2013-01-11 10:06:44

by Mel Gorman

[permalink] [raw]
Subject: [PATCH] ext4: Fix memory leak in ext4_init_new_dir

Commit a774f9c2 "ext4: make ext4_init_dot_dotdot for inline dir usage"
is a preparation cleanup for later ext4 patches but there was a snag
when moving code to the newly created ext4_init_new_dir() function.
ext4_bread() is called twice but brelse() is only called one leading to a
memory leak. The user-visible effect is that after a compile-orientated
benchmark 0% of memory could be allocated as transparent huge pages.
This patch deletes the extra call and after it is applied, 76% of memory
could be allocated after the same test.

Signed-off-by: Mel Gorman <[email protected]>
---
fs/ext4/namei.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 8990165..d068885 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2368,7 +2368,6 @@ static int ext4_init_new_dir(handle_t *handle, struct inode *dir,
}

inode->i_size = EXT4_I(inode)->i_disksize = blocksize;
- dir_block = ext4_bread(handle, inode, 0, 1, &err);
if (!(dir_block = ext4_bread(handle, inode, 0, 1, &err))) {
if (!err) {
err = -EIO;


2013-01-11 10:12:35

by Tao Ma

[permalink] [raw]
Subject: Re: [PATCH] ext4: Fix memory leak in ext4_init_new_dir

Hi Mel,

Thanks for the report.

This bug is already spotted by Guo Chao and the patch has been accepted
by Ted already.

Thanks,
Tao
On 01/11/2013 06:06 PM, Mel Gorman wrote:
> Commit a774f9c2 "ext4: make ext4_init_dot_dotdot for inline dir usage"
> is a preparation cleanup for later ext4 patches but there was a snag
> when moving code to the newly created ext4_init_new_dir() function.
> ext4_bread() is called twice but brelse() is only called one leading to a
> memory leak. The user-visible effect is that after a compile-orientated
> benchmark 0% of memory could be allocated as transparent huge pages.
> This patch deletes the extra call and after it is applied, 76% of memory
> could be allocated after the same test.
>
> Signed-off-by: Mel Gorman <[email protected]>
> ---
> fs/ext4/namei.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> index 8990165..d068885 100644
> --- a/fs/ext4/namei.c
> +++ b/fs/ext4/namei.c
> @@ -2368,7 +2368,6 @@ static int ext4_init_new_dir(handle_t *handle, struct inode *dir,
> }
>
> inode->i_size = EXT4_I(inode)->i_disksize = blocksize;
> - dir_block = ext4_bread(handle, inode, 0, 1, &err);
> if (!(dir_block = ext4_bread(handle, inode, 0, 1, &err))) {
> if (!err) {
> err = -EIO;
> --
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>


2013-01-11 10:30:45

by Mel Gorman

[permalink] [raw]
Subject: Re: [PATCH] ext4: Fix memory leak in ext4_init_new_dir

On Fri, Jan 11, 2013 at 06:12:17PM +0800, Tao Ma wrote:
> Hi Mel,
>
> Thanks for the report.
>
> This bug is already spotted by Guo Chao and the patch has been accepted
> by Ted already.
>

Ah grand, I see now that it was merged for 3.8-rc3. Thanks for the heads up.

--
Mel Gorman
SUSE Labs