On Mon 10-08-20 11:52:02, Michal Hocko wrote:

On Wed 05-08-20 21:02:30, Alex Shi wrote:

quoted

在 2020/8/5 下午8:28, Alex Shi 写道:

quoted

The last patch has a problem on define. this version could fix it.

BTW, I see some !memcg happens when MEMCG compilered but disabled by cgroup_disable


[   94.657666] ---[ end trace f1f34bfc3b32ed2f ]---
[   95.138995] anon flags: 0x5005b48008000d(locked|uptodate|dirty|swapbacked)
[   95.146220] raw: 005005b48008000d dead000000000100 dead000000000122 ffff8897c7c76ad1
[   95.154549] raw: 0000000000000022 0000000000000000 0000000200000000 0000000000000000
[   95.162876] page dumped because: VM_WARN_ON_ONCE_PAGE(!memcg)

The following patch may helpful.

quoted

From 8bfb26a2e37e08dc61d20212bcfa5812a367ba94 Mon Sep 17 00:00:00 2001

From: Alex Shi <alex.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org>
Date: Wed, 5 Aug 2020 20:32:12 +0800
Subject: [PATCH] mm/memcg: don't try charge swap if memcg disabled

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

Do I get it right that this is on top of your patch to remove the memcg
check or a preparatory work?

Sorry meant to say - add the warning rather than drop the check.

Both are good but it would be better to
call that out specifically for clarity (along with the warning if that
is a follow up fix).

-- 
Michal Hocko
SUSE Labs