list, &gray_list);
1199         }
1200 }
1201 
1202 /*
1203  * Memory scanning is a long process and it needs to be interruptable. This
1204  * function checks whether such interrupt condition occurred.
1205  */
1206 static int scan_should_stop(void)
1207 {
1208         if (!kmemleak_enabled)
1209                 return 1;
1210 
1211         /*
1212          * This function may be called from either process or kthread context,
1213          * hence the need to check for both stop conditions.
1214          */
1215         if (current->mm)
1216                 return signal_pending(current);
1217         else
1218                 return kthread_should_stop();
1219 
1220         return 0;
1221 }
1222 
1223 /*
1224  * Scan a memory block (exclusive range) for valid pointers and add those
1225  * found to the gray list.
1226  */
1227 static void scan_block(void *_start, void *_end,
1228                        struct kmemleak_object *scanned)
1229 {
1230         unsigned long *ptr;
1231         unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1232         unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1233         unsigned long flags;
1234         unsigned long untagged_ptr;
1235 
1236         read_lock_irqsave(&kmemleak_lock, flags);
1237         for (ptr = start; ptr < end; ptr++) {
1238                 struct kmemleak_object *object;
1239                 unsigned long pointer;
1240                 unsigned long excess_ref;
1241 
1242                 if (scan_should_stop())
1243                         break;
1244 
1245                 kasan_disable_current();
1246                 pointer = *ptr;
1247                 kasan_enable_current();
1248 
1249                 untagged_ptr = (unsigned long)kasan_reset_tag((void *)pointer);
1250                 if (untagged_ptr < min_addr || untagged_ptr >= max_addr)
1251                         continue;
1252 
1253                 /*
1254                  * No need for get_object() here since we hold kmemleak_lock.
1255                  * object->use_count cannot be dropped to 0 while the object
1256                  * is still present in object_tree_root and object_list
1257                  * (with updates protected by kmemleak_lock).
1258                  */
1259                 object = lookup_object(pointer, 1);
1260                 if (!object)
1261                         continue;
1262                 if (object == scanned)
1263                         /* self referenced, ignore */
1264                         continue;
1265 
1266                 /*
1267                  * Avoid the lockdep recursive warning on object->lock being
1268                  * previously acquired in scan_object(). These locks are
1269                  * enclosed by scan_mutex.
1270                  */
1271                 spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
1272                 /* only pass surplus references (object already gray) */
1273                 if (color_gray(object)) {
1274                         excess_ref = object->excess_ref;
1275                         /* no need for update_refs() if object already gray */
1276                 } else {
1277                         excess_ref = 0;
1278                         update_refs(object);
1279                 }
1280                 spin_unlock(&object->lock);
1281 
1282                 if (excess_ref) {
1283                         object = lookup_object(excess_ref, 0);
1284                         if (!object)
1285                                 continue;
1286                         if (object == scanned)
1287                                 /* circular reference, ignore */
1288                                 continue;
1289                         spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
1290                         update_refs(object);
1291                         spin_unlock(&object->lock);
1292                 }
1293         }
1294         read_unlock_irqrestore(&kmemleak_lock, flags);
1295 }
1296 
1297 /*
1298  * Scan a large memory block in MAX_SCAN_SIZE chunks to reduce the latency.
1299  */
1300 #ifdef CONFIG_SMP
1301 static void scan_large_block(void *start, void *end)
1302 {
1303         void *next;
1304 
1305         while (start < end) {
1306                 next = min(start + MAX_SCAN_SIZE, end);
1307                 scan_block(start, next, NULL);
1308                 start = next;
1309                 cond_resched();
1310         }
1311 }
1312 #endif
1313 
1314 /*
1315  * Scan a memory block corresponding to a kmemleak_object. A condition is
1316  * that object->use_count >= 1.
1317  */
1318 static void scan_object(struct kmemleak_object *object)
1319 {
1320         struct kmemleak_scan_area *area;
1321         unsigned long flags;
1322 
1323         /*
1324          * Once the object->lock is acquired, the corresponding memory block
1325          * cannot be freed (the same lock is acquired in delete_object).
