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 (raw_spinlock_t): 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 (raw_spinlock_t): protects a kmemleak_object.
  26 *   Accesses to the metadata (e.g. count) are protected by this lock. Note
  27 *   that some members of this structure may be protected by other means
  28 *   (atomic or kmemleak_lock). This lock is also held when scanning the
  29 *   corresponding memory block to avoid the kernel freeing it via the
  30 *   kmemleak_free() callback. This is less heavyweight than holding a global
  31 *   lock like 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/kfence.h>
 101#include <linux/kmemleak.h>
 102#include <linux/memory_hotplug.h>
 103
 104/*
 105 * Kmemleak configuration and common defines.
 106 */
 107#define MAX_TRACE		16	/* stack trace length */
 108#define MSECS_MIN_AGE		5000	/* minimum object age for reporting */
 109#define SECS_FIRST_SCAN		60	/* delay before the first scan */
 110#define SECS_SCAN_WAIT		600	/* subsequent auto scanning delay */
 111#define MAX_SCAN_SIZE		4096	/* maximum size of a scanned block */
 112
 113#define BYTES_PER_POINTER	sizeof(void *)
 114
 115/* GFP bitmask for kmemleak internal allocations */
 116#define gfp_kmemleak_mask(gfp)	(((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
 117				 __GFP_NORETRY | __GFP_NOMEMALLOC | \
 118				 __GFP_NOWARN)
 119
 120/* scanning area inside a memory block */
 121struct kmemleak_scan_area {
 122	struct hlist_node node;
 123	unsigned long start;
 124	size_t size;
 125};
 126
 127#define KMEMLEAK_GREY	0
 128#define KMEMLEAK_BLACK	-1
 129
 130/*
 131 * Structure holding the metadata for each allocated memory block.
 132 * Modifications to such objects should be made while holding the
 133 * object->lock. Insertions or deletions from object_list, gray_list or
 134 * rb_node are already protected by the corresponding locks or mutex (see
 135 * the notes on locking above). These objects are reference-counted
 136 * (use_count) and freed using the RCU mechanism.
 137 */
 138struct kmemleak_object {
 139	raw_spinlock_t lock;
 140	unsigned int flags;		/* object status flags */
 141	struct list_head object_list;
 142	struct list_head gray_list;
 143	struct rb_node rb_node;
 144	struct rcu_head rcu;		/* object_list lockless traversal */
 145	/* object usage count; object freed when use_count == 0 */
 146	atomic_t use_count;
 147	unsigned long pointer;
 148	size_t size;
 149	/* pass surplus references to this pointer */
 150	unsigned long excess_ref;
 151	/* minimum number of a pointers found before it is considered leak */
 152	int min_count;
 153	/* the total number of pointers found pointing to this object */
 154	int count;
 155	/* checksum for detecting modified objects */
 156	u32 checksum;
 157	/* memory ranges to be scanned inside an object (empty for all) */
 158	struct hlist_head area_list;
 159	unsigned long trace[MAX_TRACE];
 160	unsigned int trace_len;
 161	unsigned long jiffies;		/* creation timestamp */
 162	pid_t pid;			/* pid of the current task */
 163	char comm[TASK_COMM_LEN];	/* executable name */
 164};
 165
 166/* flag representing the memory block allocation status */
 167#define OBJECT_ALLOCATED	(1 << 0)
 168/* flag set after the first reporting of an unreference object */
 169#define OBJECT_REPORTED		(1 << 1)
 170/* flag set to not scan the object */
 171#define OBJECT_NO_SCAN		(1 << 2)
 172/* flag set to fully scan the object when scan_area allocation failed */
 173#define OBJECT_FULL_SCAN	(1 << 3)
 174
 175#define HEX_PREFIX		"    "
 176/* number of bytes to print per line; must be 16 or 32 */
 177#define HEX_ROW_SIZE		16
 178/* number of bytes to print at a time (1, 2, 4, 8) */
 179#define HEX_GROUP_SIZE		1
 180/* include ASCII after the hex output */
 181#define HEX_ASCII		1
 182/* max number of lines to be printed */
 183#define HEX_MAX_LINES		2
 184
 185/* the list of all allocated objects */
 186static LIST_HEAD(object_list);
 187/* the list of gray-colored objects (see color_gray comment below) */
 188static LIST_HEAD(gray_list);
 189/* memory pool allocation */
 190static struct kmemleak_object mem_pool[CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE];
 191static int mem_pool_free_count = ARRAY_SIZE(mem_pool);
 192static LIST_HEAD(mem_pool_free_list);
 193/* search tree for object boundaries */
 194static struct rb_root object_tree_root = RB_ROOT;
 195/* protecting the access to object_list and object_tree_root */
 196static DEFINE_RAW_SPINLOCK(kmemleak_lock);
 197
 198/* allocation caches for kmemleak internal data */
 199static struct kmem_cache *object_cache;
 200static struct kmem_cache *scan_area_cache;
 201
 202/* set if tracing memory operations is enabled */
 203static int kmemleak_enabled = 1;
 204/* same as above but only for the kmemleak_free() callback */
 205static int kmemleak_free_enabled = 1;
 206/* set in the late_initcall if there were no errors */
 207static int kmemleak_initialized;
 
 
 208/* set if a kmemleak warning was issued */
 209static int kmemleak_warning;
 210/* set if a fatal kmemleak error has occurred */
 211static int kmemleak_error;
 212
 213/* minimum and maximum address that may be valid pointers */
 214static unsigned long min_addr = ULONG_MAX;
 215static unsigned long max_addr;
 216
 217static struct task_struct *scan_thread;
 218/* used to avoid reporting of recently allocated objects */
 219static unsigned long jiffies_min_age;
 220static unsigned long jiffies_last_scan;
 221/* delay between automatic memory scannings */
 222static unsigned long jiffies_scan_wait;
 223/* enables or disables the task stacks scanning */
 224static int kmemleak_stack_scan = 1;
 225/* protects the memory scanning, parameters and debug/kmemleak file access */
 226static DEFINE_MUTEX(scan_mutex);
 227/* setting kmemleak=on, will set this var, skipping the disable */
 228static int kmemleak_skip_disable;
 229/* If there are leaks that can be reported */
 230static bool kmemleak_found_leaks;
 231
 232static bool kmemleak_verbose;
 233module_param_named(verbose, kmemleak_verbose, bool, 0600);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 234
 235static void kmemleak_disable(void);
 236
 237/*
 238 * Print a warning and dump the stack trace.
 239 */
 240#define kmemleak_warn(x...)	do {		\
 241	pr_warn(x);				\
 242	dump_stack();				\
 243	kmemleak_warning = 1;			\
 244} while (0)
 245
 246/*
 247 * Macro invoked when a serious kmemleak condition occurred and cannot be
 248 * recovered from. Kmemleak will be disabled and further allocation/freeing
 249 * tracing no longer available.
 250 */
 251#define kmemleak_stop(x...)	do {	\
 252	kmemleak_warn(x);		\
 253	kmemleak_disable();		\
 254} while (0)
 255
 256#define warn_or_seq_printf(seq, fmt, ...)	do {	\
 257	if (seq)					\
 258		seq_printf(seq, fmt, ##__VA_ARGS__);	\
 259	else						\
 260		pr_warn(fmt, ##__VA_ARGS__);		\
 261} while (0)
 262
 263static void warn_or_seq_hex_dump(struct seq_file *seq, int prefix_type,
 264				 int rowsize, int groupsize, const void *buf,
 265				 size_t len, bool ascii)
 266{
 267	if (seq)
 268		seq_hex_dump(seq, HEX_PREFIX, prefix_type, rowsize, groupsize,
 269			     buf, len, ascii);
 270	else
 271		print_hex_dump(KERN_WARNING, pr_fmt(HEX_PREFIX), prefix_type,
 272			       rowsize, groupsize, buf, len, ascii);
 273}
 274
 275/*
 276 * Printing of the objects hex dump to the seq file. The number of lines to be
 277 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
 278 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
 279 * with the object->lock held.
 280 */
 281static void hex_dump_object(struct seq_file *seq,
 282			    struct kmemleak_object *object)
 283{
 284	const u8 *ptr = (const u8 *)object->pointer;
 285	size_t len;
 
 286
 287	/* limit the number of lines to HEX_MAX_LINES */
 288	len = min_t(size_t, object->size, HEX_MAX_LINES * HEX_ROW_SIZE);
 
