[PATCH] Fix get_request nastiness

get_request is now expected to be holding on to queue_lock, with interrupts
disabled, when it returns NULL; but one path forgot that, causing all kinds
of nastiness under swap load - badness backtraces, strange failures, BUGs.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 3 deletions

diff --git a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
index 1197462bb6ba..692a5fced76e 100644
--- a/drivers/block/ll_rw_blk.c
+++ b/drivers/block/ll_rw_blk.c
@@ -1917,10 +1917,9 @@ get_rq:
          * limit of requests, otherwise we could have thousands of requests
          * allocated with any setting of ->nr_requests
          */
-        if (rl->count[rw] >= (3 * q->nr_requests / 2)) {
-                spin_unlock_irq(q->queue_lock);
+        if (rl->count[rw] >= (3 * q->nr_requests / 2))
                 goto out;
-        }
+
         rl->count[rw]++;
         rl->starved[rw] = 0;
         if (rl->count[rw] >= queue_congestion_on_threshold(q))