[patch 008/100] ext4: fix locking typo in mballoc which could cause soft lockup hangs

Chris Wright
2009-04-23T07:31:41Z

[-- Attachment #1: ext4-fix-locking-typo-in-mballoc-which-could-cause-soft-lockup-hangs.patch --]
[-- Type: text/plain, Size: 1397 bytes --]

-stable review patch. If anyone has any objections, please let us know.
---------------------

From: Theodore Ts'o <tytso@mit.edu>

upstream commit: e7c9e3e99adf6c49c5d593a51375916acc039d1e

Smatch (http://repo.or.cz/w/smatch.git/) complains about the locking in
ext4_mb_add_n_trim() from fs/ext4/mballoc.c

4438 list_for_each_entry_rcu(tmp_pa, &lg->lg_prealloc_list[order],
4439 pa_inode_list) {
4440 spin_lock(&tmp_pa->pa_lock);
4441 if (tmp_pa->pa_deleted) {
4442 spin_unlock(&pa->pa_lock);
4443 continue;
4444 }

Brown paper bag time...

Reported-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
fs/ext4/mballoc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4439,7 +4439,7 @@ static void ext4_mb_add_n_trim(struct ex
pa_inode_list) {
spin_lock(&tmp_pa->pa_lock);
if (tmp_pa->pa_deleted) {
- spin_unlock(&pa->pa_lock);
+ spin_unlock(&tmp_pa->pa_lock);
continue;
}
if (!added && pa->pa_free < tmp_pa->pa_free) {