diff options
| -rw-r--r-- | mm/kmemleak.c | 124 |
1 files changed, 70 insertions, 54 deletions
diff --git a/mm/kmemleak.c b/mm/kmemleak.c index ce79d91eeef7..002adc3cf3a1 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -93,6 +93,7 @@ #include <linux/nodemask.h> #include <linux/mm.h> #include <linux/workqueue.h> +#include <linux/crc32.h> #include <asm/sections.h> #include <asm/processor.h> @@ -108,7 +109,6 @@ #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */ #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 *) @@ -149,6 +149,8 @@ struct kmemleak_object { int min_count; /* the total number of pointers found pointing to this object */ int count; + /* checksum for detecting modified objects */ + u32 checksum; /* memory ranges to be scanned inside an object (empty for all) */ struct hlist_head area_list; unsigned long trace[MAX_TRACE]; @@ -164,8 +166,6 @@ 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 @@ -321,11 +321,6 @@ static bool color_gray(const struct kmemleak_object *object) object->count >= object->min_count; } -static bool color_black(const struct kmemleak_object *object) -{ - return object->min_count == KMEMLEAK_BLACK; -} - /* * Objects are considered unreferenced only if their color is white, they have * not be deleted and have a minimum age to avoid false positives caused by @@ -333,7 +328,7 @@ static bool color_black(const struct kmemleak_object *object) */ static bool unreferenced_object(struct kmemleak_object *object) { - return (object->flags & OBJECT_ALLOCATED) && color_white(object) && + return (color_white(object) && object->flags & OBJECT_ALLOCATED) && time_before_eq(object->jiffies + jiffies_min_age, jiffies_last_scan); } @@ -381,6 +376,7 @@ static void dump_object_info(struct kmemleak_object *object) 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(" checksum = %d\n", object->checksum); pr_notice(" backtrace:\n"); print_stack_trace(&trace, 4); } @@ -522,12 +518,13 @@ static struct kmemleak_object *create_object(unsigned long ptr, size_t size, INIT_HLIST_HEAD(&object->area_list); spin_lock_init(&object->lock); atomic_set(&object->use_count, 1); - object->flags = OBJECT_ALLOCATED | OBJECT_NEW; + object->flags = OBJECT_ALLOCATED; object->pointer = ptr; object->size = size; object->min_count = min_count; - object->count = -1; /* no color initially */ + object->count = 0; /* white color initially */ object->jiffies = jiffies; + object->checksum = 0; /* task information */ if (in_irq()) { @@ -949,6 +946,20 @@ void __ref kmemleak_no_scan(const void *ptr) EXPORT_SYMBOL(kmemleak_no_scan); /* + * Update an object's checksum and return true if it was modified. + */ +static bool update_checksum(struct kmemleak_object *object) +{ + u32 old_csum = object->checksum; + + if (!kmemcheck_is_obj_initialized(object->pointer, object->size)) + return false; + + object->checksum = crc32(0, (void *)object->pointer, object->size); + return object->checksum != old_csum; +} + +/* * Memory scanning is a long process and it needs to be interruptable. This * function checks whether such interrupt condition occured. */ @@ -1082,6 +1093,39 @@ out: } /* + * Scan the objects already referenced (gray objects). More objects will be + * referenced and, if there are no memory leaks, all the objects are scanned. + */ +static void scan_gray_list(void) +{ + struct kmemleak_object *object, *tmp; + + /* + * The list traversal is safe for both tail additions and removals + * from inside the loop. The kmemleak objects cannot be freed from + * outside the loop because their use_count was incremented. + */ + object = list_entry(gray_list.next, typeof(*object), gray_list); + while (&object->gray_list != &gray_list) { + cond_resched(); + + /* may add new objects to the list */ + if (!scan_should_stop()) + scan_object(object); + + tmp = list_entry(object->gray_list.next, typeof(*object), + gray_list); + + /* remove the object from the list and release it */ + list_del(&object->gray_list); + put_object(object); + + object = tmp; + } + WARN_ON(!list_empty(&gray_list)); +} + +/* * Scan data sections and all the referenced memory blocks allocated via the * kernel's standard allocators. This function must be called with the * scan_mutex held. @@ -1089,10 +1133,9 @@ out: static void kmemleak_scan(void) { unsigned long flags; - struct kmemleak_object *object, *tmp; + struct kmemleak_object *object; int i; int new_leaks = 0; - int gray_list_pass = 0; jiffies_last_scan = jiffies; @@ -1113,7 +1156,6 @@ static void kmemleak_scan(void) #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); @@ -1171,62 +1213,36 @@ static void kmemleak_scan(void) /* * Scan the objects already referenced from the sections scanned - * above. More objects will be referenced and, if there are no memory - * leaks, all the objects will be scanned. The list traversal is safe - * for both tail additions and removals from inside the loop. The - * kmemleak objects cannot be freed from outside the loop because their - * use_count was increased. + * above. */ -repeat: - object = list_entry(gray_list.next, typeof(*object), gray_list); - while (&object->gray_list != &gray_list) { - cond_resched(); - - /* may add new objects to the list */ - if (!scan_should_stop()) - scan_object(object); - - tmp = list_entry(object->gray_list.next, typeof(*object), - gray_list); - - /* remove the object from the list and release it */ - list_del(&object->gray_list); - put_object(object); - - object = tmp; - } - - if (scan_should_stop() || ++gray_list_pass >= GRAY_LIST_PASSES) - goto scan_end; + scan_gray_list(); /* - * Check for new objects allocated during this scanning and add them - * to the gray list. + * Check for new or unreferenced objects modified since the previous + * scan and color them gray until the next scan. */ 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; + if (color_white(object) && (object->flags & OBJECT_ALLOCATED) + && update_checksum(object) && get_object(object)) { + /* color it gray temporarily */ + object->count = object->min_count; 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)); + /* + * Re-scan the gray list for modified unreferenced objects. + */ + scan_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 scanning was stopped do not report any new unreferenced objects. */ - if (scan_should_stop() || gray_list_pass >= GRAY_LIST_PASSES) + if (scan_should_stop()) return; /* |