diff options
Diffstat (limited to 'mm/kmemleak.c')
| -rw-r--r-- | mm/kmemleak.c | 743 |
1 files changed, 464 insertions, 279 deletions
diff --git a/mm/kmemleak.c b/mm/kmemleak.c index ec759b60077..4ea4510e299 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -48,10 +48,10 @@ * scanned. This list is only modified during a scanning episode when the * scan_mutex is held. At the end of a scan, the gray_list is always empty. * Note that the kmemleak_object.use_count is incremented when an object is - * added to the gray_list and therefore cannot be freed - * - kmemleak_mutex (mutex): prevents multiple users of the "kmemleak" debugfs - * file together with modifications to the memory scanning parameters - * including the scan_thread pointer + * added to the gray_list and therefore cannot be freed. This mutex also + * prevents multiple users of the "kmemleak" debugfs file together with + * modifications to the memory scanning parameters including the scan_thread + * pointer * * The kmemleak_object structures have a use_count incremented or decremented * using the get_object()/put_object() functions. When the use_count becomes @@ -61,6 +61,8 @@ * structure. */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + #include <linux/init.h> #include <linux/kernel.h> #include <linux/list.h> @@ -90,22 +92,24 @@ #include <linux/string.h> #include <linux/nodemask.h> #include <linux/mm.h> +#include <linux/workqueue.h> #include <asm/sections.h> #include <asm/processor.h> #include <asm/atomic.h> +#include <linux/kmemcheck.h> #include <linux/kmemleak.h> /* * Kmemleak configuration and common defines. */ #define MAX_TRACE 16 /* stack trace length */ -#define REPORTS_NR 50 /* maximum number of reported leaks */ #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */ -#define MSECS_SCAN_YIELD 10 /* CPU yielding period */ #define SECS_FIRST_SCAN 60 /* delay before the first scan */ #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */ +#define GRAY_LIST_PASSES 25 /* maximum number of gray list scans */ +#define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */ #define BYTES_PER_POINTER sizeof(void *) @@ -119,6 +123,9 @@ struct kmemleak_scan_area { size_t length; }; +#define KMEMLEAK_GREY 0 +#define KMEMLEAK_BLACK -1 + /* * Structure holding the metadata for each allocated memory block. * Modifications to such objects should be made while holding the @@ -157,6 +164,17 @@ struct kmemleak_object { #define OBJECT_REPORTED (1 << 1) /* flag set to not scan the object */ #define OBJECT_NO_SCAN (1 << 2) +/* flag set on newly allocated objects */ +#define OBJECT_NEW (1 << 3) + +/* number of bytes to print per line; must be 16 or 32 */ +#define HEX_ROW_SIZE 16 +/* number of bytes to print at a time (1, 2, 4, 8) */ +#define HEX_GROUP_SIZE 1 +/* include ASCII after the hex output */ +#define HEX_ASCII 1 +/* max number of lines to be printed */ +#define HEX_MAX_LINES 2 /* the list of all allocated objects */ static LIST_HEAD(object_list); @@ -184,22 +202,16 @@ static atomic_t kmemleak_error = ATOMIC_INIT(0); static unsigned long min_addr = ULONG_MAX; static unsigned long max_addr; -/* used for yielding the CPU to other tasks during scanning */ -static unsigned long next_scan_yield; static struct task_struct *scan_thread; -static unsigned long jiffies_scan_yield; +/* used to avoid reporting of recently allocated objects */ static unsigned long jiffies_min_age; +static unsigned long jiffies_last_scan; /* delay between automatic memory scannings */ static signed long jiffies_scan_wait; /* enables or disables the task stacks scanning */ -static int kmemleak_stack_scan; -/* mutex protecting the memory scanning */ +static int kmemleak_stack_scan = 1; +/* protects the memory scanning, parameters and debug/kmemleak file access */ static DEFINE_MUTEX(scan_mutex); -/* mutex protecting the access to the /sys/kernel/debug/kmemleak file */ -static DEFINE_MUTEX(kmemleak_mutex); - -/* number of leaks reported (for limitation purposes) */ -static int reported_leaks; /* * Early object allocation/freeing logging. Kmemleak is initialized after the @@ -213,6 +225,7 @@ static int reported_leaks; enum { KMEMLEAK_ALLOC, KMEMLEAK_FREE, + KMEMLEAK_FREE_PART, KMEMLEAK_NOT_LEAK, KMEMLEAK_IGNORE, KMEMLEAK_SCAN_AREA, @@ -230,11 +243,14 @@ struct early_log { int min_count; /* minimum reference count */ unsigned long offset; /* scan area offset */ size_t length; /* scan area length */ + unsigned long trace[MAX_TRACE]; /* stack trace */ + unsigned int trace_len; /* stack trace length */ }; /* early logging buffer and current position */ -static struct early_log early_log[200]; -static int crt_early_log; +static struct early_log + early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata; +static int crt_early_log __initdata; static void kmemleak_disable(void); @@ -257,6 +273,35 @@ static void kmemleak_disable(void); } while (0) /* + * Printing of the objects hex dump to the seq file. The number of lines to be + * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The + * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called + * with the object->lock held. + */ +static void hex_dump_object(struct seq_file *seq, + struct kmemleak_object *object) +{ + const u8 *ptr = (const u8 *)object->pointer; + int i, len, remaining; + unsigned char linebuf[HEX_ROW_SIZE * 5]; + + /* limit the number of lines to HEX_MAX_LINES */ + remaining = len = + min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE)); + + seq_printf(seq, " hex dump (first %d bytes):\n", len); + for (i = 0; i < len; i += HEX_ROW_SIZE) { + int linelen = min(remaining, HEX_ROW_SIZE); + + remaining -= HEX_ROW_SIZE; + hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE, + HEX_GROUP_SIZE, linebuf, sizeof(linebuf), + HEX_ASCII); + seq_printf(seq, " %s\n", linebuf); + } +} + +/* * Object colors, encoded with count and min_count: * - white - orphan object, not enough references to it (count < min_count) * - gray - not orphan, not marked as false positive (min_count == 0) or @@ -266,23 +311,21 @@ static void kmemleak_disable(void); * Newly created objects don't have any color assigned (object->count == -1) * before the next memory scan when they become white. */ -static int color_white(const struct kmemleak_object *object) +static bool color_white(const struct kmemleak_object *object) { - return object->count != -1 && object->count < object->min_count; + return object->count != KMEMLEAK_BLACK && + object->count < object->min_count; } -static int color_gray(const struct kmemleak_object *object) +static bool color_gray(const struct kmemleak_object *object) { - return object->min_count != -1 && object->count >= object->min_count; + return object->min_count != KMEMLEAK_BLACK && + object->count >= object->min_count; } -/* - * Objects are considered referenced if their color is gray and they have not - * been deleted. - */ -static int referenced_object(struct kmemleak_object *object) +static bool color_black(const struct kmemleak_object *object) { - return (object->flags & OBJECT_ALLOCATED) && color_gray(object); + return object->min_count == KMEMLEAK_BLACK; } /* @@ -290,45 +333,32 @@ static int referenced_object(struct kmemleak_object *object) * not be deleted and have a minimum age to avoid false positives caused by * pointers temporarily stored in CPU registers. */ -static int unreferenced_object(struct kmemleak_object *object) +static bool unreferenced_object(struct kmemleak_object *object) { return (object->flags & OBJECT_ALLOCATED) && color_white(object) && - time_is_before_eq_jiffies(object->jiffies + jiffies_min_age); + time_before_eq(object->jiffies + jiffies_min_age, + jiffies_last_scan); } /* - * Printing of the (un)referenced objects information, either to the seq file - * or to the kernel log. The print_referenced/print_unreferenced functions - * must be called with the object->lock held. + * Printing of the unreferenced objects information to the seq file. The + * print_unreferenced function must be called with the object->lock held. */ -#define print_helper(seq, x...) do { \ - struct seq_file *s = (seq); \ - if (s) \ - seq_printf(s, x); \ - else \ - pr_info(x); \ -} while (0) - -static void print_referenced(struct kmemleak_object *object) -{ - pr_info("kmemleak: referenced object 0x%08lx (size %zu)\n", - object->pointer, object->size); -} - static void print_unreferenced(struct seq_file *seq, struct kmemleak_object *object) { int i; - print_helper(seq, "kmemleak: unreferenced object 0x%08lx (size %zu):\n", - object->pointer, object->size); - print_helper(seq, " comm \"%s\", pid %d, jiffies %lu\n", - object->comm, object->pid, object->jiffies); - print_helper(seq, " backtrace:\n"); + seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n", + object->pointer, object->size); + seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu\n", + object->comm, object->pid, object->jiffies); + hex_dump_object(seq, object); + seq_printf(seq, " backtrace:\n"); for (i = 0; i < object->trace_len; i++) { void *ptr = (void *)object->trace[i]; - print_helper(seq, " [<%p>] %pS\n", ptr, ptr); + seq_printf(seq, " [<%p>] %pS\n", ptr, ptr); } } @@ -344,12 +374,13 @@ static void dump_object_info(struct kmemleak_object *object) trace.nr_entries = object->trace_len; trace.entries = object->trace; - pr_notice("kmemleak: Object 0x%08lx (size %zu):\n", + pr_notice("Object 0x%08lx (size %zu):\n", object->tree_node.start, object->size); pr_notice(" comm \"%s\", pid %d, jiffies %lu\n", object->comm, object->pid, object->jiffies); pr_notice(" min_count = %d\n", object->min_count); pr_notice(" count = %d\n", object->count); + pr_notice(" flags = 0x%lx\n", object->flags); pr_notice(" backtrace:\n"); print_stack_trace(&trace, 4); } @@ -372,7 +403,7 @@ static struct kmemleak_object *lookup_object(unsigned long ptr, int alias) object = prio_tree_entry(node, struct kmemleak_object, tree_node); if (!alias && object->pointer != ptr) { - kmemleak_warn("kmemleak: Found object by alias"); + kmemleak_warn("Found object by alias"); object = NULL; } } else @@ -454,22 +485,36 @@ static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias) } /* + * Save stack trace to the given array of MAX_TRACE size. + */ +static int __save_stack_trace(unsigned long *trace) +{ + struct stack_trace stack_trace; + + stack_trace.max_entries = MAX_TRACE; + stack_trace.nr_entries = 0; + stack_trace.entries = trace; + stack_trace.skip = 2; + save_stack_trace(&stack_trace); + + return stack_trace.nr_entries; +} + +/* * Create the metadata (struct kmemleak_object) corresponding to an allocated * memory block and add it to the object_list and object_tree_root. */ -static void create_object(unsigned long ptr, size_t size, int min_count, - gfp_t gfp) +static struct kmemleak_object *create_object(unsigned long ptr, size_t size, + int min_count, gfp_t gfp) { unsigned long flags; struct kmemleak_object *object; struct prio_tree_node *node; - struct stack_trace trace; object = kmem_cache_alloc(object_cache, gfp & GFP_KMEMLEAK_MASK); if (!object) { - kmemleak_stop("kmemleak: Cannot allocate a kmemleak_object " - "structure\n"); - return; + kmemleak_stop("Cannot allocate a kmemleak_object structure\n"); + return NULL; } INIT_LIST_HEAD(&object->object_list); @@ -477,7 +522,7 @@ static void create_object(unsigned long ptr, size_t size, int min_count, INIT_HLIST_HEAD(&object->area_list); spin_lock_init(&object->lock); atomic_set(&object->use_count, 1); - object->flags = OBJECT_ALLOCATED; + object->flags = OBJECT_ALLOCATED | OBJECT_NEW; object->pointer = ptr; object->size = size; object->min_count = min_count; @@ -503,18 +548,14 @@ static void create_object(unsigned long ptr, size_t size, int min_count, } /* kernel backtrace */ - trace.max_entries = MAX_TRACE; - trace.nr_entries = 0; - trace.entries = object->trace; - trace.skip = 1; - save_stack_trace(&trace); - object->trace_len = trace.nr_entries; + object->trace_len = __save_stack_trace(object->trace); INIT_PRIO_TREE_NODE(&object->tree_node); object->tree_node.start = ptr; object->tree_node.last = ptr + size - 1; write_lock_irqsave(&kmemleak_lock, flags); + min_addr = min(min_addr, ptr); max_addr = max(max_addr, ptr + size); node = prio_tree_insert(&object_tree_root, &object->tree_node); @@ -525,103 +566,157 @@ static void create_object(unsigned long ptr, size_t size, int min_count, * random memory blocks. */ if (node != &object->tree_node) { - unsigned long flags; - - kmemleak_stop("kmemleak: Cannot insert 0x%lx into the object " - "search tree (already existing)\n", ptr); + kmemleak_stop("Cannot insert 0x%lx into the object search tree " + "(already existing)\n", ptr); object = lookup_object(ptr, 1); - spin_lock_irqsave(&object->lock, flags); + spin_lock(&object->lock); dump_object_info(object); - spin_unlock_irqrestore(&object->lock, flags); + spin_unlock(&object->lock); goto out; } list_add_tail_rcu(&object->object_list, &object_list); out: write_unlock_irqrestore(&kmemleak_lock, flags); + return object; } /* * Remove the metadata (struct kmemleak_object) for a memory block from the * object_list and object_tree_root and decrement its use_count. */ -static void delete_object(unsigned long ptr) +static void __delete_object(struct kmemleak_object *object) { unsigned long flags; - struct kmemleak_object *object; write_lock_irqsave(&kmemleak_lock, flags); - object = lookup_object(ptr, 0); - if (!object) { - kmemleak_warn("kmemleak: Freeing unknown object at 0x%08lx\n", - ptr); - write_unlock_irqrestore(&kmemleak_lock, flags); - return; - } prio_tree_remove(&object_tree_root, &object->tree_node); list_del_rcu(&object->object_list); write_unlock_irqrestore(&kmemleak_lock, flags); WARN_ON(!(object->flags & OBJECT_ALLOCATED)); - WARN_ON(atomic_read(&object->use_count) < 1); + WARN_ON(atomic_read(&object->use_count) < 2); /* * Locking here also ensures that the corresponding memory block * cannot be freed when it is being scanned. */ spin_lock_irqsave(&object->lock, flags); - if (object->flags & OBJECT_REPORTED) - print_referenced(object); object->flags &= ~OBJECT_ALLOCATED; spin_unlock_irqrestore(&object->lock, flags); put_object(object); } /* - * Make a object permanently as gray-colored so that it can no longer be - * reported as a leak. This is used in general to mark a false positive. + * Look up the metadata (struct kmemleak_object) corresponding to ptr and + * delete it. */ -static void make_gray_object(unsigned long ptr) +static void delete_object_full(unsigned long ptr) { - unsigned long flags; struct kmemleak_object *object; object = find_and_get_object(ptr, 0); if (!object) { - kmemleak_warn("kmemleak: Graying unknown object at 0x%08lx\n", +#ifdef DEBUG + kmemleak_warn("Freeing unknown object at 0x%08lx\n", ptr); +#endif return; } - - spin_lock_irqsave(&object->lock, flags); - object->min_count = 0; - spin_unlock_irqrestore(&object->lock, flags); + __delete_object(object); put_object(object); } /* - * Mark the object as black-colored so that it is ignored from scans and - * reporting. + * Look up the metadata (struct kmemleak_object) corresponding