 289
 290	warn_or_seq_printf(seq, "  hex dump (first %zu bytes):\n", len);
 291	kasan_disable_current();
 292	warn_or_seq_hex_dump(seq, DUMP_PREFIX_NONE, HEX_ROW_SIZE,
 293			     HEX_GROUP_SIZE, kasan_reset_tag((void *)ptr), len, HEX_ASCII);
 294	kasan_enable_current();
 
 
 
 
 
 295}
 296
 297/*
 298 * Object colors, encoded with count and min_count:
 299 * - white - orphan object, not enough references to it (count < min_count)
 300 * - gray  - not orphan, not marked as false positive (min_count == 0) or
 301 *		sufficient references to it (count >= min_count)
 302 * - black - ignore, it doesn't contain references (e.g. text section)
 303 *		(min_count == -1). No function defined for this color.
 304 * Newly created objects don't have any color assigned (object->count == -1)
 305 * before the next memory scan when they become white.
 306 */
 307static bool color_white(const struct kmemleak_object *object)
 308{
 309	return object->count != KMEMLEAK_BLACK &&
 310		object->count < object->min_count;
 311}
 312
 313static bool color_gray(const struct kmemleak_object *object)
 314{
 315	return object->min_count != KMEMLEAK_BLACK &&
 316		object->count >= object->min_count;
 317}
 318
 319/*
 320 * Objects are considered unreferenced only if their color is white, they have
 321 * not be deleted and have a minimum age to avoid false positives caused by
 322 * pointers temporarily stored in CPU registers.
 323 */
 324static bool unreferenced_object(struct kmemleak_object *object)
 325{
 326	return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
 327		time_before_eq(object->jiffies + jiffies_min_age,
 328			       jiffies_last_scan);
 329}
 330
 331/*
 332 * Printing of the unreferenced objects information to the seq file. The
 333 * print_unreferenced function must be called with the object->lock held.
 334 */
 335static void print_unreferenced(struct seq_file *seq,
 336			       struct kmemleak_object *object)
 337{
 338	int i;
 339	unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
 340
 341	warn_or_seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
 342		   object->pointer, object->size);
 343	warn_or_seq_printf(seq, "  comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
 344		   object->comm, object->pid, object->jiffies,
 345		   msecs_age / 1000, msecs_age % 1000);
 346	hex_dump_object(seq, object);
 347	warn_or_seq_printf(seq, "  backtrace:\n");
 348
 349	for (i = 0; i < object->trace_len; i++) {
 350		void *ptr = (void *)object->trace[i];
 351		warn_or_seq_printf(seq, "    [<%p>] %pS\n", ptr, ptr);
 352	}
 353}
 354
 355/*
 356 * Print the kmemleak_object information. This function is used mainly for
 357 * debugging special cases when kmemleak operations. It must be called with
 358 * the object->lock held.
 359 */
 360static void dump_object_info(struct kmemleak_object *object)
 361{
 
 
 
 
 
 362	pr_notice("Object 0x%08lx (size %zu):\n",
 363		  object->pointer, object->size);
 364	pr_notice("  comm \"%s\", pid %d, jiffies %lu\n",
 365		  object->comm, object->pid, object->jiffies);
 366	pr_notice("  min_count = %d\n", object->min_count);
 367	pr_notice("  count = %d\n", object->count);
 368	pr_notice("  flags = 0x%x\n", object->flags);
 369	pr_notice("  checksum = %u\n", object->checksum);
 370	pr_notice("  backtrace:\n");
 371	stack_trace_print(object->trace, object->trace_len, 4);
 372}
 373
 374/*
 375 * Look-up a memory block metadata (kmemleak_object) in the object search
 376 * tree based on a pointer value. If alias is 0, only values pointing to the
 377 * beginning of the memory block are allowed. The kmemleak_lock must be held
 378 * when calling this function.
 379 */
 380static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
 381{
 382	struct rb_node *rb = object_tree_root.rb_node;
 383
 384	while (rb) {
 385		struct kmemleak_object *object =
 386			rb_entry(rb, struct kmemleak_object, rb_node);
 387		if (ptr < object->pointer)
 388			rb = object->rb_node.rb_left;
 389		else if (object->pointer + object->size <= ptr)
 390			rb = object->rb_node.rb_right;
 391		else if (object->pointer == ptr || alias)
 392			return object;
 393		else {
 394			kmemleak_warn("Found object by alias at 0x%08lx\n",
 395				      ptr);
 396			dump_object_info(object);
 397			break;
 398		}
 399	}
 400	return NULL;
 401}
 402
 403/*
 404 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
 405 * that once an object's use_count reached 0, the RCU freeing was already
 406 * registered and the object should no longer be used. This function must be
 407 * called under the protection of rcu_read_lock().
 408 */
 409static int get_object(struct kmemleak_object *object)
 410{
 411	return atomic_inc_not_zero(&object->use_count);
 412}
 413
 414/*
 415 * Memory pool allocation and freeing. kmemleak_lock must not be held.
 416 */
 417static struct kmemleak_object *mem_pool_alloc(gfp_t gfp)
 418{
 419	unsigned long flags;
 420	struct kmemleak_object *object;
 421
 422	/* try the slab allocator first */
 423	if (object_cache) {
 424		object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
 425		if (object)
 426			return object;
 427	}
 428
 429	/* slab allocation failed, try the memory pool */
 430	raw_spin_lock_irqsave(&kmemleak_lock, flags);
 431	object = list_first_entry_or_null(&mem_pool_free_list,
 432					  typeof(*object), object_list);
 433	if (object)
 434		list_del(&object->object_list);
 435	else if (mem_pool_free_count)
 436		object = &mem_pool[--mem_pool_free_count];
 437	else
 438		pr_warn_once("Memory pool empty, consider increasing CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE\n");
 439	raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
 440
 441	return object;
 442}
 443
 444/*
 445 * Return the object to either the slab allocator or the memory pool.
 446 */
 447static void mem_pool_free(struct kmemleak_object *object)
 448{
 449	unsigned long flags;
 450
 451	if (object < mem_pool || object >= mem_pool + ARRAY_SIZE(mem_pool)) {
 452		kmem_cache_free(object_cache, object);
 453		return;
 454	}
 455
 456	/* add the object to the memory pool free list */
 457	raw_spin_lock_irqsave(&kmemleak_lock, flags);
 458	list_add(&object->object_list, &mem_pool_free_list);
 459	raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
 460}
 461
 462/*
 463 * RCU callback to free a kmemleak_object.
 464 */
 465static void free_object_rcu(struct rcu_head *rcu)
 466{
 467	struct hlist_node *tmp;
 468	struct kmemleak_scan_area *area;
 469	struct kmemleak_object *object =
 470		container_of(rcu, struct kmemleak_object, rcu);
 471
 472	/*
 473	 * Once use_count is 0 (guaranteed by put_object), there is no other
 474	 * code accessing this object, hence no need for locking.
 475	 */
 476	hlist_for_each_entry_safe(area, tmp, &object->area_list, node) {
 477		hlist_del(&area->node);
 478		kmem_cache_free(scan_area_cache, area);
 479	}
 480	mem_pool_free(object);
 481}
 482
 483/*
 484 * Decrement the object use_count. Once the count is 0, free the object using
 485 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
 486 * delete_object() path, the delayed RCU freeing ensures that there is no
 487 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
 488 * is also possible.
 489 */
 490static void put_object(struct kmemleak_object *object)
 491{
 492	if (!atomic_dec_and_test(&object->use_count))
 493		return;
 494
 495	/* should only get here after delete_object was called */
 496	WARN_ON(object->flags & OBJECT_ALLOCATED);
 497
 498	/*
 499	 * It may be too early for the RCU callbacks, however, there is no
 500	 * concurrent object_list traversal when !object_cache and all objects
 501	 * came from the memory pool. Free the object directly.
 502	 */
 503	if (object_cache)
 504		call_rcu(&object->rcu, free_object_rcu);
 505	else
 506		free_object_rcu(&object->rcu);
 507}
 508
 509/*
 510 * Look up an object in the object search tree and increase its use_count.
 511 */
 512static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
 513{
 514	unsigned long flags;
 515	struct kmemleak_object *object;
 516
 517	rcu_read_lock();
 518	raw_spin_lock_irqsave(&kmemleak_lock, flags);
 519	object = lookup_object(ptr, alias);
 520	raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
 