1326          */
1327         spin_lock_irqsave(&object->lock, flags);
1328         if (object->flags & OBJECT_NO_SCAN)
1329                 goto out;
1330         if (!(object->flags & OBJECT_ALLOCATED))
1331                 /* already freed object */
1332                 goto out;
1333         if (hlist_empty(&object->area_list) ||
1334             object->flags & OBJECT_FULL_SCAN) {
1335                 void *start = (void *)object->pointer;
1336                 void *end = (void *)(object->pointer + object->size);
1337                 void *next;
1338 
1339                 do {
1340                         next = min(start + MAX_SCAN_SIZE, end);
1341                         scan_block(start, next, object);
1342 
1343                         start = next;
1344                         if (start >= end)
1345                                 break;
1346 
1347                         spin_unlock_irqrestore(&object->lock, flags);
1348                         cond_resched();
1349                         spin_lock_irqsave(&object->lock, flags);
1350                 } while (object->flags & OBJECT_ALLOCATED);
1351         } else
1352                 hlist_for_each_entry(area, &object->area_list, node)
1353                         scan_block((void *)area->start,
1354                                    (void *)(area->start + area->size),
1355                                    object);
1356 out:
1357         spin_unlock_irqrestore(&object->lock, flags);
1358 }
1359 
1360 /*
1361  * Scan the objects already referenced (gray objects). More objects will be
1362  * referenced and, if there are no memory leaks, all the objects are scanned.
1363  */
1364 static void scan_gray_list(void)
1365 {
1366         struct kmemleak_object *object, *tmp;
1367 
1368         /*
1369          * The list traversal is safe for both tail additions and removals
1370          * from inside the loop. The kmemleak objects cannot be freed from
1371          * outside the loop because their use_count was incremented.
1372          */
1373         object = list_entry(gray_list.next, typeof(*object), gray_list);
1374         while (&object->gray_list != &gray_list) {
1375                 cond_resched();
1376 
1377                 /* may add new objects to the list */
1378                 if (!scan_should_stop())
1379                         scan_object(object);
1380 
1381                 tmp = list_entry(object->gray_list.next, typeof(*object),
1382                                  gray_list);
1383 
1384                 /* remove the object from the list and release it */
1385                 list_del(&object->gray_list);
1386                 put_object(object);
1387 
1388                 object = tmp;
1389         }
1390         WARN_ON(!list_empty(&gray_list));
1391 }
1392 
1393 /*
1394  * Scan data sections and all the referenced memory blocks allocated via the
1395  * kernel's standard allocators. This function must be called with the
1396  * scan_mutex held.
1397  */
1398 static void kmemleak_scan(void)
1399 {
1400         unsigned long flags;
1401         struct kmemleak_object *object;
1402         int i;
1403         int new_leaks = 0;
1404 
1405         jiffies_last_scan = jiffies;
1406 
1407         /* prepare the kmemleak_object's */
1408         rcu_read_lock();
1409         list_for_each_entry_rcu(object, &object_list, object_list) {
1410                 spin_lock_irqsave(&object->lock, flags);
1411 #ifdef DEBUG
1412                 /*
1413                  * With a few exceptions there should be a maximum of
1414                  * 1 reference to any object at this point.
1415                  */
1416                 if (atomic_read(&object->use_count) > 1) {
1417                         pr_debug("object->use_count = %d\n",
1418                                  atomic_read(&object->use_count));
1419                         dump_object_info(object);
1420                 }
1421 #endif
1422                 /* reset the reference count (whiten the object) */
1423                 object->count = 0;
1424                 if (color_gray(object) && get_object(object))
1425                         list_add_tail(&object->gray_list, &gray_list);
1426 
1427                 spin_unlock_irqrestore(&object->lock, flags);
1428         }
1429         rcu_read_unlock();
1430 
1431 #ifdef CONFIG_SMP
1432         /* per-cpu sections scanning */
1433         for_each_possible_cpu(i)
1434                 scan_large_block(__per_cpu_start + per_cpu_offset(i),
1435                                  __per_cpu_end + per_cpu_offset(i));
1436 #endif
1437 
1438         /*
1439          * Struct page scanning for each node.
1440          */
1441         get_online_mems();
1442         for_each_online_node(i) {
1443                 unsigned long start_pfn = node_start_pfn(i);
1444                 unsigned long end_pfn = node_end_pfn(i);
1445                 unsigned long pfn;
1446 
1447                 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1448                         struct page *page = pfn_to_online_page(pfn);
1449 
1450                         if (!page)
1451                                 continue;
1452 
1453                         /* only scan pages belonging to this node */
1454                         if (page_to_nid(page) != i)
1455                                 continue;
1456                         /* only scan if page is in use */
1457                         if (page_count(page) == 0)
1458                                 continue;
1459                         scan_block(page, page + 1, NULL);
1460                         if (!(pfn & 63))
1461                                 cond_resched();
1462                 }
1463         }
1464         put_online_mems();
1465 
1466         /*
1467          * Scanning the task stacks (may introduce false negatives).
