[PATCH] ext4: Memory leak fix ext4_group_info allocation.

[PATCH] ext4: Memory leak fix ext4_group_info allocation.

[Aneesh Kumar K.V]

commit 5f21b0e642d7bf6fe4434c9ba12bc9cb96b17cf7  was done to
reallocate groupinfo struct during resize properly. That goal
was to allocate new groupinfo struct when we are adding new block
groups during resize. Calling ext4_mb_add_group_info in the
mballoc initialization code path resulted in we reallocating
the group info struct . Fix this by not separately allocating
group info in the mballoc init path and always depend on
ext4_mb_add_group_info to allocate group info struct.

The earlier code also had a bug that we allocated less number of
group info struct for the last meta group. But on resize we
expected that we had EXT4_DESC_PER_BLOCK group info struct for
each meta group.

Reported-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
---
 fs/ext4/mballoc.c |   19 -------------------
 1 files changed, 0 insertions(+), 19 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 519a0a6..2a9d327 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2564,13 +2564,11 @@ static int ext4_mb_init_backend(struct super_block *sb)
 {
 	ext4_group_t ngroups = ext4_get_groups_count(sb);
 	ext4_group_t i;
-	int metalen;
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	struct ext4_super_block *es = sbi->s_es;
 	int num_meta_group_infos;
 	int num_meta_group_infos_max;
 	int array_size;
-	struct ext4_group_info **meta_group_info;
 	struct ext4_group_desc *desc;
 
 	/* This is the number of blocks used by GDT */
@@ -2615,22 +2613,6 @@ static int ext4_mb_init_backend(struct super_block *sb)
 		goto err_freesgi;
 	}
 	EXT4_I(sbi->s_buddy_cache)->i_disksize = 0;
-
-	metalen = sizeof(*meta_group_info) << EXT4_DESC_PER_BLOCK_BITS(sb);
-	for (i = 0; i < num_meta_group_infos; i++) {
-		if ((i + 1) == num_meta_group_infos)
-			metalen = sizeof(*meta_group_info) *
-				(ngroups -
-					(i << EXT4_DESC_PER_BLOCK_BITS(sb)));
-		meta_group_info = kmalloc(metalen, GFP_KERNEL);
-		if (meta_group_info == NULL) {
-			printk(KERN_ERR "EXT4-fs: can't allocate mem for a "
-			       "buddy group\n");
-			goto err_freemeta;
-		}
-		sbi->s_group_info[i] = meta_group_info;
-	}

Re: [PATCH] ext4: Memory leak fix ext4_group_info allocation.

[Theodore Tso]

On Wed, Jul 15, 2009 at 08:25:34PM +0530, Aneesh Kumar K.V wrote:
> commit 5f21b0e642d7bf6fe4434c9ba12bc9cb96b17cf7  was done to
> reallocate groupinfo struct during resize properly. That goal
> was to allocate new groupinfo struct when we are adding new block
> groups during resize. Calling ext4_mb_add_group_info in the
> mballoc initialization code path resulted in we reallocating
> the group info struct . Fix this by not separately allocating
> group info in the mballoc init path and always depend on
> ext4_mb_add_group_info to allocate group info struct.
> 
> The earlier code also had a bug that we allocated less number of
> group info struct for the last meta group. But on resize we
> expected that we had EXT4_DESC_PER_BLOCK group info struct for
> each meta group.

Added to the ext4 patch queue, although I did rewrite the patch
description:

ext4: Fix memory leak fix when mounting an ext4 filesystem

From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>

The allocation of the ext4_group_info array was moved to a new
function ext4_mb_add_group_info() in commit 5f21b0e6 so that online
resize would use a common (and correct) codepath.  Unfortunately, the
call to the new ext4_mb_add_group_info() function was added without
removing the code which originally allocated the array.  This caused a
memory leak each time an ext4 filesystem was mounted.

The fix is simple; remove the code that did the original allocation,
since it is no longer needed.

Reported-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

					- Ted