linux-kernel - [PATCH v7 06/10] mm: don't check the dying flag on kmem

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Message-ID: <20190611231813.3148843-7-guro@fb.com>
Date:   Tue, 11 Jun 2019 16:18:09 -0700
From:   Roman Gushchin <guro@...com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <kernel-team@...com>, Johannes Weiner <hannes@...xchg.org>,
        Shakeel Butt <shakeelb@...gle.com>,
        Waiman Long <longman@...hat.com>, Roman Gushchin <guro@...com>
Subject: [PATCH v7 06/10] mm: don't check the dying flag on kmem_cache creation

There is no point in checking the root_cache->memcg_params.dying
flag on kmem_cache creation path. New allocations shouldn't be
performed using a dead root kmem_cache, so no new memcg kmem_cache
creation can be scheduled after the flag is set. And if it was
scheduled before, flush_memcg_workqueue() will wait for it anyway.

So let's drop this check to simplify the code.

Signed-off-by: Roman Gushchin <guro@...com>
---
 mm/slab_common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 5e7638f495d1..9383104651cd 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -640,7 +640,7 @@ void memcg_create_kmem_cache(struct mem_cgroup *memcg,
 	 * The memory cgroup could have been offlined while the cache
 	 * creation work was pending.
 	 */
-	if (memcg->kmem_state != KMEM_ONLINE || root_cache->memcg_params.dying)
+	if (memcg->kmem_state != KMEM_ONLINE)
 		goto out_unlock;
 
 	idx = memcg_cache_id(memcg);
-- 
2.21.0