From: Kent Overstreet <kmo@daterainc.com>
Date: Tue, 24 Sep 2013 06:17:34 +0000 (-0700)
Subject: bcache: Fix a shrinker deadlock
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=a698e08c82dfb9771e0bac12c7337c706d729b6d;p=openwrt%2Fstaging%2Fblogic.git

bcache: Fix a shrinker deadlock

GFP_NOIO means we could be getting called recursively - mca_alloc() ->
mca_data_alloc() - definitely can't use mutex_lock(bucket_lock) then.
Whoops.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: linux-stable <stable@vger.kernel.org> # >= v3.10
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 8fad8402fb2e..f42fc7ed9cd6 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -612,7 +612,7 @@ static unsigned long bch_mca_scan(struct shrinker *shrink,
 		return SHRINK_STOP;
 
 	/* Return -1 if we can't do anything right now */
-	if (sc->gfp_mask & __GFP_WAIT)
+	if (sc->gfp_mask & __GFP_IO)
 		mutex_lock(&c->bucket_lock);
 	else if (!mutex_trylock(&c->bucket_lock))
 		return -1;