to ptr and + * delete it. If the memory block is partially freed, the function may create + * additional metadata for the remaining parts of the block. */ -static void make_black_object(unsigned long ptr) +static void delete_object_part(unsigned long ptr, size_t size) { - unsigned long flags; struct kmemleak_object *object; + unsigned long start, end; - object = find_and_get_object(ptr, 0); + object = find_and_get_object(ptr, 1); if (!object) { - kmemleak_warn("kmemleak: Blacking unknown object at 0x%08lx\n", - ptr); +#ifdef DEBUG + kmemleak_warn("Partially freeing unknown object at 0x%08lx " + "(size %zu)\n", ptr, size); +#endif return; } + __delete_object(object); + + /* + * Create one or two objects that may result from the memory block + * split. Note that partial freeing is only done by free_bootmem() and + * this happens before kmemleak_init() is called. The path below is + * only executed during early log recording in kmemleak_init(), so + * GFP_KERNEL is enough. + */ + start = object->pointer; + end = object->pointer + object->size; + if (ptr > start) + create_object(start, ptr - start, object->min_count, + GFP_KERNEL); + if (ptr + size < end) + create_object(ptr + size, end - ptr - size, object->min_count, + GFP_KERNEL); + + put_object(object); +} + +static void __paint_it(struct kmemleak_object *object, int color) +{ + object->min_count = color; + if (color == KMEMLEAK_BLACK) + object->flags |= OBJECT_NO_SCAN; +} + +static void paint_it(struct kmemleak_object *object, int color) +{ + unsigned long flags; spin_lock_irqsave(&object->lock, flags); - object->min_count = -1; + __paint_it(object, color); spin_unlock_irqrestore(&object->lock, flags); +} + +static void paint_ptr(unsigned long ptr, int color) +{ + struct kmemleak_object *object; + + object = find_and_get_object(ptr, 0); + if (!object) { + kmemleak_warn("Trying to color unknown object " + "at 0x%08lx as %s\n", ptr, + (color == KMEMLEAK_GREY) ? "Grey" : + (color == KMEMLEAK_BLACK) ? "Black" : "Unknown"); + return; + } + paint_it(object, color); put_object(object); } /* + * Make a object permanently as gray-colored so that it can no longer be + * reported as a leak. This is used in general to mark a false positive. + */ +static void make_gray_object(unsigned long ptr) +{ + paint_ptr(ptr, KMEMLEAK_GREY); +} + +/* + * Mark the object as black-colored so that it is ignored from scans and + * reporting. + */ +static void make_black_object(unsigned long ptr) +{ + paint_ptr(ptr, KMEMLEAK_BLACK); +} + +/* * Add a scanning area to the object. If at least one such area is added, * kmemleak will only scan these ranges rather than the whole memory block. */ @@ -634,21 +729,20 @@ static void add_scan_area(unsigned long ptr, unsigned long offset, object = find_and_get_object(ptr, 0); if (!object) { - kmemleak_warn("kmemleak: Adding scan area to unknown " - "object at 0x%08lx\n", ptr); + kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n", + ptr); return; } area = kmem_cache_alloc(scan_area_cache, gfp & GFP_KMEMLEAK_MASK); if (!area) { - kmemleak_warn("kmemleak: Cannot allocate a scan area\n"); + kmemleak_warn("Cannot allocate a scan area\n"); goto out; } spin_lock_irqsave(&object->lock, flags); if (offset + length > object->size) { - kmemleak_warn("kmemleak: Scan area larger than object " - "0x%08lx\n", ptr); + kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr); dump_object_info(object); kmem_cache_free(scan_area_cache, area); goto out_unlock; @@ -677,8 +771,7 @@ static void object_no_scan(unsigned long ptr) object = find_and_get_object(ptr, 0); if (!object) { - kmemleak_warn("kmemleak: Not scanning unknown object at " - "0x%08lx\n", ptr); + kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr); return; } @@ -692,14 +785,16 @@ static void object_no_scan(unsigned long ptr) * Log an early kmemleak_* call to the early_log buffer. These calls will be * processed later once kmemleak is fully initialized. */ -static void log_early(int op_type, const void *ptr, size_t size, - int min_count, unsigned long offset, size_t length) +static void __init log_early(int op_type, const void *ptr, size_t size, + int min_count, unsigned long offset, size_t length) { unsigned long flags; struct early_log *log; if (crt_early_log >= ARRAY_SIZE(early_log)) { - kmemleak_stop("kmemleak: Early log buffer exceeded\n"); + pr_warning("Early log buffer exceeded, " + "please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n"); + kmemleak_disable(); return; } @@ -715,16 +810,45 @@ static void log_early(int op_type, const void *ptr, size_t size, log->min_count = min_count; log->offset = offset; log->length = length; + if (op_type == KMEMLEAK_ALLOC) + log->trace_len = __save_stack_trace(log->trace); crt_early_log++; local_irq_restore(flags); } /* + * Log an early allocated block and populate the stack trace. + */ +static void early_alloc(struct early_log *log) +{ + struct kmemleak_object *object; + unsigned long flags; + int i; + + if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr)) + return; + + /* + * RCU