linux-kernel - [ 09/57] bcache: Fix a shrinker deadlock

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Date:	Wed,  2 Oct 2013 21:08:35 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Kent Overstreet <kmo@...erainc.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [ 09/57] bcache: Fix a shrinker deadlock

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

------------------

From: Kent Overstreet <kmo@...erainc.com>

commit a698e08c82dfb9771e0bac12c7337c706d729b6d upstream.

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@...erainc.com>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/md/bcache/btree.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -617,7 +617,7 @@ static int bch_mca_shrink(struct shrinke
 		return mca_can_free(c) * c->btree_pages;
 
 	/* 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;


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