1468          */
1469         if (kmemleak_stack_scan) {
1470                 struct task_struct *p, *g;
1471 
1472                 read_lock(&tasklist_lock);
1473                 do_each_thread(g, p) {
1474                         void *stack = try_get_task_stack(p);
1475                         if (stack) {
1476                                 scan_block(stack, stack + THREAD_SIZE, NULL);
1477                                 put_task_stack(p);
1478                         }
1479                 } while_each_thread(g, p);
1480                 read_unlock(&tasklist_lock);
1481         }
1482 
1483         /*
1484          * Scan the objects already referenced from the sections scanned
1485          * above.
1486          */
1487         scan_gray_list();
1488 
1489         /*
1490          * Check for new or unreferenced objects modified since the previous
1491          * scan and color them gray until the next scan.
1492          */
1493         rcu_read_lock();
1494         list_for_each_entry_rcu(object, &object_list, object_list) {
1495                 spin_lock_irqsave(&object->lock, flags);
1496                 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1497                     && update_checksum(object) && get_object(object)) {
1498                         /* color it gray temporarily */
1499                         object->count = object->min_count;
1500                         list_add_tail(&object->gray_list, &gray_list);
1501                 }
1502                 spin_unlock_irqrestore(&object->lock, flags);
1503         }
1504         rcu_read_unlock();
1505 
1506         /*
1507          * Re-scan the gray list for modified unreferenced objects.
1508          */
1509         scan_gray_list();
1510 
1511         /*
1512          * If scanning was stopped do not report any new unreferenced objects.
1513          */
1514         if (scan_should_stop())
1515                 return;
1516 
1517         /*
1518          * Scanning result reporting.
1519          */
1520         rcu_read_lock();
1521         list_for_each_entry_rcu(object, &object_list, object_list) {
1522                 spin_lock_irqsave(&object->lock, flags);
1523                 if (unreferenced_object(object) &&
1524                     !(object->flags & OBJECT_REPORTED)) {
1525                         object->flags |= OBJECT_REPORTED;
1526 
1527                         if (kmemleak_verbose)
1528                                 print_unreferenced(NULL, object);
1529 
1530                         new_leaks++;
1531                 }
1532                 spin_unlock_irqrestore(&object->lock, flags);
1533         }
1534         rcu_read_unlock();
1535 
1536         if (new_leaks) {
1537                 kmemleak_found_leaks = true;
1538 
1539                 pr_info("%d new suspected memory leaks (see /sys/kernel/debug/kmemleak)\n",
1540                         new_leaks);
1541         }
1542 
1543 }
1544 
1545 /*
1546  * Thread function performing automatic memory scanning. Unreferenced objects
1547  * at the end of a memory scan are reported but only the first time.
1548  */
1549 static int kmemleak_scan_thread(void *arg)
1550 {
1551         static int first_run = IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN);
1552 
1553         pr_info("Automatic memory scanning thread started\n");
1554         set_user_nice(current, 10);
1555 
1556         /*
1557          * Wait before the first scan to allow the system to fully initialize.
1558          */
1559         if (first_run) {
1560                 signed long timeout = msecs_to_jiffies(SECS_FIRST_SCAN * 1000);
1561                 first_run = 0;
1562                 while (timeout && !kthread_should_stop())
1563                         timeout = schedule_timeout_interruptible(timeout);
1564         }
1565 
1566         while (!kthread_should_stop()) {
1567                 signed long timeout = jiffies_scan_wait;
1568 
1569                 mutex_lock(&scan_mutex);
1570                 kmemleak_scan();
1571                 mutex_unlock(&scan_mutex);
1572 
1573                 /* wait before the next scan */
1574                 while (timeout && !kthread_should_stop())
1575                         timeout = schedule_timeout_interruptible(timeout);
1576         }
1577 
1578         pr_info("Automatic memory scanning thread ended\n");
1579 
1580         return 0;
1581 }
1582 
1583 /*
1584  * Start the automatic memory scanning thread. This function must be called
1585  * with the scan_mutex held.
1586  */
1587 static void start_scan_thread(void)
1588 {
1589         if (scan_thread)
1590                 return;
1591         scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1592         if (IS_ERR(scan_thread)) {
1593                 pr_warn("Failed to create the scan thread\n");
1594                 scan_thread = NULL;
1595         }
1596 }
1597 
1598 /*
1599  * Stop the automatic memory scanning thread.
