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Date: Sun, 28 Mar 2010 16:13:51 +0800
From: jing zhang <zj.barak@...il.com>
To: "Aneesh Kumar K. V" <aneesh.kumar@...ux.vnet.ibm.com>
Cc: tytso@....edu, linux-ext4 <linux-ext4@...r.kernel.org>,
Andreas Dilger <adilger@....com>,
Dave Kleikamp <shaggy@...ux.vnet.ibm.com>
Subject: Re: [PATCH] ext4: memory leakage in ext4_mb_init()
2010/3/26, Aneesh Kumar K. V <aneesh.kumar@...ux.vnet.ibm.com>:
> On Tue, 23 Mar 2010 20:47:39 +0800, jing zhang <zj.barak@...il.com> wrote:
>> 2010/3/22, tytso@....edu <tytso@....edu>:
>> > On Sun, Mar 21, 2010 at 10:01:06PM +0800, jing zhang wrote:
>> >> From: Jing Zhang <zj.barak@...il.com>
>> >>
>> >> Date: Sun Mar 21 21:59:35 2010
>> >>
>> >> Cc: Theodore Ts'o <tytso@....edu>
>> >> Cc: Andreas Dilger <adilger@....com>
>> >> Cc: Dave Kleikamp <shaggy@...ux.vnet.ibm.com>
>> >> Signed-off-by: Jing Zhang <zj.barak@...il.com>
>> >>
>> >> ---
>> >>
>> >> --- linux-2.6.32/fs/ext4/mballoc.c 2009-12-03 11:51:22.000000000 +0800
>> >> +++ ext4_mm_leak/mballoc3.c 2010-03-21 21:37:18.000000000 +0800
>> >> @@ -2360,6 +2360,24 @@ err_freesgi:
>> >> return -ENOMEM;
>> >> }
>> >>
>> >> +static void ext4_mb_destroy_backend(struct super_block *sb)
>> >> +{
>> >> + ext4_group_t ngroups = ext4_get_groups_count(sb);
>> >> + ext4_group_t i;
>> >> + struct ext4_sb_info *sbi = EXT4_SB(sb);
>> >> + int j;
>> >> + int num_meta_group_infos = (ngroups + EXT4_DESC_PER_BLOCK(sb) -1)
>> >> + >> EXT4_DESC_PER_BLOCK_BITS(sb);
>> >> + for (i = 0; i < ngroups; i++)
>> >> + kfree(ext4_get_group_info(sb, i));
>> >> +
>> >> + for (j = 0; j < num_meta_group_infos; j++)
>> >> + kfree(sbi->s_group_info[j]);
>> >> +
>> >> + kfree(sbi->s_group_info);
>> >> + iput(sbi->s_buddy_cache);
>> >> +}
>> >> +
>> >
>> > It would be better if this could be done by making ext4_mb_release()
>> > more flexible, and then calling ext4_mb_release() if there is an error
>> > setting up the data structures in ext4_mb_init().
>> >
>> > - Ted
>> >
>>
>> Yeah, Ted, going through ext4_mb_release() is clearer.
>>
>> ---
>>
>> diff --git a/linux-2.6.32/fs/ext4/mballoc.c b/ext4_mm_leak/mballoc3.c
>> index bba1282..99ca2de 100644
>> --- a/linux-2.6.32/fs/ext4/mballoc.c
>> +++ b/ext4_mm_leak/mballoc3.c
>> @@ -2417,8 +2417,7 @@ int ext4_mb_init(struct super_block *sb, int
>> needs_recovery)
>>
>> sbi->s_locality_groups = alloc_percpu(struct ext4_locality_group);
>> if (sbi->s_locality_groups == NULL) {
>> - kfree(sbi->s_mb_offsets);
>> - kfree(sbi->s_mb_maxs);
>> + ext4_mb_release(sb);
>
> We may want to make sure that we can safely call ext4_mb_release that
> early. what i would suggest is to move s_locality_group allocation
> before ext4_mb_init. that makes error handling easy
>
cool idea, Aneesh, and I got it.
---
--- old-linux-2.6.32/fs/ext4/mballoc.c 2009-12-03 11:51:22.000000000 +0800
+++ ext4_mm_leak/mballoc3-2.c 2010-03-28 16:13:20.000000000 +0800
@@ -2397,11 +2397,27 @@ int ext4_mb_init(struct super_block *sb,
i++;
} while (i <= sb->s_blocksize_bits + 1);
+ sbi->s_locality_groups = alloc_percpu(struct ext4_locality_group);
+ if (sbi->s_locality_groups == NULL) {
+ kfree(sbi->s_mb_offsets);
+ kfree(sbi->s_mb_maxs);
+ return -ENOMEM;
+ }
+ for_each_possible_cpu(i) {
+ struct ext4_locality_group *lg;
+ lg = per_cpu_ptr(sbi->s_locality_groups, i);
+ mutex_init(&lg->lg_mutex);
+ for (j = 0; j < PREALLOC_TB_SIZE; j++)
+ INIT_LIST_HEAD(&lg->lg_prealloc_list[j]);
+ spin_lock_init(&lg->lg_prealloc_lock);
+ }
+
/* init file for buddy data */
ret = ext4_mb_init_backend(sb);
if (ret != 0) {
kfree(sbi->s_mb_offsets);
kfree(sbi->s_mb_maxs);
+ free_percpu(sbi->s_locality_groups);
return ret;
}
@@ -2415,20 +2431,6 @@ int ext4_mb_init(struct super_block *sb,
sbi->s_mb_order2_reqs = MB_DEFAULT_ORDER2_REQS;
sbi->s_mb_group_prealloc = MB_DEFAULT_GROUP_PREALLOC;
- sbi->s_locality_groups = alloc_percpu(struct ext4_locality_group);
- if (sbi->s_locality_groups == NULL) {
- kfree(sbi->s_mb_offsets);
- kfree(sbi->s_mb_maxs);
- return -ENOMEM;
- }
- for_each_possible_cpu(i) {
- struct ext4_locality_group *lg;
- lg = per_cpu_ptr(sbi->s_locality_groups, i);
- mutex_init(&lg->lg_mutex);
- for (j = 0; j < PREALLOC_TB_SIZE; j++)
- INIT_LIST_HEAD(&lg->lg_prealloc_list[j]);
- spin_lock_init(&lg->lg_prealloc_lock);
- }
if (sbi->s_proc)
proc_create_data("mb_groups", S_IRUGO, sbi->s_proc,
>
>
>> return -ENOMEM;
>> }
>> for_each_possible_cpu(i) {
>> @@ -2511,7 +2510,8 @@ int ext4_mb_release(struct super_block *sb)
>> atomic_read(&sbi->s_mb_discarded));
>> }
>>
>> - free_percpu(sbi->s_locality_groups);
>> + if (sbi->s_locality_groups)
>> + free_percpu(sbi->s_locality_groups);
>> if (sbi->s_proc)
>> remove_proc_entry("mb_groups", sbi->s_proc);
>> --
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>
> -aneesh
>
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