[patch 53/60] ext4: fix locking typo in mballoc which could cause soft lockup hangs

[Greg KH]

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

------------------
From: "Theodore Ts'o" <tytso@xxxxxxx>

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@xxxxxxxxx>
Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxx>
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
Cc: stable@xxxxxxxxxx
Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 fs/ext4/mballoc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4532,7 +4532,7 @@ 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) {


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