[merged mm-stable] memcg-do-not-modify-rstat-tree-for-zero-updates.patch removed from -mm tree

[merged mm-stable] memcg-do-not-modify-rstat-tree-for-zero-updates.patch removed from -mm tree

[Andrew Morton]

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The quilt patch titled
     Subject: memcg: do not modify rstat tree for zero updates
has been removed from the -mm tree.  Its filename was
     memcg-do-not-modify-rstat-tree-for-zero-updates.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Yosry Ahmed <yosryahmed@google.com>
Subject: memcg: do not modify rstat tree for zero updates
Date: Thu, 30 Mar 2023 19:18:01 +0000

In some situations, we may end up calling memcg_rstat_updated() with a
value of 0, which means the stat was not actually updated.  An example is
if we fail to reclaim any pages in shrink_folio_list().

Do not add the cgroup to the rstat updated tree in this case, to avoid
unnecessarily flushing it.

Link: https://lkml.kernel.org/r/20230330191801.1967435-9-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>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Michal Hocko <mhocko@kernel.org>
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>
---

 mm/memcontrol.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/mm/memcontrol.c~memcg-do-not-modify-rstat-tree-for-zero-updates
+++ a/mm/memcontrol.c
@@ -619,6 +619,9 @@ static inline void memcg_rstat_updated(s
 {
 	unsigned int x;
 
+	if (!val)
+		return;
+
 	cgroup_rstat_updated(memcg->css.cgroup, smp_processor_id());
 
 	x = __this_cpu_add_return(stats_updates, abs(val));
_

Patches currently in -mm which might be from yosryahmed@google.com are

memcg-page_cgroup_ino-get-memcg-from-the-pages-folio.patch
mm-vmscan-ignore-non-lru-based-reclaim-in-memcg-reclaim.patch
mm-vmscan-move-set_task_reclaim_state-near-flush_reclaim_state.patch
mm-vmscan-refactor-updating-current-reclaim_state.patch