 521
 522	/* check whether the object is still available */
 523	if (object && !get_object(object))
 524		object = NULL;
 525	rcu_read_unlock();
 526
 527	return object;
 528}
 529
 530/*
 531 * Remove an object from the object_tree_root and object_list. Must be called
 532 * with the kmemleak_lock held _if_ kmemleak is still enabled.
 533 */
 534static void __remove_object(struct kmemleak_object *object)
 535{
 536	rb_erase(&object->rb_node, &object_tree_root);
 537	list_del_rcu(&object->object_list);
 538}
 539
 540/*
 541 * Look up an object in the object search tree and remove it from both
 542 * object_tree_root and object_list. The returned object's use_count should be
 543 * at least 1, as initially set by create_object().
 544 */
 545static struct kmemleak_object *find_and_remove_object(unsigned long ptr, int alias)
 546{
 547	unsigned long flags;
 548	struct kmemleak_object *object;
 549
 550	raw_spin_lock_irqsave(&kmemleak_lock, flags);
 551	object = lookup_object(ptr, alias);
 552	if (object)
 553		__remove_object(object);
 554	raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
 555
 556	return object;
 557}
 558
 559/*
 560 * Save stack trace to the given array of MAX_TRACE size.
 561 */
 562static int __save_stack_trace(unsigned long *trace)
 563{
 564	return stack_trace_save(trace, MAX_TRACE, 2);
 
 
 
 
 
 
 
 
 565}
 566
 567/*
 568 * Create the metadata (struct kmemleak_object) corresponding to an allocated
 569 * memory block and add it to the object_list and object_tree_root.
 570 */
 571static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
 572					     int min_count, gfp_t gfp)
 573{
 574	unsigned long flags;
 575	struct kmemleak_object *object, *parent;
 576	struct rb_node **link, *rb_parent;
 577	unsigned long untagged_ptr;
 578
 579	object = mem_pool_alloc(gfp);
 580	if (!object) {
 581		pr_warn("Cannot allocate a kmemleak_object structure\n");
 582		kmemleak_disable();
 583		return NULL;
 584	}
 585
 586	INIT_LIST_HEAD(&object->object_list);
 587	INIT_LIST_HEAD(&object->gray_list);
 588	INIT_HLIST_HEAD(&object->area_list);
 589	raw_spin_lock_init(&object->lock);
 590	atomic_set(&object->use_count, 1);
 591	object->flags = OBJECT_ALLOCATED;
 592	object->pointer = ptr;
 593	object->size = kfence_ksize((void *)ptr) ?: size;
 594	object->excess_ref = 0;
 595	object->min_count = min_count;
 596	object->count = 0;			/* white color initially */
 597	object->jiffies = jiffies;
 598	object->checksum = 0;
 599
 600	/* task information */
 601	if (in_irq()) {
 602		object->pid = 0;
 603		strncpy(object->comm, "hardirq", sizeof(object->comm));
 604	} else if (in_serving_softirq()) {
 605		object->pid = 0;
 606		strncpy(object->comm, "softirq", sizeof(object->comm));
 607	} else {
 608		object->pid = current->pid;
 609		/*
 610		 * There is a small chance of a race with set_task_comm(),
 611		 * however using get_task_comm() here may cause locking
 612		 * dependency issues with current->alloc_lock. In the worst
 613		 * case, the command line is not correct.
 614		 */
 615		strncpy(object->comm, current->comm, sizeof(object->comm));
 616	}
 617
 618	/* kernel backtrace */
 619	object->trace_len = __save_stack_trace(object->trace);
 620
 621	raw_spin_lock_irqsave(&kmemleak_lock, flags);
 622
 623	untagged_ptr = (unsigned long)kasan_reset_tag((void *)ptr);
 624	min_addr = min(min_addr, untagged_ptr);
 625	max_addr = max(max_addr, untagged_ptr + size);
 626	link = &object_tree_root.rb_node;
 627	rb_parent = NULL;
 628	while (*link) {
 629		rb_parent = *link;
 630		parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
 631		if (ptr + size <= parent->pointer)
 632			link = &parent->rb_node.rb_left;
 633		else if (parent->pointer + parent->size <= ptr)
 634			link = &parent->rb_node.rb_right;
 635		else {
 636			kmemleak_stop("Cannot insert 0x%lx into the object search tree (overlaps existing)\n",
 
 637				      ptr);
 638			/*
 639			 * No need for parent->lock here since "parent" cannot
 640			 * be freed while the kmemleak_lock is held.
 641			 */
 642			dump_object_info(parent);
 643			kmem_cache_free(object_cache, object);
 644			object = NULL;
 
 
 
 645			goto out;
 646		}
 647	}
 648	rb_link_node(&object->rb_node, rb_parent, link);
 649	rb_insert_color(&object->rb_node, &object_tree_root);
 650
 651	list_add_tail_rcu(&object->object_list, &object_list);
 652out:
 653	raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
 654	return object;
 655}
 656
 657/*
 658 * Mark the object as not allocated and schedule RCU freeing via put_object().
 
 659 */
 660static void __delete_object(struct kmemleak_object *object)
 661{
 662	unsigned long flags;
 663
 
 
 
 
 
 664	WARN_ON(!(object->flags & OBJECT_ALLOCATED));
 665	WARN_ON(atomic_read(&object->use_count) < 1);
 666
 667	/*
 668	 * Locking here also ensures that the corresponding memory block
 669	 * cannot be freed when it is being scanned.
 670	 */
 671	raw_spin_lock_irqsave(&object->lock, flags);
 672	object->flags &= ~OBJECT_ALLOCATED;
 673	raw_spin_unlock_irqrestore(&object->lock, flags);
 674	put_object(object);
 675}
 676
 677/*
 678 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
 679 * delete it.
 680 */
 681static void delete_object_full(unsigned long ptr)
 682{
 683	struct kmemleak_object *object;
 684
 685	object = find_and_remove_object(ptr, 0);
 686	if (!object) {
 687#ifdef DEBUG
 688		kmemleak_warn("Freeing unknown object at 0x%08lx\n",
 689			      ptr);
 690#endif
 691		return;
 692	}
 693	__delete_object(object);
 
 694}
 695
 696/*
 697 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
 698 * delete it. If the memory block is partially freed, the function may create
 699 * additional metadata for the remaining parts of the block.
 700 */
 701static void delete_object_part(unsigned long ptr, size_t size)
 702{
 703	struct kmemleak_object *object;
 704	unsigned long start, end;
 705
 706	object = find_and_remove_object(ptr, 1);
 707	if (!object) {
 708#ifdef DEBUG
 709		kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n",
 710			      ptr, size);
 711#endif
 712		return;
 713	}
 
 714
 715	/*
 716	 * Create one or two objects that may result from the memory block
 717	 * split. Note that partial freeing is only done by free_bootmem() and
 718	 * this happens before kmemleak_init() is called.
 