locking needed to ensure object is not freed via put_object(). + */ + rcu_read_lock(); + object = create_object((unsigned long)log->ptr, log->size, + log->min_count, GFP_KERNEL); + spin_lock_irqsave(&object->lock, flags); + for (i = 0; i < log->trace_len; i++) + object->trace[i] = log->trace[i]; + object->trace_len = log->trace_len; + spin_unlock_irqrestore(&object->lock, flags); + rcu_read_unlock(); +} + +/* * Memory allocation function callback. This function is called from the * kernel allocators when a new block is allocated (kmem_cache_alloc, kmalloc, * vmalloc etc.). */ -void kmemleak_alloc(const void *ptr, size_t size, int min_count, gfp_t gfp) +void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count, + gfp_t gfp) { pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count); @@ -739,22 +863,37 @@ EXPORT_SYMBOL_GPL(kmemleak_alloc); * Memory freeing function callback. This function is called from the kernel * allocators when a block is freed (kmem_cache_free, kfree, vfree etc.). */ -void kmemleak_free(const void *ptr) +void __ref kmemleak_free(const void *ptr) { pr_debug("%s(0x%p)\n", __func__, ptr); if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) - delete_object((unsigned long)ptr); + delete_object_full((unsigned long)ptr); else if (atomic_read(&kmemleak_early_log)) log_early(KMEMLEAK_FREE, ptr, 0, 0, 0, 0); } EXPORT_SYMBOL_GPL(kmemleak_free); /* + * Partial memory freeing function callback. This function is usually called + * from bootmem allocator when (part of) a memory block is freed. + */ +void __ref kmemleak_free_part(const void *ptr, size_t size) +{ + pr_debug("%s(0x%p)\n", __func__, ptr); + + if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr)) + delete_object_part((unsigned long)ptr, size); + else if (atomic_read(&kmemleak_early_log)) + log_early(KMEMLEAK_FREE_PART, ptr, size, 0, 0, 0); +} +EXPORT_SYMBOL_GPL(kmemleak_free_part); + +/* * Mark an already allocated memory block as a false positive. This will cause * the block to no longer be reported as leak and always be scanned. */ -void kmemleak_not_leak(const void *ptr) +void __ref kmemleak_not_leak(const void *ptr) { pr_debug("%s(0x%p)\n", __func__, ptr); @@ -770,7 +909,7 @@ EXPORT_SYMBOL(kmemleak_not_leak); * corresponding block is not a leak and does not contain any references to * other allocated memory blocks. */ -void kmemleak_ignore(const void *ptr) +void __ref kmemleak_ignore(const void *ptr) { pr_debug("%s(0x%p)\n", __func__, ptr); @@ -784,8 +923,8 @@ EXPORT_SYMBOL(kmemleak_ignore); /* * Limit the range to be scanned in an allocated memory block. */ -void kmemleak_scan_area(const void *ptr, unsigned long offset, size_t length, - gfp_t gfp) +void __ref kmemleak_scan_area(const void *ptr, unsigned long offset, + size_t length, gfp_t gfp) { pr_debug("%s(0x%p)\n", __func__, ptr); @@ -799,7 +938,7 @@ EXPORT_SYMBOL(kmemleak_scan_area); /* * Inform kmemleak not to scan the given memory block. */ -void kmemleak_no_scan(const void *ptr) +void __ref kmemleak_no_scan(const void *ptr) { pr_debug("%s(0x%p)\n", __func__, ptr); @@ -811,21 +950,6 @@ void kmemleak_no_scan(const void *ptr) EXPORT_SYMBOL(kmemleak_no_scan); /* - * Yield the CPU so that other tasks get a chance to run. The yielding is - * rate-limited to avoid excessive number of calls to the schedule() function - * during memory scanning. - */ -static void scan_yield(void) -{ - might_sleep(); - - if (time_is_before_eq_jiffies(next_scan_yield)) { - schedule(); - next_scan_yield = jiffies + jiffies_scan_yield; - } -} - -/* * Memory scanning is a long process and it needs to be interruptable. This * function checks whether such interrupt condition occured. */ @@ -851,28 +975,28 @@ static int scan_should_stop(void) * found to the gray list. */ static void scan_block(void *_start, void *_end, - struct kmemleak_object *scanned) + struct kmemleak_object *scanned, int allow_resched) { unsigned long *ptr; unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER); unsigned long *end = _end - (BYTES_PER_POINTER - 1); for (ptr = start; ptr < end; ptr++) { - unsigned long flags; - unsigned long pointer = *ptr; struct kmemleak_object *object; + unsigned long flags; + unsigned long pointer; + if (allow_resched) + cond_resched(); if (scan_should_stop()) break; - /* - * When scanning a memory block with a corresponding - * kmemleak_object, the CPU yielding is handled in the calling - * code since it holds the object->lock to avoid the block - * freeing. - */ - if (!scanned) - scan_yield(); + /* don't scan uninitialized memory */ + if (!kmemcheck_is_obj_initialized((unsigned long)ptr, + BYTES_PER_POINTER)) + continue; + + pointer = *ptr; object = find_and_get_object(pointer, 1); if (!object) @@ -932,14 +1056,25 @@ static void scan_object(struct kmemleak_object *object) if (!