block,blkcg: use __GFP_NOWARN for best-effort allocations in blkcg

commit e00f4f4d0ff7e13b9115428a245b49108d625f09 upstream.

blkcg allocates some per-cgroup data structures with GFP_NOWAIT and
when that fails falls back to operations which aren't specific to the
cgroup.  Occassional failures are expected under pressure and falling
back to non-cgroup operation is the right thing to do.

Unfortunately, I forgot to add __GFP_NOWARN to these allocations and
these expected failures end up creating a lot of noise.  Add
__GFP_NOWARN.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Marc MERLIN <marc@merlins.org>
Reported-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index b2dc1c1..a4e2d01 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3868,7 +3868,8 @@ cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
 			goto out;
 	}
 
-	cfqq = kmem_cache_alloc_node(cfq_pool, GFP_NOWAIT | __GFP_ZERO,
+	cfqq = kmem_cache_alloc_node(cfq_pool,
+				     GFP_NOWAIT | __GFP_ZERO | __GFP_NOWARN,
 				     cfqd->queue->node);
 	if (!cfqq) {
 		cfqq = &cfqd->oom_cfqq;