linux-kernel - [PATCH 4.9 11/70] block,blkcg: use __GFP_NOWARN for best-effort allocations in blkcg

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Message-Id: <20180917211650.163730224@linuxfoundation.org>
Date:   Tue, 18 Sep 2018 00:41:44 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Tejun Heo <tj@...nel.org>,
        Marc MERLIN <marc@...lins.org>,
        Vlastimil Babka <vbabka@...e.cz>, Jens Axboe <axboe@...com>,
        Amit Pundir <amit.pundir@...aro.org>
Subject: [PATCH 4.9 11/70] block,blkcg: use __GFP_NOWARN for best-effort allocations in blkcg

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

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

From: Tejun Heo <tj@...nel.org>

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@...nel.org>
Reported-by: Marc MERLIN <marc@...lins.org>
Reported-by: Vlastimil Babka <vbabka@...e.cz>
Signed-off-by: Jens Axboe <axboe@...com>
Signed-off-by: Amit Pundir <amit.pundir@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 block/blk-cgroup.c  |    9 +++++----
 block/cfq-iosched.c |    3 ++-
 2 files changed, 7 insertions(+), 5 deletions(-)

--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -185,7 +185,8 @@ static struct blkcg_gq *blkg_create(stru
 	}
 
 	wb_congested = wb_congested_get_create(&q->backing_dev_info,
-					       blkcg->css.id, GFP_NOWAIT);
+					       blkcg->css.id,
+					       GFP_NOWAIT | __GFP_NOWARN);
 	if (!wb_congested) {
 		ret = -ENOMEM;
 		goto err_put_css;
@@ -193,7 +194,7 @@ static struct blkcg_gq *blkg_create(stru
 
 	/* allocate */
 	if (!new_blkg) {
-		new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT);
+		new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT | __GFP_NOWARN);
 		if (unlikely(!new_blkg)) {
 			ret = -ENOMEM;
 			goto err_put_congested;
@@ -1022,7 +1023,7 @@ blkcg_css_alloc(struct cgroup_subsys_sta
 	}
 
 	spin_lock_init(&blkcg->lock);
-	INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT);
+	INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT | __GFP_NOWARN);
 	INIT_HLIST_HEAD(&blkcg->blkg_list);
 #ifdef CONFIG_CGROUP_WRITEBACK
 	INIT_LIST_HEAD(&blkcg->cgwb_list);
@@ -1238,7 +1239,7 @@ pd_prealloc:
 		if (blkg->pd[pol->plid])
 			continue;
 
-		pd = pol->pd_alloc_fn(GFP_NOWAIT, q->node);
+		pd = pol->pd_alloc_fn(GFP_NOWAIT | __GFP_NOWARN, q->node);
 		if (!pd)
 			swap(pd, pd_prealloc);
 		if (!pd) {
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3868,7 +3868,8 @@ cfq_get_queue(struct cfq_data *cfqd, boo
 			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;