1600  */
1601 static void stop_scan_thread(void)
1602 {
1603         if (scan_thread) {
1604                 kthread_stop(scan_thread);
1605                 scan_thread = NULL;
1606         }
1607 }
1608 
1609 /*
1610  * Iterate over the object_list and return the first valid object at or after
1611  * the required position with its use_count incremented. The function triggers
1612  * a memory scanning when the pos argument points to the first position.
1613  */
1614 static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1615 {
1616         struct kmemleak_object *object;
1617         loff_t n = *pos;
1618         int err;
1619 
1620         err = mutex_lock_interruptible(&scan_mutex);
1621         if (err < 0)
1622                 return ERR_PTR(err);
1623 
1624         rcu_read_lock();
1625         list_for_each_entry_rcu(object, &object_list, object_list) {
1626                 if (n-- > 0)
1627                         continue;
1628                 if (get_object(object))
1629                         goto out;
1630         }
1631         object = NULL;
1632 out:
1633         return object;
1634 }
1635 
1636 /*
1637  * Return the next object in the object_list. The function decrements the
1638  * use_count of the previous object and increases that of the next one.
1639  */
1640 static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1641 {
1642         struct kmemleak_object *prev_obj = v;
1643         struct kmemleak_object *next_obj = NULL;
1644         struct kmemleak_object *obj = prev_obj;
1645 
1646         ++(*pos);
1647 
1648         list_for_each_entry_continue_rcu(obj, &object_list, object_list) {
1649                 if (get_object(obj)) {
1650                         next_obj = obj;
1651                         break;
1652                 }
1653         }
1654 
1655         put_object(prev_obj);
1656         return next_obj;
1657 }
1658 
1659 /*
1660  * Decrement the use_count of the last object required, if any.
1661  */
1662 static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1663 {
1664         if (!IS_ERR(v)) {
1665                 /*
1666                  * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1667                  * waiting was interrupted, so only release it if !IS_ERR.
1668                  */
1669                 rcu_read_unlock();
1670                 mutex_unlock(&scan_mutex);
1671                 if (v)
1672                         put_object(v);
1673         }
1674 }
1675 
1676 /*
1677  * Print the information for an unreferenced object to the seq file.
1678  */
1679 static int kmemleak_seq_show(struct seq_file *seq, void *v)
1680 {
1681         struct kmemleak_object *object = v;
1682         unsigned long flags;
1683 
1684         spin_lock_irqsave(&object->lock, flags);
1685         if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
1686                 print_unreferenced(seq, object);
1687         spin_unlock_irqrestore(&object->lock, flags);
1688         return 0;
1689 }
1690 
1691 static const struct seq_operations kmemleak_seq_ops = {
1692         .start = kmemleak_seq_start,
1693         .next  = kmemleak_seq_next,
1694         .stop  = kmemleak_seq_stop,
1695         .show  = kmemleak_seq_show,
1696 };
1697 
1698 static int kmemleak_open(struct inode *inode, struct file *file)
1699 {
1700         return seq_open(file, &kmemleak_seq_ops);
1701 }
1702 
1703 static int dump_str_object_info(const char *str)
1704 {
1705         unsigned long flags;
1706         struct kmemleak_object *object;
1707         unsigned long addr;
1708 
1709         if (kstrtoul(str, 0, &addr))
1710                 return -EINVAL;
1711         object = find_and_get_object(addr, 0);
1712         if (!object) {
1713                 pr_info("Unknown object at 0x%08lx\n", addr);
1714                 return -EINVAL;
1715         }
1716 
1717         spin_lock_irqsave(&object->lock, flags);
1718         dump_object_info(object);
1719         spin_unlock_irqrestore(&object->lock, flags);
1720 
1721         put_object(object);
1722         return 0;
1723 }
1724 
1725 /*
1726  * We use grey instead of black to ensure we can do future scans on the same
1727  * objects. If we did not do future scans these black objects could
1728  * potentially contain references to newly allocated objects in the future and
1729  * we'd end up with false positives.