 
 719	 */
 720	start = object->pointer;
 721	end = object->pointer + object->size;
 722	if (ptr > start)
 723		create_object(start, ptr - start, object->min_count,
 724			      GFP_KERNEL);
 725	if (ptr + size < end)
 726		create_object(ptr + size, end - ptr - size, object->min_count,
 727			      GFP_KERNEL);
 728
 729	__delete_object(object);
 730}
 731
 732static void __paint_it(struct kmemleak_object *object, int color)
 733{
 734	object->min_count = color;
 735	if (color == KMEMLEAK_BLACK)
 736		object->flags |= OBJECT_NO_SCAN;
 737}
 738
 739static void paint_it(struct kmemleak_object *object, int color)
 740{
 741	unsigned long flags;
 742
 743	raw_spin_lock_irqsave(&object->lock, flags);
 744	__paint_it(object, color);
 745	raw_spin_unlock_irqrestore(&object->lock, flags);
 746}
 747
 748static void paint_ptr(unsigned long ptr, int color)
 749{
 750	struct kmemleak_object *object;
 751
 752	object = find_and_get_object(ptr, 0);
 753	if (!object) {
 754		kmemleak_warn("Trying to color unknown object at 0x%08lx as %s\n",
 755			      ptr,
 756			      (color == KMEMLEAK_GREY) ? "Grey" :
 757			      (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
 758		return;
 759	}
 760	paint_it(object, color);
 761	put_object(object);
 762}
 763
 764/*
 765 * Mark an object permanently as gray-colored so that it can no longer be
 766 * reported as a leak. This is used in general to mark a false positive.
 767 */
 768static void make_gray_object(unsigned long ptr)
 769{
 770	paint_ptr(ptr, KMEMLEAK_GREY);
 771}
 772
 773/*
 774 * Mark the object as black-colored so that it is ignored from scans and
 775 * reporting.
 776 */
 777static void make_black_object(unsigned long ptr)
 778{
 779	paint_ptr(ptr, KMEMLEAK_BLACK);
 780}
 781
 782/*
 783 * Add a scanning area to the object. If at least one such area is added,
 784 * kmemleak will only scan these ranges rather than the whole memory block.
 785 */
 786static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
 787{
 788	unsigned long flags;
 789	struct kmemleak_object *object;
 790	struct kmemleak_scan_area *area = NULL;
 791
 792	object = find_and_get_object(ptr, 1);
 793	if (!object) {
 794		kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
 795			      ptr);
 796		return;
 797	}
 798
 799	if (scan_area_cache)
 800		area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
 801
 802	raw_spin_lock_irqsave(&object->lock, flags);
 803	if (!area) {
 804		pr_warn_once("Cannot allocate a scan area, scanning the full object\n");
 805		/* mark the object for full scan to avoid false positives */
 806		object->flags |= OBJECT_FULL_SCAN;
 807		goto out_unlock;
 808	}
 
 
 809	if (size == SIZE_MAX) {
 810		size = object->pointer + object->size - ptr;
 811	} else if (ptr + size > object->pointer + object->size) {
 812		kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
 813		dump_object_info(object);
 814		kmem_cache_free(scan_area_cache, area);
 815		goto out_unlock;
 816	}
 817
 818	INIT_HLIST_NODE(&area->node);
 819	area->start = ptr;
 820	area->size = size;
 821
 822	hlist_add_head(&area->node, &object->area_list);
 823out_unlock:
 824	raw_spin_unlock_irqrestore(&object->lock, flags);
 
 825	put_object(object);
 826}
 827
 828/*
 829 * Any surplus references (object already gray) to 'ptr' are passed to
 830 * 'excess_ref'. This is used in the vmalloc() case where a pointer to
 831 * vm_struct may be used as an alternative reference to the vmalloc'ed object
 832 * (see free_thread_stack()).
 833 */
 834static void object_set_excess_ref(unsigned long ptr, unsigned long excess_ref)
 835{
 836	unsigned long flags;
 837	struct kmemleak_object *object;
 838
 839	object = find_and_get_object(ptr, 0);
 840	if (!object) {
 841		kmemleak_warn("Setting excess_ref on unknown object at 0x%08lx\n",
 842			      ptr);
 843		return;
 844	}
 845
 846	raw_spin_lock_irqsave(&object->lock, flags);
 847	object->excess_ref = excess_ref;
 848	raw_spin_unlock_irqrestore(&object->lock, flags);
 849	put_object(object);
 850}
 851
 852/*
 853 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
 854 * pointer. Such object will not be scanned by kmemleak but references to it
 855 * are searched.
 856 */
 857static void object_no_scan(unsigned long ptr)
 
 858{
 859	unsigned long flags;
 860	struct kmemleak_object *object;
 861
 862	object = find_and_get_object(ptr, 0);
 863	if (!object) {
 864		kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
 865		return;
 866	}
 867
 868	raw_spin_lock_irqsave(&object->lock, flags);
 869	object->flags |= OBJECT_NO_SCAN;
 870	raw_spin_unlock_irqrestore(&object->lock, flags);
 871	put_object(object);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 872}
 873
 874/**
 875 * kmemleak_alloc - register a newly allocated object
 876 * @ptr:	pointer to beginning of the object
 877 * @size:	size of the object
 878 * @min_count:	minimum number of references to this object. If during memory
 879 *		scanning a number of references less than @min_count is found,
 880 *		the object is reported as a memory leak. If @min_count is 0,
 881 *		the object is never reported as a leak. If @min_count is -1,
 882 *		the object is ignored (not scanned and not reported as a leak)
 883 * @gfp:	kmalloc() flags used for kmemleak internal memory allocations
 884 *
 885 * This function is called from the kernel allocators when a new object
 886 * (memory block) is allocated (kmem_cache_alloc, kmalloc etc.).
 887 */
 888void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
 889			  gfp_t gfp)
 890{
 891	pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
 892
 893	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
 894		create_object((unsigned long)ptr, size, min_count, gfp);
 
 
 895}
 896EXPORT_SYMBOL_GPL(kmemleak_alloc);
 897
 898/**
 899 * kmemleak_alloc_percpu - register a newly allocated __percpu object
 900 * @ptr:	__percpu pointer to beginning of the object
 901 * @size:	size of the object
 902 * @gfp:	flags used for kmemleak internal memory allocations
 903 *
 904 * This function is called from the kernel percpu allocator when a new object
 905 * (memory block) is allocated (alloc_percpu).
 
 906 */
 907void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size,
 908				 gfp_t gfp)
 909{
 910	unsigned int cpu;
 911
 912	pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
 913
 914	/*
 915	 * Percpu allocations are only scanned and not reported as leaks
 916	 * (min_count is set to 0).
 917	 */
 918	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
 919		for_each_possible_cpu(cpu)
 920			create_object((unsigned long)per_cpu_ptr(ptr, cpu),
 921				      size, 0, gfp);
 
 
 922}
 923EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
 924
 925/**
 926 * kmemleak_vmalloc - register a newly vmalloc'ed object
 927 * @area:	pointer to vm_struct
 928 * @size:	size of the object
 929 * @gfp:	__vmalloc() flags used for kmemleak internal memory allocations
 930 *
 931 * This function is called from the vmalloc() kernel allocator when a new
 932 * object (memory block) is allocated.
 933 */
 934void __ref kmemleak_vmalloc(const struct vm_struct *area, size_t size, gfp_t gfp)
 935{
 936	pr_debug("%s(0x%p, %zu)\n", __func__, area, size);
 937
 938	/*
 939	 * A min_count = 2 is needed because vm_struct contains a reference to
 940	 * the virtual address of the vmalloc'ed block.
 941	 */
 942	if (kmemleak_enabled) {
 943		create_object((unsigned long)area->addr, size, 2, gfp);
 944		object_set_excess_ref((unsigned long)area,
 945				      (unsigned long)area->addr);
 946	}
 947}
 948EXPORT_SYMBOL_GPL(kmemleak_vmalloc);
 949
 950/**
 951 * kmemleak_free - unregister a previously registered object
 952 * @ptr:	pointer to beginning of the object
 953 *
 954 * This function is called from the kernel allocators when an object (memory
 955 * block) is freed (kmem_cache_free, kfree, vfree etc.).
 956 */
 957void __ref kmemleak_free(const void *ptr)
 958{
 959	pr_debug("%s(0x%p)\n", __func__, ptr);
 960
 961	if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
 962		delete_object_full((unsigned long)ptr);
 
 
 963}
 964EXPORT_SYMBOL_GPL(kmemleak_free);
 965
 966/**
 967 * kmemleak_free_part - partially unregister a previously registered object
 968 * @ptr:	pointer to the beginning or inside the object. This also
 969 *		represents the start of the range to be freed
 970 * @size:	size to be unregistered
 971 *
 972 * This function is called when only a part of a memory block is freed
 973 * (usually from the bootmem allocator).
 974 */
 975void __ref kmemleak_free_part(const void *ptr, size_t size)
 976{
 977	pr_debug("%s(0x%p)\n", __func__, ptr);
 978
 979	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
 980		delete_object_part((unsigned long)ptr, size);
 
 
 981}
 982EXPORT_SYMBOL_GPL(kmemleak_free_part);
 983
 984/**
 985 * kmemleak_free_percpu - unregister a previously registered __percpu object
 986 * @ptr:	__percpu pointer to beginning of the object
 987 *
 988 * This function is called from the kernel percpu allocator when an object
 989 * (memory block) is freed (free_percpu).
 990 */
 991void __ref kmemleak_free_percpu(const void __percpu *ptr)
 992{
 993	unsigned int cpu;
 994
 995	pr_debug("%s(0x%p)\n", __func__, ptr);
 996
 997	if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
 998		for_each_possible_cpu(cpu)
 999			delete_object_full((unsigned long)per_cpu_ptr(ptr,
1000								      cpu));
 