(object->flags & OBJECT_ALLOCATED)) /* already freed object */ goto out; - if (hlist_empty(&object->area_list)) - scan_block((void *)object->pointer, - (void *)(object->pointer + object->size), object); - else + if (hlist_empty(&object->area_list)) { + void *start = (void *)object->pointer; + void *end = (void *)(object->pointer + object->size); + + while (start < end && (object->flags & OBJECT_ALLOCATED) && + !(object->flags & OBJECT_NO_SCAN)) { + scan_block(start, min(start + MAX_SCAN_SIZE, end), + object, 0); + start += MAX_SCAN_SIZE; + + spin_unlock_irqrestore(&object->lock, flags); + cond_resched(); + spin_lock_irqsave(&object->lock, flags); + } + } else hlist_for_each_entry(area, elem, &object->area_list, node) scan_block((void *)(object->pointer + area->offset), (void *)(object->pointer + area->offset - + area->length), object); + + area->length), object, 0); out: spin_unlock_irqrestore(&object->lock, flags); } @@ -953,8 +1088,11 @@ static void kmemleak_scan(void) { unsigned long flags; struct kmemleak_object *object, *tmp; - struct task_struct *task; int i; + int new_leaks = 0; + int gray_list_pass = 0; + + jiffies_last_scan = jiffies; /* prepare the kmemleak_object's */ rcu_read_lock(); @@ -966,13 +1104,14 @@ static void kmemleak_scan(void) * 1 reference to any object at this point. */ if (atomic_read(&object->use_count) > 1) { - pr_debug("kmemleak: object->use_count = %d\n", + pr_debug("object->use_count = %d\n", atomic_read(&object->use_count)); dump_object_info(object); } #endif /* reset the reference count (whiten the object) */ object->count = 0; + object->flags &= ~OBJECT_NEW; if (color_gray(object) && get_object(object)) list_add_tail(&object->gray_list, &gray_list); @@ -981,14 +1120,14 @@ static void kmemleak_scan(void) rcu_read_unlock(); /* data/bss scanning */ - scan_block(_sdata, _edata, NULL); - scan_block(__bss_start, __bss_stop, NULL); + scan_block(_sdata, _edata, NULL, 1); + scan_block(__bss_start, __bss_stop, NULL, 1); #ifdef CONFIG_SMP /* per-cpu sections scanning */ for_each_possible_cpu(i) scan_block(__per_cpu_start + per_cpu_offset(i), - __per_cpu_end + per_cpu_offset(i), NULL); + __per_cpu_end + per_cpu_offset(i), NULL, 1); #endif /* @@ -1010,19 +1149,21 @@ static void kmemleak_scan(void) /* only scan if page is in use */ if (page_count(page) == 0) continue; - scan_block(page, page + 1, NULL); + scan_block(page, page + 1, NULL, 1); } } /* - * Scanning the task stacks may introduce false negatives and it is - * not enabled by default. + * Scanning the task stacks (may introduce false negatives). */ if (kmemleak_stack_scan) { + struct task_struct *p, *g; + read_lock(&tasklist_lock); - for_each_process(task) - scan_block(task_stack_page(task), - task_stack_page(task) + THREAD_SIZE, NULL); + do_each_thread(g, p) { + scan_block(task_stack_page(p), task_stack_page(p) + + THREAD_SIZE, NULL, 0); + } while_each_thread(g, p); read_unlock(&tasklist_lock); } @@ -1034,9 +1175,10 @@ static void kmemleak_scan(void) * kmemleak objects cannot be freed from outside the loop because their * use_count was increased. */ +repeat: object = list_entry(gray_list.next, typeof(*object), gray_list); while (&object->gray_list != &gray_list) { - scan_yield(); + cond_resched(); /* may add new objects to the list */ if (!scan_should_stop()) @@ -1051,7 +1193,59 @@ static void kmemleak_scan(void) object = tmp; } + + if (scan_should_stop() || ++gray_list_pass >= GRAY_LIST_PASSES) + goto scan_end; + + /* + * Check for new objects allocated during this scanning and add them + * to the gray list. + */ + rcu_read_lock(); + list_for_each_entry_rcu(object, &object_list, object_list) { + spin_lock_irqsave(&object->lock, flags); + if ((object->flags & OBJECT_NEW) && !color_black(object) && + get_object(object)) { + object->flags &= ~OBJECT_NEW; + list_add_tail(&object->gray_list, &gray_list); + } + spin_unlock_irqrestore(&object->lock, flags); + } + rcu_read_unlock(); + + if (!list_empty(&gray_list)) + goto repeat; + +scan_end: WARN_ON(!list_empty(&gray_list)); + + /* + * If scanning was stopped or new objects were being allocated at a + * higher rate than gray list scanning, do not report any new + * unreferenced objects. + */ + if (scan_should_stop() || gray_list_pass >= GRAY_LIST_PASSES) + return; + + /* + * Scanning result reporting. + */ + rcu_read_lock(); + list_for_each_entry_rcu(object, &object_list, object_list) { + spin_lock_irqsave(&object->lock, flags); + if (unreferenced_object(object) && + !(object->flags & OBJECT_REPORTED)) { + object->flags |= OBJECT_REPORTED; + new_leaks++; + } + spin_unlock_irqrestore(&object->lock, flags); + } + rcu_read_unlock(); + + if (new_leaks) + pr_info("%d new suspected memory leaks (see " + "/sys/kernel/debug/kmemleak)\n", new_leaks); + } /* @@ -1062,7 +1256,8 @@ static int kmemleak_scan_thread(void *arg) { static int first_run = 1; - pr_info("kmemleak: Automatic memory scanning thread started\n"); + pr_info("Automatic memory scanning thread started\n"); + set_user_nice(current, 10); /* * Wait before the first scan to allow the system to fully initialize. @@ -1073,66 +1268,42 @@ static int kmemleak_scan_thread(void *arg) } while (!kthread_should_stop()) { - struct kmemleak_object *object; signed long timeout = jiffies_scan_wait; mutex_lock(&scan_mutex); - kmemleak_scan(); - reported_leaks = 0; - - rcu_read_lock(); - list_for_each_entry_rcu(object, &object_list, object_list) { - unsigned long flags; - - if (reported_leaks >= REPORTS_NR) - break; - spin_lock_irqsave(&object->lock, flags); - if (!