This is a note to let you know that I've just added the patch titled
ext4: remove mb_groups before tearing down the buddy_cache
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-remove-mb_groups-before-tearing-down-the-buddy_cache.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From 95599968d19db175829fb580baa6b68939b320fb Mon Sep 17 00:00:00 2001
From: Salman Qazi <sq...@google.com>
Date: Thu, 31 May 2012 23:52:14 -0400
Subject: ext4: remove mb_groups before tearing down the buddy_cache
From: Salman Qazi <sq...@google.com>
commit 95599968d19db175829fb580baa6b68939b320fb upstream.
We can't have references held on pages in the s_buddy_cache while we are
trying to truncate its pages and put the inode. All the pages must be
gone before we reach clear_inode. This can only be gauranteed if we
can prevent new users from grabbing references to s_buddy_cache's pages.
The original bug can be reproduced and the bug fix can be verified by:
while true; do mount -t ext4 /dev/ram0 /export/hda3/ram0; \
umount /export/hda3/ram0; done &
while true; do cat /proc/fs/ext4/ram0/mb_groups; done
Signed-off-by: Salman Qazi <sq...@google.com>
Signed-off-by: "Theodore Ts'o" <ty...@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
fs/ext4/mballoc.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2517,6 +2517,9 @@ int ext4_mb_release(struct super_block *
struct ext4_sb_info *sbi = EXT4_SB(sb);
struct kmem_cache *cachep = get_groupinfo_cache(sb->s_blocksize_bits);
+ if (sbi->s_proc)
+ remove_proc_entry("mb_groups", sbi->s_proc);
+
if (sbi->s_group_info) {
for (i = 0; i < ngroups; i++) {
grinfo = ext4_get_group_info(sb, i);
@@ -2564,8 +2567,6 @@ int ext4_mb_release(struct super_block *
}
free_percpu(sbi->s_locality_groups);
- if (sbi->s_proc)
- remove_proc_entry("mb_groups", sbi->s_proc);
return 0;
}
Patches currently in stable-queue which might be from sq...@google.com are
queue-3.4/ext4-add-ext4_mb_unload_buddy-in-the-error-path.patch
queue-3.4/ext4-remove-mb_groups-before-tearing-down-the-buddy_cache.patch
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