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

Michal Hocko
2020-08-13T11:01:02Z

On Thu 13-08-20 17:45:19, Alex Shi wrote:
>
>
> 在 2020/8/13 下午2:20, Michal Hocko 写道:
> > On Wed 12-08-20 11:25:53, Alex Shi wrote:
> >> >From 999b0fe5fc65865c3b59ff28500d45572a4a9570 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] mm/memcg: bail out early from swap accounting when memcg
> >> is disabled
> >>
> >> If we disabled memcg by cgroup_disable=memory, page->memcg will be NULL
> >> and so the charge is skipped and that will trigger a warning like below.
> >> Let's return from the funcs earlier.
> >>
> >> ---[ end trace f1f34bfc3b32ed2f ]---
> >> anon flags:0x5005b48008000d(locked|uptodate|dirty|swapbacked)
> >> raw: 005005b48008000d dead000000000100 dead000000000122 ffff8897c7c76ad1
> >> raw: 0000000000000022 0000000000000000 0000000200000000 0000000000000000
> >> page dumped because: VM_WARN_ON_ONCE_PAGE(!memcg)
> >
> > Yes this is better. It would be even more informative if you added the
> > backtrace.
>
> The stack is a bit long.

This doesn't matter. It is informative and potentially useful for future
reference.

Thanks!
--
Michal Hocko
SUSE Labs