 
1001}
1002EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
1003
1004/**
1005 * kmemleak_update_trace - update object allocation stack trace
1006 * @ptr:	pointer to beginning of the object
1007 *
1008 * Override the object allocation stack trace for cases where the actual
1009 * allocation place is not always useful.
1010 */
1011void __ref kmemleak_update_trace(const void *ptr)
1012{
1013	struct kmemleak_object *object;
1014	unsigned long flags;
1015
1016	pr_debug("%s(0x%p)\n", __func__, ptr);
1017
1018	if (!kmemleak_enabled || IS_ERR_OR_NULL(ptr))
1019		return;
1020
1021	object = find_and_get_object((unsigned long)ptr, 1);
1022	if (!object) {
1023#ifdef DEBUG
1024		kmemleak_warn("Updating stack trace for unknown object at %p\n",
1025			      ptr);
1026#endif
1027		return;
1028	}
1029
1030	raw_spin_lock_irqsave(&object->lock, flags);
1031	object->trace_len = __save_stack_trace(object->trace);
1032	raw_spin_unlock_irqrestore(&object->lock, flags);
1033
1034	put_object(object);
1035}
1036EXPORT_SYMBOL(kmemleak_update_trace);
1037
1038/**
1039 * kmemleak_not_leak - mark an allocated object as false positive
1040 * @ptr:	pointer to beginning of the object
1041 *
1042 * Calling this function on an object will cause the memory block to no longer
1043 * be reported as leak and always be scanned.
1044 */
1045void __ref kmemleak_not_leak(const void *ptr)
1046{
1047	pr_debug("%s(0x%p)\n", __func__, ptr);
1048
1049	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1050		make_gray_object((unsigned long)ptr);
 
 
1051}
1052EXPORT_SYMBOL(kmemleak_not_leak);
1053
1054/**
1055 * kmemleak_ignore - ignore an allocated object
1056 * @ptr:	pointer to beginning of the object
1057 *
1058 * Calling this function on an object will cause the memory block to be
1059 * ignored (not scanned and not reported as a leak). This is usually done when
1060 * it is known that the corresponding block is not a leak and does not contain
1061 * any references to other allocated memory blocks.
1062 */
1063void __ref kmemleak_ignore(const void *ptr)
1064{
1065	pr_debug("%s(0x%p)\n", __func__, ptr);
1066
1067	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1068		make_black_object((unsigned long)ptr);
 
 
1069}
1070EXPORT_SYMBOL(kmemleak_ignore);
1071
1072/**
1073 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1074 * @ptr:	pointer to beginning or inside the object. This also
1075 *		represents the start of the scan area
1076 * @size:	size of the scan area
1077 * @gfp:	kmalloc() flags used for kmemleak internal memory allocations
1078 *
1079 * This function is used when it is known that only certain parts of an object
1080 * contain references to other objects. Kmemleak will only scan these areas
1081 * reducing the number false negatives.
1082 */
1083void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
1084{
1085	pr_debug("%s(0x%p)\n", __func__, ptr);
1086
1087	if (kmemleak_enabled && ptr && size && !IS_ERR(ptr))
1088		add_scan_area((unsigned long)ptr, size, gfp);
 
 
1089}
1090EXPORT_SYMBOL(kmemleak_scan_area);
1091
1092/**
1093 * kmemleak_no_scan - do not scan an allocated object
1094 * @ptr:	pointer to beginning of the object
1095 *
1096 * This function notifies kmemleak not to scan the given memory block. Useful
1097 * in situations where it is known that the given object does not contain any
1098 * references to other objects. Kmemleak will not scan such objects reducing
1099 * the number of false negatives.
1100 */
1101void __ref kmemleak_no_scan(const void *ptr)
1102{
1103	pr_debug("%s(0x%p)\n", __func__, ptr);
1104
1105	if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1106		object_no_scan((unsigned long)ptr);
 
 
1107}
1108EXPORT_SYMBOL(kmemleak_no_scan);
1109
1110/**
1111 * kmemleak_alloc_phys - similar to kmemleak_alloc but taking a physical
1112 *			 address argument
1113 * @phys:	physical address of the object
1114 * @size:	size of the object
1115 * @min_count:	minimum number of references to this object.
1116 *              See kmemleak_alloc()
1117 * @gfp:	kmalloc() flags used for kmemleak internal memory allocations
1118 */
1119void __ref kmemleak_alloc_phys(phys_addr_t phys, size_t size, int min_count,
1120			       gfp_t gfp)
1121{
1122	if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1123		kmemleak_alloc(__va(phys), size, min_count, gfp);
1124}
1125EXPORT_SYMBOL(kmemleak_alloc_phys);
1126
1127/**
1128 * kmemleak_free_part_phys - similar to kmemleak_free_part but taking a
1129 *			     physical address argument
1130 * @phys:	physical address if the beginning or inside an object. This
1131 *		also represents the start of the range to be freed
1132 * @size:	size to be unregistered
1133 */
1134void __ref kmemleak_free_part_phys(phys_addr_t phys, size_t size)
1135{
1136	if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1137		kmemleak_free_part(__va(phys), size);
1138}
1139EXPORT_SYMBOL(kmemleak_free_part_phys);
1140
1141/**
1142 * kmemleak_not_leak_phys - similar to kmemleak_not_leak but taking a physical
1143 *			    address argument
1144 * @phys:	physical address of the object
1145 */
1146void __ref kmemleak_not_leak_phys(phys_addr_t phys)
1147{
1148	if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1149		kmemleak_not_leak(__va(phys));
1150}
1151EXPORT_SYMBOL(kmemleak_not_leak_phys);
1152
1153/**
1154 * kmemleak_ignore_phys - similar to kmemleak_ignore but taking a physical
1155 *			  address argument
1156 * @phys:	physical address of the object
1157 */
1158void __ref kmemleak_ignore_phys(phys_addr_t phys)
1159{
1160	if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1161		kmemleak_ignore(__va(phys));
1162}
1163EXPORT_SYMBOL(kmemleak_ignore_phys);
1164
1165/*
1166 * Update an object's checksum and return true if it was modified.
1167 */
1168static bool update_checksum(struct kmemleak_object *object)
1169{
1170	u32 old_csum = object->checksum;
1171
1172	kasan_disable_current();
1173	kcsan_disable_current();
1174	object->checksum = crc32(0, kasan_reset_tag((void *)object->pointer), object->size);
1175	kasan_enable_current();
1176	kcsan_enable_current();
1177
 
1178	return object->checksum != old_csum;
1179}
1180
1181/*
1182 * Update an object's references. object->lock must be held by the caller.
1183 */
1184static void update_refs(struct kmemleak_object *object)
1185{
1186	if (!color_white(object)) {
1187		/* non-orphan, ignored or new */
1188		return;
1189	}
1190
1191	/*
1192	 * Increase the object's reference count (number of pointers to the
1193	 * memory block). If this count reaches the required minimum, the
1194	 * object's color will become gray and it will be added to the
1195	 * gray_list.
1196	 */
1197	object->count++;
1198	if (color_gray(object)) {
1199		/* put_object() called when removing from gray_list */
1200		WARN_ON(!get_object(object));
1201		list_add_tail(&object->gray_list, &gray_list);
1202	}
1203}
1204
1205/*
1206 * Memory scanning is a long process and it needs to be interruptible. This
1207 * function checks whether such interrupt condition occurred.
1208 */
1209static int scan_should_stop(void)
1210{
1211	if (!kmemleak_enabled)
1212		return 1;
1213
1214	/*
1215	 * This function may be called from either process or kthread context,
1216	 * hence the need to check for both stop conditions.
1217	 */
1218	if (current->mm)
1219		return signal_pending(current);
1220	else
1221		return kthread_should_stop();
1222
1223	return 0;
1224}
1225
1226/*
1227 * Scan a memory block (exclusive range) for valid pointers and add those
1228 * found to the gray list.
1229 */
1230static void scan_block(void *_start, void *_end,
1231		       struct kmemleak_object *scanned)
1232{
1233	unsigned long *ptr;
1234	unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1235	unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1236	unsigned long flags;
1237	unsigned long untagged_ptr;
1238
1239	raw_spin_lock_irqsave(&kmemleak_lock, flags);
1240	for (ptr = start; ptr < end; ptr++) {
1241		struct kmemleak_object *object;
 