(object->flags & OBJECT_REPORTED) && - unreferenced_object(object)) { - print_unreferenced(NULL, object); - object->flags |= OBJECT_REPORTED; - reported_leaks++; - } else if ((object->flags & OBJECT_REPORTED) && - referenced_object(object)) { - print_referenced(object); - object->flags &= ~OBJECT_REPORTED; - } - spin_unlock_irqrestore(&object->lock, flags); - } - rcu_read_unlock(); - mutex_unlock(&scan_mutex); + /* wait before the next scan */ while (timeout && !kthread_should_stop()) timeout = schedule_timeout_interruptible(timeout); } - pr_info("kmemleak: Automatic memory scanning thread ended\n"); + pr_info("Automatic memory scanning thread ended\n"); return 0; } /* * Start the automatic memory scanning thread. This function must be called - * with the kmemleak_mutex held. + * with the scan_mutex held. */ -void start_scan_thread(void) +static void start_scan_thread(void) { if (scan_thread) return; scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak"); if (IS_ERR(scan_thread)) { - pr_warning("kmemleak: Failed to create the scan thread\n"); + pr_warning("Failed to create the scan thread\n"); scan_thread = NULL; } } /* * Stop the automatic memory scanning thread. This function must be called - * with the kmemleak_mutex held. + * with the scan_mutex held. */ -void stop_scan_thread(void) +static void stop_scan_thread(void) { if (scan_thread) { kthread_stop(scan_thread); @@ -1149,13 +1320,11 @@ static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos) { struct kmemleak_object *object; loff_t n = *pos; + int err; - if (!n) { - kmemleak_scan(); - reported_leaks = 0; - } - if (reported_leaks >= REPORTS_NR) - return NULL; + err = mutex_lock_interruptible(&scan_mutex); + if (err < 0) + return ERR_PTR(err); rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) { @@ -1166,7 +1335,6 @@ static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos) } object = NULL; out: - rcu_read_unlock(); return object; } @@ -1181,17 +1349,13 @@ static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos) struct list_head *n = &prev_obj->object_list; ++(*pos); - if (reported_leaks >= REPORTS_NR) - goto out; - rcu_read_lock(); list_for_each_continue_rcu(n, &object_list) { next_obj = list_entry(n, struct kmemleak_object, object_list); if (get_object(next_obj)) break; } - rcu_read_unlock(); -out: + put_object(prev_obj); return next_obj; } @@ -1201,8 +1365,16 @@ out: */ static void kmemleak_seq_stop(struct seq_file *seq, void *v) { - if (v) - put_object(v); + if (!IS_ERR(v)) { + /* + * kmemleak_seq_start may return ERR_PTR if the scan_mutex + * waiting was interrupted, so only release it if !IS_ERR. + */ + rcu_read_unlock(); + mutex_unlock(&scan_mutex); + if (v) + put_object(v); + } } /* @@ -1214,11 +1386,8 @@ static int kmemleak_seq_show(struct seq_file *seq, void *v) unsigned long flags; spin_lock_irqsave(&object->lock, flags); - if (!unreferenced_object(object)) - goto out; - print_unreferenced(seq, object); - reported_leaks++; -out: + if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object)) + print_unreferenced(seq, object); spin_unlock_irqrestore(&object->lock, flags); return 0; } @@ -1232,43 +1401,58 @@ static const struct seq_operations kmemleak_seq_ops = { static int kmemleak_open(struct inode *inode, struct file *file) { - int ret = 0; - if (!atomic_read(&kmemleak_enabled)) return -EBUSY; - ret = mutex_lock_interruptible(&kmemleak_mutex); - if (ret < 0) - goto out; - if (file->f_mode & FMODE_READ) { - ret = mutex_lock_interruptible(&scan_mutex); - if (ret < 0) - goto kmemleak_unlock; - ret = seq_open(file, &kmemleak_seq_ops); - if (ret < 0) - goto scan_unlock; - } - return ret; - -scan_unlock: - mutex_unlock(&scan_mutex); -kmemleak_unlock: - mutex_unlock(&kmemleak_mutex); -out: - return ret; + return seq_open(file, &kmemleak_seq_ops); } static int kmemleak_release(struct inode *inode, struct file *file) { - int ret = 0; + return seq_release(inode, file); +} - if (file->f_mode & FMODE_READ) { - seq_release(inode, file); - mutex_unlock(&scan_mutex); +static int dump_str_object_info(const char *str) +{ + unsigned long flags; + struct kmemleak_object *object; + unsigned long addr; + + addr= simple_strtoul(str, NULL, 0); + object = find_and_get_object(addr, 0); + if (!object) { + pr_info("Unknown object at 0x%08lx\n", addr); + return -EINVAL; } - mutex_unlock(&kmemleak_mutex); - return ret; + spin_lock_irqsave(&object->lock, flags); + dump_object_info(object); + spin_unlock_irqrestore(&object->lock, flags); + + put_object(object); + return 0; +} + +/* + * We use grey instead of black to ensure we can do future scans on the same + * objects. If we did not do future scans these black