+ mm-memcg-bypass-high-reclaim-iteration-for-cgroup-hierarchy-root.patch added to -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm, memcg: bypass high reclaim iteration for cgroup hierarchy root
has been added to the -mm tree.  Its filename is
     mm-memcg-bypass-high-reclaim-iteration-for-cgroup-hierarchy-root.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-bypass-high-reclaim-iteration-for-cgroup-hierarchy-root.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-memcg-bypass-high-reclaim-iteration-for-cgroup-hierarchy-root.patch

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------------------------------------------------------
From: Chris Down <chris@chrisdown.name>
Subject: mm, memcg: bypass high reclaim iteration for cgroup hierarchy root

The root of the hierarchy cannot have high set, so we will never reclaim
based on it.  This makes that clearer and avoids another entry.

Link: http://lkml.kernel.org/r/20200312164137.GA1753625@chrisdown.name
Signed-off-by: Chris Down <chris@chrisdown.name>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memcontrol.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/mm/memcontrol.c~mm-memcg-bypass-high-reclaim-iteration-for-cgroup-hierarchy-root
+++ a/mm/memcontrol.c
@@ -2246,7 +2246,8 @@ static void reclaim_high(struct mem_cgro
 			continue;
 		memcg_memory_event(memcg, MEMCG_HIGH);
 		try_to_free_mem_cgroup_pages(memcg, nr_pages, gfp_mask, true);
-	} while ((memcg = parent_mem_cgroup(memcg)));
+	} while ((memcg = parent_mem_cgroup(memcg)) &&
+		 !mem_cgroup_is_root(memcg));
 }
 
 static void high_work_func(struct work_struct *work)
_

Patches currently in -mm which might be from chris@chrisdown.name are

mm-memcg-fix-corruption-on-64-bit-divisor-in-memoryhigh-throttling.patch
mm-memcg-throttle-allocators-based-on-ancestral-memoryhigh.patch
mm-memcg-prevent-memoryhigh-load-store-tearing.patch
mm-memcg-prevent-memorymax-load-tearing.patch
mm-memcg-prevent-memorylow-load-store-tearing.patch
mm-memcg-prevent-memorymin-load-store-tearing.patch
mm-memcg-prevent-memoryswapmax-load-tearing.patch
mm-memcg-prevent-mem_cgroup_protected-store-tearing.patch
mm-memcg-bypass-high-reclaim-iteration-for-cgroup-hierarchy-root.patch