1242		unsigned long pointer;
1243		unsigned long excess_ref;
1244
 
 
1245		if (scan_should_stop())
1246			break;
1247
1248		kasan_disable_current();
1249		pointer = *(unsigned long *)kasan_reset_tag((void *)ptr);
1250		kasan_enable_current();
1251
1252		untagged_ptr = (unsigned long)kasan_reset_tag((void *)pointer);
1253		if (untagged_ptr < min_addr || untagged_ptr >= max_addr)
1254			continue;
1255
1256		/*
1257		 * No need for get_object() here since we hold kmemleak_lock.
1258		 * object->use_count cannot be dropped to 0 while the object
1259		 * is still present in object_tree_root and object_list
1260		 * (with updates protected by kmemleak_lock).
1261		 */
1262		object = lookup_object(pointer, 1);
1263		if (!object)
1264			continue;
1265		if (object == scanned)
1266			/* self referenced, ignore */
 
1267			continue;
 
1268
1269		/*
1270		 * Avoid the lockdep recursive warning on object->lock being
1271		 * previously acquired in scan_object(). These locks are
1272		 * enclosed by scan_mutex.
1273		 */
1274		raw_spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
1275		/* only pass surplus references (object already gray) */
1276		if (color_gray(object)) {
1277			excess_ref = object->excess_ref;
1278			/* no need for update_refs() if object already gray */
1279		} else {
1280			excess_ref = 0;
1281			update_refs(object);
1282		}
1283		raw_spin_unlock(&object->lock);
1284
1285		if (excess_ref) {
1286			object = lookup_object(excess_ref, 0);
1287			if (!object)
1288				continue;
1289			if (object == scanned)
1290				/* circular reference, ignore */
1291				continue;
1292			raw_spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
1293			update_refs(object);
1294			raw_spin_unlock(&object->lock);
 
1295		}
1296	}
1297	raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
1298}
1299
1300/*
1301 * Scan a large memory block in MAX_SCAN_SIZE chunks to reduce the latency.
1302 */
1303#ifdef CONFIG_SMP
1304static void scan_large_block(void *start, void *end)
1305{
1306	void *next;
1307
1308	while (start < end) {
1309		next = min(start + MAX_SCAN_SIZE, end);
1310		scan_block(start, next, NULL);
1311		start = next;
1312		cond_resched();
1313	}
1314}
1315#endif
1316
1317/*
1318 * Scan a memory block corresponding to a kmemleak_object. A condition is
1319 * that object->use_count >= 1.
1320 */
1321static void scan_object(struct kmemleak_object *object)
1322{
1323	struct kmemleak_scan_area *area;
1324	unsigned long flags;
1325
1326	/*
1327	 * Once the object->lock is acquired, the corresponding memory block
1328	 * cannot be freed (the same lock is acquired in delete_object).
1329	 */
1330	raw_spin_lock_irqsave(&object->lock, flags);
1331	if (object->flags & OBJECT_NO_SCAN)
1332		goto out;
1333	if (!(object->flags & OBJECT_ALLOCATED))
1334		/* already freed object */
1335		goto out;
1336	if (hlist_empty(&object->area_list) ||
1337	    object->flags & OBJECT_FULL_SCAN) {
1338		void *start = (void *)object->pointer;
1339		void *end = (void *)(object->pointer + object->size);
1340		void *next;
1341
1342		do {
1343			next = min(start + MAX_SCAN_SIZE, end);
1344			scan_block(start, next, object);
1345
1346			start = next;
1347			if (start >= end)
1348				break;
 
 
1349
1350			raw_spin_unlock_irqrestore(&object->lock, flags);
1351			cond_resched();
1352			raw_spin_lock_irqsave(&object->lock, flags);
1353		} while (object->flags & OBJECT_ALLOCATED);
1354	} else
1355		hlist_for_each_entry(area, &object->area_list, node)
1356			scan_block((void *)area->start,
1357				   (void *)(area->start + area->size),
1358				   object);
1359out:
1360	raw_spin_unlock_irqrestore(&object->lock, flags);
1361}
1362
1363/*
1364 * Scan the objects already referenced (gray objects). More objects will be
1365 * referenced and, if there are no memory leaks, all the objects are scanned.
1366 */
1367static void scan_gray_list(void)
1368{
1369	struct kmemleak_object *object, *tmp;
1370
1371	/*
1372	 * The list traversal is safe for both tail additions and removals
1373	 * from inside the loop. The kmemleak objects cannot be freed from
1374	 * outside the loop because their use_count was incremented.
1375	 */
1376	object = list_entry(gray_list.next, typeof(*object), gray_list);
1377	while (&object->gray_list != &gray_list) {
1378		cond_resched();
1379
1380		/* may add new objects to the list */
1381		if (!scan_should_stop())
1382			scan_object(object);
1383
1384		tmp = list_entry(object->gray_list.next, typeof(*object),
1385				 gray_list);
1386
1387		/* remove the object from the list and release it */
1388		list_del(&object->gray_list);
1389		put_object(object);
1390
1391		object = tmp;
1392	}
1393	WARN_ON(!list_empty(&gray_list));
1394}
1395
1396/*
1397 * Scan data sections and all the referenced memory blocks allocated via the
1398 * kernel's standard allocators. This function must be called with the
1399 * scan_mutex held.
1400 */
1401static void kmemleak_scan(void)
1402{
1403	unsigned long flags;
1404	struct kmemleak_object *object;
1405	int i;
1406	int new_leaks = 0;
1407
1408	jiffies_last_scan = jiffies;
1409
1410	/* prepare the kmemleak_object's */
1411	rcu_read_lock();
1412	list_for_each_entry_rcu(object, &object_list, object_list) {
1413		raw_spin_lock_irqsave(&object->lock, flags);
1414#ifdef DEBUG
1415		/*
1416		 * With a few exceptions there should be a maximum of
1417		 * 1 reference to any object at this point.
1418		 */
1419		if (atomic_read(&object->use_count) > 1) {
1420			pr_debug("object->use_count = %d\n",
1421				 atomic_read(&object->use_count));
1422			dump_object_info(object);
1423		}
1424#endif
1425		/* reset the reference count (whiten the object) */
1426		object->count = 0;
1427		if (color_gray(object) && get_object(object))
1428			list_add_tail(&object->gray_list, &gray_list);
1429
1430		raw_spin_unlock_irqrestore(&object->lock, flags);
1431	}
1432	rcu_read_unlock();
1433
 
 
 
 
1434#ifdef CONFIG_SMP
1435	/* per-cpu sections scanning */
1436	for_each_possible_cpu(i)
1437		scan_large_block(__per_cpu_start + per_cpu_offset(i),
1438				 __per_cpu_end + per_cpu_offset(i));
1439#endif
1440
1441	/*
1442	 * Struct page scanning for each node.
1443	 */
1444	get_online_mems();
1445	for_each_online_node(i) {
1446		unsigned long start_pfn = node_start_pfn(i);
1447		unsigned long end_pfn = node_end_pfn(i);
1448		unsigned long pfn;
1449
1450		for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1451			struct page *page = pfn_to_online_page(pfn);
1452
1453			if (!page)
1454				continue;
1455
1456			/* only scan pages belonging to this node */
1457			if (page_to_nid(page) != i)
1458				continue;
 