1730  */
1731 static void kmemleak_clear(void)
1732 {
1733         struct kmemleak_object *object;
1734         unsigned long flags;
1735 
1736         rcu_read_lock();
1737         list_for_each_entry_rcu(object, &object_list, object_list) {
1738                 spin_lock_irqsave(&object->lock, flags);
1739                 if ((object->flags & OBJECT_REPORTED) &&
1740                     unreferenced_object(object))
1741                         __paint_it(object, KMEMLEAK_GREY);
1742                 spin_unlock_irqrestore(&object->lock, flags);
1743         }
1744         rcu_read_unlock();
1745 
1746         kmemleak_found_leaks = false;
1747 }
1748 
1749 static void __kmemleak_do_cleanup(void);
1750 
1751 /*
1752  * File write operation to configure kmemleak at run-time. The following
1753  * commands can be written to the /sys/kernel/debug/kmemleak file:
1754  *   off        - disable kmemleak (irreversible)
1755  *   stack=on   - enable the task stacks scanning
1756  *   stack=off  - disable the tasks stacks scanning
1757  *   scan=on    - start the automatic memory scanning thread
1758  *   scan=off   - stop the automatic memory scanning thread
1759  *   scan=...   - set the automatic memory scanning period in seconds (0 to
1760  *                disable it)
1761  *   scan       - trigger a memory scan
1762  *   clear      - mark all current reported unreferenced kmemleak objects as
1763  *                grey to ignore printing them, or free all kmemleak objects
1764  *                if kmemleak has been disabled.
1765  *   dump=...   - dump information about the object found at the given address
1766  */
1767 static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1768                               size_t size, loff_t *ppos)
1769 {
1770         char buf[64];
1771         int buf_size;
1772         int ret;
1773 
1774         buf_size = min(size, (sizeof(buf) - 1));
1775         if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1776                 return -EFAULT;
1777         buf[buf_size] = 0;
1778 
1779         ret = mutex_lock_interruptible(&scan_mutex);
1780         if (ret < 0)
1781                 return ret;
1782 
1783         if (strncmp(buf, "clear", 5) == 0) {
1784                 if (kmemleak_enabled)
1785                         kmemleak_clear();
1786                 else
1787                         __kmemleak_do_cleanup();
1788                 goto out;
1789         }
1790 
1791         if (!kmemleak_enabled) {
1792                 ret = -EPERM;
1793                 goto out;
1794         }
1795 
1796         if (strncmp(buf, "off", 3) == 0)
1797                 kmemleak_disable();
1798         else if (strncmp(buf, "stack=on", 8) == 0)
1799                 kmemleak_stack_scan = 1;
1800         else if (strncmp(buf, "stack=off", 9) == 0)
1801                 kmemleak_stack_scan = 0;
1802         else if (strncmp(buf, "scan=on", 7) == 0)
1803                 start_scan_thread();
1804         else if (strncmp(buf, "scan=off", 8) == 0)
1805                 stop_scan_thread();
1806         else if (strncmp(buf, "scan=", 5) == 0) {
1807                 unsigned long secs;
1808 
1809                 ret = kstrtoul(buf + 5, 0, &secs);
1810                 if (ret < 0)
1811                         goto out;
1812                 stop_scan_thread();
1813                 if (secs) {
1814                         jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1815                         start_scan_thread();
1816                 }
1817         } else if (strncmp(buf, "scan", 4) == 0)
1818                 kmemleak_scan();
1819         else if (strncmp(buf, "dump=", 5) == 0)
1820                 ret = dump_str_object_info(buf + 5);
1821         else
1822                 ret = -EINVAL;
1823 
1824 out:
1825         mutex_unlock(&scan_mutex);
1826         if (ret < 0)
1827                 return ret;
1828 
1829         /* ignore the rest of the buffer, only one command at a time */
1830         *ppos += size;
1831         return size;
1832 }
1833 
1834 static const struct file_operations kmemleak_fops = {
1835         .owner          = THIS_MODULE,
1836         .open           = kmemleak_open,
1837         .read           = seq_read,
1838         .write          = kmemleak_write,
1839         .llseek         = seq_lseek,
1840         .release        = seq_release,
1841 };
1842 
1843 static void __kmemleak_do_cleanup(void)
1844 {
1845         struct kmemleak_object *object, *tmp;
1846 
1847         /*
1848          * Kmemleak has already been disabled, no need for RCU list traversal
1849          * or kmemleak_lock held.
1850          */
1851         list_for_each_entry_safe(object, tmp, &object_list, object_list) {
1852                 __remove_object(object);
1853                 __delete_object(object);
1854         }
1855 }
1856 
1857 /*
1858  * Stop the memory scanning thread and free the kmemleak internal objects if
1859  * no previous scan thread (otherwise, kmemleak may still have some useful
1860  * information on memory leaks).
