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Date: Mon, 22 Nov 2010 06:02:10 +0800
From: <zeng.zhaoming@...escale.com>
To: <linux-ext4@...r.kernel.org>
CC: <tytso@....edu>, <adilger.kernel@...ger.ca>, <mpm@...enic.com>,
<rientjes@...gle.com>, <penberg@...helsinki.fi>,
Zeng Zhaoming <zengzm.kernel@...il.com>
Subject: [PATCH] ext4: Fix memory leak in groupinfo cache name
From: Zeng Zhaoming <zengzm.kernel@...il.com>
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@...il.com>
---
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
--
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