1459			/* only scan if page is in use */
1460			if (page_count(page) == 0)
1461				continue;
1462			scan_block(page, page + 1, NULL);
1463			if (!(pfn & 63))
1464				cond_resched();
1465		}
1466	}
1467	put_online_mems();
1468
1469	/*
1470	 * Scanning the task stacks (may introduce false negatives).
1471	 */
1472	if (kmemleak_stack_scan) {
1473		struct task_struct *p, *g;
1474
1475		rcu_read_lock();
1476		for_each_process_thread(g, p) {
1477			void *stack = try_get_task_stack(p);
1478			if (stack) {
1479				scan_block(stack, stack + THREAD_SIZE, NULL);
1480				put_task_stack(p);
1481			}
1482		}
1483		rcu_read_unlock();
1484	}
1485
1486	/*
1487	 * Scan the objects already referenced from the sections scanned
1488	 * above.
1489	 */
1490	scan_gray_list();
1491
1492	/*
1493	 * Check for new or unreferenced objects modified since the previous
1494	 * scan and color them gray until the next scan.
1495	 */
1496	rcu_read_lock();
1497	list_for_each_entry_rcu(object, &object_list, object_list) {
1498		raw_spin_lock_irqsave(&object->lock, flags);
1499		if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1500		    && update_checksum(object) && get_object(object)) {
1501			/* color it gray temporarily */
1502			object->count = object->min_count;
1503			list_add_tail(&object->gray_list, &gray_list);
1504		}
1505		raw_spin_unlock_irqrestore(&object->lock, flags);
1506	}
1507	rcu_read_unlock();
1508
1509	/*
1510	 * Re-scan the gray list for modified unreferenced objects.
1511	 */
1512	scan_gray_list();
1513
1514	/*
1515	 * If scanning was stopped do not report any new unreferenced objects.
1516	 */
1517	if (scan_should_stop())
1518		return;
1519
1520	/*
1521	 * Scanning result reporting.
1522	 */
1523	rcu_read_lock();
1524	list_for_each_entry_rcu(object, &object_list, object_list) {
1525		raw_spin_lock_irqsave(&object->lock, flags);
1526		if (unreferenced_object(object) &&
1527		    !(object->flags & OBJECT_REPORTED)) {
1528			object->flags |= OBJECT_REPORTED;
1529
1530			if (kmemleak_verbose)
1531				print_unreferenced(NULL, object);
1532
1533			new_leaks++;
1534		}
1535		raw_spin_unlock_irqrestore(&object->lock, flags);
1536	}
1537	rcu_read_unlock();
1538
1539	if (new_leaks) {
1540		kmemleak_found_leaks = true;
1541
1542		pr_info("%d new suspected memory leaks (see /sys/kernel/debug/kmemleak)\n",
1543			new_leaks);
1544	}
1545
1546}
1547
1548/*
1549 * Thread function performing automatic memory scanning. Unreferenced objects
1550 * at the end of a memory scan are reported but only the first time.
1551 */
1552static int kmemleak_scan_thread(void *arg)
1553{
1554	static int first_run = IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN);
1555
1556	pr_info("Automatic memory scanning thread started\n");
1557	set_user_nice(current, 10);
1558
1559	/*
1560	 * Wait before the first scan to allow the system to fully initialize.
1561	 */
1562	if (first_run) {
1563		signed long timeout = msecs_to_jiffies(SECS_FIRST_SCAN * 1000);
1564		first_run = 0;
1565		while (timeout && !kthread_should_stop())
1566			timeout = schedule_timeout_interruptible(timeout);
1567	}
1568
1569	while (!kthread_should_stop()) {
1570		signed long timeout = READ_ONCE(jiffies_scan_wait);
1571
1572		mutex_lock(&scan_mutex);
1573		kmemleak_scan();
1574		mutex_unlock(&scan_mutex);
1575
1576		/* wait before the next scan */
1577		while (timeout && !kthread_should_stop())
1578			timeout = schedule_timeout_interruptible(timeout);
1579	}
1580
1581	pr_info("Automatic memory scanning thread ended\n");
1582
1583	return 0;
1584}
1585
1586/*
1587 * Start the automatic memory scanning thread. This function must be called
1588 * with the scan_mutex held.
1589 */
1590static void start_scan_thread(void)
1591{
1592	if (scan_thread)
1593		return;
1594	scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1595	if (IS_ERR(scan_thread)) {
1596		pr_warn("Failed to create the scan thread\n");
1597		scan_thread = NULL;
1598	}
1599}
1600
1601/*
1602 * Stop the automatic memory scanning thread.
 
