linux-kernel - [PATCH v5 2/5] memcg: flush stats non-atomically in mem_cgroup_wb

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Message-ID: <20230421174020.2994750-3-yosryahmed@google.com>
Date:   Fri, 21 Apr 2023 17:40:17 +0000
From:   Yosry Ahmed <yosryahmed@...gle.com>
To:     Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Shakeel Butt <shakeelb@...gle.com>,
        Muchun Song <songmuchun@...edance.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Tejun Heo <tj@...nel.org>
Cc:     Jan Kara <jack@...e.cz>, Jens Axboe <axboe@...nel.dk>,
        "Michal Koutný" <mkoutny@...e.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        cgroups@...r.kernel.org, linux-mm@...ck.org,
        Yosry Ahmed <yosryahmed@...gle.com>
Subject: [PATCH v5 2/5] memcg: flush stats non-atomically in mem_cgroup_wb_stats()

The previous patch moved the wb_over_bg_thresh()->mem_cgroup_wb_stats()
code path in wb_writeback() outside the lock section. We no longer need
to flush the stats atomically. Flush the stats non-atomically.

Signed-off-by: Yosry Ahmed <yosryahmed@...gle.com>
Reviewed-by: Michal Koutný <mkoutny@...e.com>
Acked-by: Shakeel Butt <shakeelb@...gle.com>
---
 mm/memcontrol.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4b27e245a055..5e79fdf8442b 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4648,11 +4648,7 @@ void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages,
 	struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css);
 	struct mem_cgroup *parent;
 
-	/*
-	 * wb_writeback() takes a spinlock and calls
-	 * wb_over_bg_thresh()->mem_cgroup_wb_stats(). Do not sleep.
-	 */
-	mem_cgroup_flush_stats_atomic();
+	mem_cgroup_flush_stats();
 
 	*pdirty = memcg_page_state(memcg, NR_FILE_DIRTY);
 	*pwriteback = memcg_page_state(memcg, NR_WRITEBACK);
-- 
2.40.0.634.g4ca3ef3211-goog