1861  */
1862 static void kmemleak_do_cleanup(struct work_struct *work)
1863 {
1864         stop_scan_thread();
1865 
1866         mutex_lock(&scan_mutex);
1867         /*
1868          * Once it is made sure that kmemleak_scan has stopped, it is safe to no
1869          * longer track object freeing. Ordering of the scan thread stopping and
1870          * the memory accesses below is guaranteed by the kthread_stop()
1871          * function.
1872          */
1873         kmemleak_free_enabled = 0;
1874         mutex_unlock(&scan_mutex);
1875 
1876         if (!kmemleak_found_leaks)
1877                 __kmemleak_do_cleanup();
1878         else
1879                 pr_info("Kmemleak disabled without freeing internal data. Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\".\n");
1880 }
1881 
1882 static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
1883 
1884 /*
1885  * Disable kmemleak. No memory allocation/freeing will be traced once this
1886  * function is called. Disabling kmemleak is an irreversible operation.
1887  */
1888 static void kmemleak_disable(void)
1889 {
1890         /* atomically check whether it was already invoked */
1891         if (cmpxchg(&kmemleak_error, 0, 1))
1892                 return;
1893 
1894         /* stop any memory operation tracing */
1895         kmemleak_enabled = 0;
1896 
1897         /* check whether it is too early for a kernel thread */
1898         if (kmemleak_initialized)
1899                 schedule_work(&cleanup_work);
1900         else
1901                 kmemleak_free_enabled = 0;
1902 
1903         pr_info("Kernel memory leak detector disabled\n");
1904 }
1905 
1906 /*
1907  * Allow boot-time kmemleak disabling (enabled by default).
1908  */
1909 static int __init kmemleak_boot_config(char *str)
1910 {
1911         if (!str)
1912                 return -EINVAL;
1913         if (strcmp(str, "off") == 0)
1914                 kmemleak_disable();
1915         else if (strcmp(str, "on") == 0)
1916                 kmemleak_skip_disable = 1;
1917         else
1918                 return -EINVAL;
1919         return 0;
1920 }
1921 early_param("kmemleak", kmemleak_boot_config);
1922 
1923 /*
1924  * Kmemleak initialization.
1925  */
1926 void __init kmemleak_init(void)
1927 {
1928 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1929         if (!kmemleak_skip_disable) {
1930                 kmemleak_disable();
1931                 return;
1932         }
1933 #endif
1934 
1935         if (kmemleak_error)
1936                 return;
1937 
1938         jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1939         jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1940 
1941         object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1942         scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1943 
1944         /* register the data/bss sections */
1945         create_object((unsigned long)_sdata, _edata - _sdata,
1946                       KMEMLEAK_GREY, GFP_ATOMIC);
1947         create_object((unsigned long)__bss_start, __bss_stop - __bss_start,
1948                       KMEMLEAK_GREY, GFP_ATOMIC);
1949         /* only register .data..ro_after_init if not within .data */
1950         if (__start_ro_after_init < _sdata || __end_ro_after_init > _edata)
1951                 create_object((unsigned long)__start_ro_after_init,
1952                               __end_ro_after_init - __start_ro_after_init,
1953                               KMEMLEAK_GREY, GFP_ATOMIC);
1954 }
1955 
1956 /*
1957  * Late initialization function.
1958  */
1959 static int __init kmemleak_late_init(void)
1960 {
1961         kmemleak_initialized = 1;
1962 
1963         debugfs_create_file("kmemleak", 0644, NULL, NULL, &kmemleak_fops);
1964 
1965         if (kmemleak_error) {
1966                 /*
1967                  * Some error occurred and kmemleak was disabled. There is a
1968                  * small chance that kmemleak_disable() was called immediately
1969                  * after setting kmemleak_initialized and we may end up with
1970                  * two clean-up threads but serialized by scan_mutex.
1971                  */
1972                 schedule_work(&cleanup_work);
1973                 return -ENOMEM;
1974         }
1975 
1976         if (IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN)) {
1977                 mutex_lock(&scan_mutex);
1978                 start_scan_thread();
1979                 mutex_unlock(&scan_mutex);
1980         }
1981 
1982         pr_info("Kernel memory leak detector initialized (mem pool available: %d)\n",
1983                 mem_pool_free_count);
1984 
1985         return 0;
1986 }
1987 late_initcall(kmemleak_late_init);