objects could + * potentially contain references to newly allocated objects in the future and + * we'd end up with false positives. + */ +static void kmemleak_clear(void) +{ + struct kmemleak_object *object; + unsigned long flags; + + rcu_read_lock(); + list_for_each_entry_rcu(object, &object_list, object_list) { + spin_lock_irqsave(&object->lock, flags); + if ((object->flags & OBJECT_REPORTED) && + unreferenced_object(object)) + __paint_it(object, KMEMLEAK_GREY); + spin_unlock_irqrestore(&object->lock, flags); + } + rcu_read_unlock(); } /* @@ -1281,21 +1465,27 @@ static int kmemleak_release(struct inode *inode, struct file *file) * scan=off - stop the automatic memory scanning thread * scan=... - set the automatic memory scanning period in seconds (0 to * disable it) + * scan - trigger a memory scan + * clear - mark all current reported unreferenced kmemleak objects as + * grey to ignore printing them + * dump=... - dump information about the object found at the given address */ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf, size_t size, loff_t *ppos) { char buf[64]; int buf_size; - - if (!atomic_read(&kmemleak_enabled)) - return -EBUSY; + int ret; buf_size = min(size, (sizeof(buf) - 1)); if (strncpy_from_user(buf, user_buf, buf_size) < 0) return -EFAULT; buf[buf_size] = 0; + ret = mutex_lock_interruptible(&scan_mutex); + if (ret < 0) + return ret; + if (strncmp(buf, "off", 3) == 0) kmemleak_disable(); else if (strncmp(buf, "stack=on", 8) == 0) @@ -1308,18 +1498,28 @@ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf, stop_scan_thread(); else if (strncmp(buf, "scan=", 5) == 0) { unsigned long secs; - int err; - err = strict_strtoul(buf + 5, 0, &secs); - if (err < 0) - return err; + ret = strict_strtoul(buf + 5, 0, &secs); + if (ret < 0) + goto out; stop_scan_thread(); if (secs) { jiffies_scan_wait = msecs_to_jiffies(secs * 1000); start_scan_thread(); } - } else - return -EINVAL; + } else if (strncmp(buf, "scan", 4) == 0) + kmemleak_scan(); + else if (strncmp(buf, "clear", 5) == 0) + kmemleak_clear(); + else if (strncmp(buf, "dump=", 5) == 0) + ret = dump_str_object_info(buf + 5); + else + ret = -EINVAL; + +out: + mutex_unlock(&scan_mutex); + if (ret < 0) + return ret; /* ignore the rest of the buffer, only one command at a time */ *ppos += size; @@ -1339,36 +1539,21 @@ static const struct file_operations kmemleak_fops = { * Perform the freeing of the kmemleak internal objects after waiting for any * current memory scan to complete. */ -static int kmemleak_cleanup_thread(void *arg) +static void kmemleak_do_cleanup(struct work_struct *work) { struct kmemleak_object *object; - mutex_lock(&kmemleak_mutex); + mutex_lock(&scan_mutex); stop_scan_thread(); - mutex_unlock(&kmemleak_mutex); - mutex_lock(&scan_mutex); rcu_read_lock(); list_for_each_entry_rcu(object, &object_list, object_list) - delete_object(object->pointer); + delete_object_full(object->pointer); rcu_read_unlock(); mutex_unlock(&scan_mutex); - - return 0; } -/* - * Start the clean-up thread. - */ -static void kmemleak_cleanup(void) -{ - struct task_struct *cleanup_thread; - - cleanup_thread = kthread_run(kmemleak_cleanup_thread, NULL, - "kmemleak-clean"); - if (IS_ERR(cleanup_thread)) - pr_warning("kmemleak: Failed to create the clean-up thread\n"); -} +static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup); /* * Disable kmemleak. No memory allocation/freeing will be traced once this @@ -1386,7 +1571,7 @@ static void kmemleak_disable(void) /* check whether it is too early for a kernel thread */ if (atomic_read(&kmemleak_initialized)) - kmemleak_cleanup(); + schedule_work(&cleanup_work); pr_info("Kernel memory leak detector disabled\n"); } @@ -1414,7 +1599,6 @@ void __init kmemleak_init(void) int i; unsigned long flags; - jiffies_scan_yield = msecs_to_jiffies(MSECS_SCAN_YIELD); jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE); jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000); @@ -1440,12 +1624,14 @@ void __init kmemleak_init(void) switch (log->op_type) { case KMEMLEAK_ALLOC: - kmemleak_alloc(log->ptr, log->size, log->min_count, - GFP_KERNEL); + early_alloc(log); break; case KMEMLEAK_FREE: kmemleak_free(log->ptr); break; + case KMEMLEAK_FREE_PART: + kmemleak_free_part(log->ptr, log->size); + break; case KMEMLEAK_NOT_LEAK: kmemleak_not_leak(log->ptr); break; @@ -1481,18 +1667,17 @@ static int __init kmemleak_late_init(void) * after setting kmemleak_initialized and we may end up with * two clean-up threads but serialized by scan_mutex. */ - kmemleak_cleanup(); + schedule_work(&cleanup_work); return -ENOMEM; } dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL, &kmemleak_fops); if (!dentry) - pr_warning("kmemleak: Failed to create the debugfs kmemleak " - "file\n"); - mutex_lock(&kmemleak_mutex); + pr_warning("Failed to create the debugfs kmemleak file\n"); + mutex_lock(&scan_mutex); start_scan_thread(); - mutex_unlock(&kmemleak_mutex); + mutex_unlock(&scan_mutex); pr_info("Kernel memory leak detector initialized\n"); |