From: Zeng Zhaoming <zengzm.kernel@xxxxxxxxx> please check the discuss with allocator guys. http://marc.info/?l=linux-kernel&m=129004890020256&w=2 Get a memory leak about ext4: comm "mount", pid 1159, jiffies 4294904647 (age 6077.804s) hex dump (first 32 bytes): 65 78 74 34 5f 67 72 6f 75 70 69 6e 66 6f 5f 31 ext4_groupinfo_1 30 00 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 0.kkkkkkkkkkkkk. backtrace: [<c068ade3>] kmemleak_alloc+0x93/0xd0 [<c024e54c>] __kmalloc_track_caller+0x30c/0x380 [<c02269d3>] kstrdup+0x33/0x60 [<c0318a70>] ext4_mb_init+0x4e0/0x550 [<c0304e0e>] ext4_fill_super+0x1e6e/0x2f60 [<c0261140>] mount_bdev+0x1c0/0x1f0 [<c02fc00f>] ext4_mount+0x1f/0x30 [<c02603d8>] vfs_kern_mount+0x78/0x250 [<c026060e>] do_kern_mount+0x3e/0x100 [<c027b4c2>] do_mount+0x2e2/0x780 [<c027ba04>] sys_mount+0xa4/0xd0 [<c010429f>] sysenter_do_call+0x12/0x38 [<ffffffff>] 0xffffffff ext4 allocate memory for cache name by: namep = kstrdup(name, GFP_KERNEL); and reclaim it by: name = kmem_cache_name(cache); kfree(name) This is ok if allocator only reference to the cache name memory, and return the name memory pass to kmem_cache_create() by kmem_cache_name(); But not true in slub, when using slub, memory leak and double free error appears. In this patch, we track the cache name memory in ext4, rather than allocator. Signed-off-by: Zeng Zhaoming <zengzm.kernel@xxxxxxxxx> --- fs/ext4/mballoc.c | 24 ++++++++++++++++-------- 1 files changed, 16 insertions(+), 8 deletions(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 5b4d4e3..c744661 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -344,7 +344,13 @@ static struct kmem_cache *ext4_free_ext_cachep; * each unique s_blocksize_bits */ #define NR_GRPINFO_CACHES \ (EXT4_MAX_BLOCK_LOG_SIZE - EXT4_MIN_BLOCK_LOG_SIZE + 1) -static struct kmem_cache *ext4_groupinfo_caches[NR_GRPINFO_CACHES]; + +static struct { + /* memory cache */ + struct kmem_cache *cache; + /* name of the cache */ + char* cache_name; +} ext4_groupinfo_caches[NR_GRPINFO_CACHES]; static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap, ext4_group_t group); @@ -2245,7 +2251,7 @@ static const struct file_operations ext4_mb_seq_groups_fops = { static struct kmem_cache *get_groupinfo_cache(int blocksize_bits) { int cache_index = blocksize_bits - EXT4_MIN_BLOCK_LOG_SIZE; - struct kmem_cache *cachep = ext4_groupinfo_caches[cache_index]; + struct kmem_cache *cachep = ext4_groupinfo_caches[cache_index].cache; BUG_ON(!cachep); return cachep; @@ -2441,7 +2447,7 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery) } cache_index = sb->s_blocksize_bits - EXT4_MIN_BLOCK_LOG_SIZE; - cachep = ext4_groupinfo_caches[cache_index]; + cachep = ext4_groupinfo_caches[cache_index].cache; if (!cachep) { char name[32]; int len = offsetof(struct ext4_group_info, @@ -2462,7 +2468,8 @@ int ext4_mb_init(struct super_block *sb, int needs_recovery) ret = -ENOMEM; goto out; } - ext4_groupinfo_caches[cache_index] = cachep; + ext4_groupinfo_caches[cache_index].cache = cachep; + ext4_groupinfo_caches[cache_index].cache_name = namep; } /* order 0 is regular bitmap */ @@ -2745,12 +2752,13 @@ void ext4_exit_mballoc(void) kmem_cache_destroy(ext4_free_ext_cachep); for (i = 0; i < NR_GRPINFO_CACHES; i++) { - struct kmem_cache *cachep = ext4_groupinfo_caches[i]; - if (cachep) { - char *name = (char *)kmem_cache_name(cachep); + struct kmem_cache *cachep = ext4_groupinfo_caches[i].cache; + char *name = ext4_groupinfo_caches[i].cache_name; + + if (cachep) kmem_cache_destroy(cachep); + if (name) kfree(name); - } } ext4_remove_debugfs_entry(); } -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
