vmscan: memcg: sleep when flushing stats during reclaim

Memory reclaim is a sleepable context.  Flushing is an expensive operaiton
that scales with the number of cpus and the number of cgroups in the
system, so avoid doing it atomically unnecessarily.  This can slow down
reclaim code if flushing stats is taking too long, but there is already
multiple cond_resched()'s in reclaim code.

Link: https://lkml.kernel.org/r/20230330191801.1967435-8-yosryahmed@google.com
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vasily Averin <vasily.averin@linux.dev>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index c68db50ec1092e26eea0033a9cbd84452169a52c..98719e72b5e2d48c1fc14b10af8ffd67f5f8a26e 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2861,7 +2861,7 @@ static void prepare_scan_count(pg_data_t *pgdat, struct scan_control *sc)
         * Flush the memory cgroup stats, so that we read accurate per-memcg
         * lruvec stats for heuristics.
         */
-       mem_cgroup_flush_stats_atomic();
+       mem_cgroup_flush_stats();
 
        /*
         * Determine the scan balance between anon and file LRUs.