Re: [Resend PATCH 2/6] mm/memcg: remove useless check on page->mem_cgroup

Alex Shi
2020-08-11T12:54:18Z

From beeac61119ab39b1869c520c0f272fb8bab93765 Mon Sep 17 00:00:00 2001
From: Alex Shi <alex.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org>
Date: Wed, 5 Aug 2020 21:02:30 +0800
Subject: [PATCH 2/6] memcg: bail out early from swap accounting when memcg is
disabled

If we disabled memcg by cgroup_disable=memory, the swap charges are
still called. Let's return from the funcs earlier.

Signed-off-by: Alex Shi <alex.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org>
Reviewed-by: Roman Gushchin <guro-b10kYP2dOMg@public.gmane.org>
Acked-by: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>
Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
Cc: Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Vladimir Davydov <vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Cc: linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org
Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
---
mm/memcontrol.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 299382fc55a9..419cf565f40b 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -7098,6 +7098,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
VM_BUG_ON_PAGE(PageLRU(page), page);
VM_BUG_ON_PAGE(page_count(page), page);

+ if (mem_cgroup_disabled())
+ return;
+
if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
return;

@@ -7163,6 +7166,9 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry)
struct mem_cgroup *memcg;
unsigned short oldid;

+ if (mem_cgroup_disabled())
+ return 0;
+
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
return 0;

--
1.8.3.1