commit a698e08c 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@daterainc.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>