From 53238a60dd4a679f6fe5613a7ed46899587205cf Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Tue, 7 Jul 2009 10:33:00 +0100 Subject: [PATCH] kmemleak: Allow partial freeing of memory blocks Functions like free_bootmem() are allowed to free only part of a memory block. This patch adds support for this via the kmemleak_free_part() callback which removes the original object and creates one or two additional objects as a result of the memory block split. Signed-off-by: Catalin Marinas Cc: Ingo Molnar Acked-by: Pekka Enberg --- include/linux/kmemleak.h | 4 ++ mm/kmemleak.c | 95 ++++++++++++++++++++++++++++++++++------ 2 files changed, 85 insertions(+), 14 deletions(-) diff --git a/include/linux/kmemleak.h b/include/linux/kmemleak.h index 7796aed6cdd5..6a63807f714e 100644 --- a/include/linux/kmemleak.h +++ b/include/linux/kmemleak.h @@ -27,6 +27,7 @@ extern void kmemleak_init(void); extern void kmemleak_alloc(const void *ptr, size_t size, int min_count, gfp_t gfp); extern void kmemleak_free(const void *ptr); +extern void kmemleak_free_part(const void *ptr, size_t size); extern void kmemleak_padding(const void *ptr, unsigned long offset, size_t size); extern void kmemleak_not_leak(const void *ptr); @@ -71,6 +72,9 @@ static inline void kmemleak_alloc_recursive(const void *ptr, size_t size, static inline void kmemleak_free(const void *ptr) { } +static inline void kmemleak_free_part(const void *ptr, size_t size) +{ +} static inline void kmemleak_free_recursive(const void *ptr, unsigned long flags) { } diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 466d39007264..5aabd41ffb8f 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -210,6 +210,7 @@ static DEFINE_MUTEX(scan_mutex); enum { KMEMLEAK_ALLOC, KMEMLEAK_FREE, + KMEMLEAK_FREE_PART, KMEMLEAK_NOT_LEAK, KMEMLEAK_IGNORE, KMEMLEAK_SCAN_AREA, @@ -523,27 +524,17 @@ static void create_object(unsigned long ptr, size_t size, int min_count, * 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) { -#ifdef DEBUG - kmemleak_warn("Freeing unknown object at 0x%08lx\n", - ptr); -#endif - 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 @@ -555,6 +546,64 @@ static void delete_object(unsigned long ptr) put_object(object); } +/* + * Look up the metadata (struct kmemleak_object) corresponding to ptr and + * delete it. + */ +static void delete_object_full(unsigned long ptr) +{ + struct kmemleak_object *object; + + object = find_and_get_object(ptr, 0); + if (!object) { +#ifdef DEBUG + kmemleak_warn("Freeing unknown object at 0x%08lx\n", + ptr); +#endif + return; + } + __delete_object(object); + put_object(object); +} + +/* + * 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 delete_object_part(unsigned long ptr, size_t size) +{ + struct kmemleak_object *object; + unsigned long start, end; + + object = find_and_get_object(ptr, 1); + if (!object) { +#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); +} /* * 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. @@ -719,12 +768,27 @@ void 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 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. @@ -1318,7 +1382,7 @@ static int kmemleak_cleanup_thread(void *arg) 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); @@ -1413,6 +1477,9 @@ void __init kmemleak_init(void) 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;