1603 */
1604static void stop_scan_thread(void)
1605{
1606	if (scan_thread) {
1607		kthread_stop(scan_thread);
1608		scan_thread = NULL;
1609	}
1610}
1611
1612/*
1613 * Iterate over the object_list and return the first valid object at or after
1614 * the required position with its use_count incremented. The function triggers
1615 * a memory scanning when the pos argument points to the first position.
1616 */
1617static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1618{
1619	struct kmemleak_object *object;
1620	loff_t n = *pos;
1621	int err;
1622
1623	err = mutex_lock_interruptible(&scan_mutex);
1624	if (err < 0)
1625		return ERR_PTR(err);
1626
1627	rcu_read_lock();
1628	list_for_each_entry_rcu(object, &object_list, object_list) {
1629		if (n-- > 0)
1630			continue;
1631		if (get_object(object))
1632			goto out;
1633	}
1634	object = NULL;
1635out:
1636	return object;
1637}
1638
1639/*
1640 * Return the next object in the object_list. The function decrements the
1641 * use_count of the previous object and increases that of the next one.
1642 */
1643static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1644{
1645	struct kmemleak_object *prev_obj = v;
1646	struct kmemleak_object *next_obj = NULL;
1647	struct kmemleak_object *obj = prev_obj;
1648
1649	++(*pos);
1650
1651	list_for_each_entry_continue_rcu(obj, &object_list, object_list) {
1652		if (get_object(obj)) {
1653			next_obj = obj;
1654			break;
1655		}
1656	}
1657
1658	put_object(prev_obj);
1659	return next_obj;
1660}
1661
1662/*
1663 * Decrement the use_count of the last object required, if any.
1664 */
1665static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1666{
1667	if (!IS_ERR(v)) {
1668		/*
1669		 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1670		 * waiting was interrupted, so only release it if !IS_ERR.
1671		 */
1672		rcu_read_unlock();
1673		mutex_unlock(&scan_mutex);
1674		if (v)
1675			put_object(v);
1676	}
1677}
1678
1679/*
1680 * Print the information for an unreferenced object to the seq file.
1681 */
1682static int kmemleak_seq_show(struct seq_file *seq, void *v)
1683{
1684	struct kmemleak_object *object = v;
1685	unsigned long flags;
1686
1687	raw_spin_lock_irqsave(&object->lock, flags);
1688	if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
1689		print_unreferenced(seq, object);
1690	raw_spin_unlock_irqrestore(&object->lock, flags);
1691	return 0;
1692}
1693
1694static const struct seq_operations kmemleak_seq_ops = {
1695	.start = kmemleak_seq_start,
1696	.next  = kmemleak_seq_next,
1697	.stop  = kmemleak_seq_stop,
1698	.show  = kmemleak_seq_show,
1699};
1700
1701static int kmemleak_open(struct inode *inode, struct file *file)
1702{
1703	return seq_open(file, &kmemleak_seq_ops);
1704}
1705
1706static int dump_str_object_info(const char *str)
1707{
1708	unsigned long flags;
1709	struct kmemleak_object *object;
1710	unsigned long addr;
1711
1712	if (kstrtoul(str, 0, &addr))
1713		return -EINVAL;
1714	object = find_and_get_object(addr, 0);
1715	if (!object) {
1716		pr_info("Unknown object at 0x%08lx\n", addr);
1717		return -EINVAL;
1718	}
1719
1720	raw_spin_lock_irqsave(&object->lock, flags);
1721	dump_object_info(object);
1722	raw_spin_unlock_irqrestore(&object->lock, flags);
1723
1724	put_object(object);
1725	return 0;
1726}
1727
1728/*
1729 * We use grey instead of black to ensure we can do future scans on the same
1730 * objects. If we did not do future scans these black objects could
1731 * potentially contain references to newly allocated objects in the future and
1732 * we'd end up with false positives.
1733 */
1734static void kmemleak_clear(void)
1735{
1736	struct kmemleak_object *object;
1737	unsigned long flags;
1738
1739	rcu_read_lock();
1740	list_for_each_entry_rcu(object, &object_list, object_list) {
1741		raw_spin_lock_irqsave(&object->lock, flags);
1742		if ((object->flags & OBJECT_REPORTED) &&
1743		    unreferenced_object(object))
1744			__paint_it(object, KMEMLEAK_GREY);
1745		raw_spin_unlock_irqrestore(&object->lock, flags);
1746	}
1747	rcu_read_unlock();
1748
1749	kmemleak_found_leaks = false;
1750}
1751
1752static void __kmemleak_do_cleanup(void);
1753
1754/*
1755 * File write operation to configure kmemleak at run-time. The following
1756 * commands can be written to the /sys/kernel/debug/kmemleak file:
1757 *   off	- disable kmemleak (irreversible)
1758 *   stack=on	- enable the task stacks scanning
1759 *   stack=off	- disable the tasks stacks scanning
1760 *   scan=on	- start the automatic memory scanning thread
1761 *   scan=off	- stop the automatic memory scanning thread
1762 *   scan=...	- set the automatic memory scanning period in seconds (0 to
1763 *		  disable it)
1764 *   scan	- trigger a memory scan
1765 *   clear	- mark all current reported unreferenced kmemleak objects as
1766 *		  grey to ignore printing them, or free all kmemleak objects
1767 *		  if kmemleak has been disabled.
1768 *   dump=...	- dump information about the object found at the given address
1769 */
1770static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1771			      size_t size, loff_t *ppos)
1772{
1773	char buf[64];
1774	int buf_size;
1775	int ret;
1776
1777	buf_size = min(size, (sizeof(buf) - 1));
1778	if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1779		return -EFAULT;
1780	buf[buf_size] = 0;
1781
1782	ret = mutex_lock_interruptible(&scan_mutex);
1783	if (ret < 0)
1784		return ret;
1785
1786	if (strncmp(buf, "clear", 5) == 0) {
1787		if (kmemleak_enabled)
1788			kmemleak_clear();
1789		else
1790			__kmemleak_do_cleanup();
1791		goto out;
1792	}
1793
1794	if (!kmemleak_enabled) {
1795		ret = -EPERM;
1796		goto out;
1797	}
1798
1799	if (strncmp(buf, "off", 3) == 0)
1800		kmemleak_disable();
1801	else if (strncmp(buf, "stack=on", 8) == 0)
1802		kmemleak_stack_scan = 1;
1803	else if (strncmp(buf, "stack=off", 9) == 0)
1804		kmemleak_stack_scan = 0;
1805	else if (strncmp(buf, "scan=on", 7) == 0)
1806		start_scan_thread();
1807	else if (strncmp(buf, "scan=off", 8) == 0)
1808		stop_scan_thread();
1809	else if (strncmp(buf, "scan=", 5) == 0) {
1810		unsigned secs;
1811		unsigned long msecs;
1812
1813		ret = kstrtouint(buf + 5, 0, &secs);
1814		if (ret < 0)
1815			goto out;
1816
1817		msecs = secs * MSEC_PER_SEC;
1818		if (msecs > UINT_MAX)
1819			msecs = UINT_MAX;
1820
1821		stop_scan_thread();
1822		if (msecs) {
1823			WRITE_ONCE(jiffies_scan_wait, msecs_to_jiffies(msecs));
1824			start_scan_thread();
1825		}
1826	} else if (strncmp(buf, "scan", 4) == 0)
1827		kmemleak_scan();
1828	else if (strncmp(buf, "dump=", 5) == 0)
1829		ret = dump_str_object_info(buf + 5);
1830	else
1831		ret = -EINVAL;
1832
1833out:
1834	mutex_unlock(&scan_mutex);
1835	if (ret < 0)
1836		return ret;
1837
1838	/* ignore the rest of the buffer, only one command at a time */
1839	*ppos += size;
1840	return size;
1841}
1842
1843static const struct file_operations kmemleak_fops = {
1844	.owner		= THIS_MODULE,
1845	.open		= kmemleak_open,
1846	.read		= seq_read,
1847	.write		= kmemleak_write,
1848	.llseek		= seq_lseek,
1849	.release	= seq_release,
1850};
1851
1852static void __kmemleak_do_cleanup(void)
1853{
1854	struct kmemleak_object *object, *tmp;
1855
1856	/*
1857	 * Kmemleak has already been disabled, no need for RCU list traversal
1858	 * or kmemleak_lock held.
1859	 */
1860	list_for_each_entry_safe(object, tmp, &object_list, object_list) {
1861		__remove_object(object);
1862		__delete_object(object);
1863	}
1864}
1865
1866/*
1867 * Stop the memory scanning thread and free the kmemleak internal objects if
1868 * no previous scan thread (otherwise, kmemleak may still have some useful
1869 * information on memory leaks).
1870 */
1871static void kmemleak_do_cleanup(struct work_struct *work)
1872{
1873	stop_scan_thread();
1874
1875	mutex_lock(&scan_mutex);
1876	/*
1877	 * Once it is made sure that kmemleak_scan has stopped, it is safe to no
1878	 * longer track object freeing. Ordering of the scan thread stopping and
1879	 * the memory accesses below is guaranteed by the kthread_stop()
1880	 * function.
1881	 */
1882	kmemleak_free_enabled = 0;
1883	mutex_unlock(&scan_mutex);
1884
1885	if (!kmemleak_found_leaks)
1886		__kmemleak_do_cleanup();
1887	else
1888		pr_info("Kmemleak disabled without freeing internal data. Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\".\n");
 
 
1889}
1890
1891static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
1892
1893/*
1894 * Disable kmemleak. No memory allocation/freeing will be traced once this
1895 * function is called. Disabling kmemleak is an irreversible operation.
1896 */
1897static void kmemleak_disable(void)
1898{
1899	/* atomically check whether it was already invoked */
1900	if (cmpxchg(&kmemleak_error, 0, 1))
1901		return;
1902
1903	/* stop any memory operation tracing */
1904	kmemleak_enabled = 0;
1905
1906	/* check whether it is too early for a kernel thread */
1907	if (kmemleak_initialized)
1908		schedule_work(&cleanup_work);
1909	else
1910		kmemleak_free_enabled = 0;
1911
1912	pr_info("Kernel memory leak detector disabled\n");
1913}
1914
1915/*
1916 * Allow boot-time kmemleak disabling (enabled by default).
1917 */
1918static int __init kmemleak_boot_config(char *str)
1919{
1920	if (!str)
1921		return -EINVAL;
1922	if (strcmp(str, "off") == 0)
1923		kmemleak_disable();
1924	else if (strcmp(str, "on") == 0)
1925		kmemleak_skip_disable = 1;
1926	else
1927		return -EINVAL;
1928	return 0;
1929}
1930early_param("kmemleak", kmemleak_boot_config);
1931
 
 
 
 
 
 
 
 
 
 
 
1932/*
1933 * Kmemleak initialization.
1934 */
1935void __init kmemleak_init(void)
1936{
 
 
 
1937#ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1938	if (!kmemleak_skip_disable) {
 
1939		kmemleak_disable();
1940		return;
1941	}
1942#endif
1943
1944	if (kmemleak_error)
1945		return;
1946
1947	jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1948	jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1949
1950	object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1951	scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1952
1953	/* register the data/bss sections */
1954	create_object((unsigned long)_sdata, _edata - _sdata,
1955		      KMEMLEAK_GREY, GFP_ATOMIC);
1956	create_object((unsigned long)__bss_start, __bss_stop - __bss_start,
1957		      KMEMLEAK_GREY, GFP_ATOMIC);
1958	/* only register .data..ro_after_init if not within .data */
1959	if (&__start_ro_after_init < &_sdata || &__end_ro_after_init > &_edata)
1960		create_object((unsigned long)__start_ro_after_init,
1961			      __end_ro_after_init - __start_ro_after_init,
1962			      KMEMLEAK_GREY, GFP_ATOMIC);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1963}
1964
1965/*
1966 * Late initialization function.
1967 */
1968static int __init kmemleak_late_init(void)
1969{
1970	kmemleak_initialized = 1;
1971
1972	debugfs_create_file("kmemleak", 0644, NULL, NULL, &kmemleak_fops);
1973
1974	if (kmemleak_error) {
1975		/*
1976		 * Some error occurred and kmemleak was disabled. There is a
1977		 * small chance that kmemleak_disable() was called immediately
1978		 * after setting kmemleak_initialized and we may end up with
1979		 * two clean-up threads but serialized by scan_mutex.
1980		 */
1981		schedule_work(&cleanup_work);
1982		return -ENOMEM;
1983	}
1984
1985	if (IS_ENABLED(CONFIG_DEBUG_KMEMLEAK_AUTO_SCAN)) {
1986		mutex_lock(&scan_mutex);
1987		start_scan_thread();
1988		mutex_unlock(&scan_mutex);
1989	}
 
 
1990
1991	pr_info("Kernel memory leak detector initialized (mem pool available: %d)\n",
1992		mem_pool_free_count);
1993
1994	return 0;
1995}
1996late_initcall(kmemleak_late_init);