linux-kernel - Re: [External] Re: [PATCH 4/4] mm: memcontrol: fix swap uncharge on cgroup v2

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Message-ID: <YCpL357b8GFRYo1T@dhcp22.suse.cz>
Date:   Mon, 15 Feb 2021 11:24:31 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     Muchun Song <songmuchun@...edance.com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Cgroups <cgroups@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [External] Re: [PATCH 4/4] mm: memcontrol: fix swap uncharge on
 cgroup v2

On Mon 15-02-21 18:15:36, Muchun Song wrote:
> On Mon, Feb 15, 2021 at 5:47 PM Michal Hocko <mhocko@...e.com> wrote:
> >
> > On Sat 13-02-21 01:01:59, Muchun Song wrote:
> > > The swap charges the actual number of swap entries on cgroup v2.
> > > If a swap cache page is charged successful, and then we uncharge
> > > the swap counter. It is wrong on cgroup v2. Because the swap
> > > entry is not freed.
> >
> > Is there any actual problem though? Can you describe the specific
> > scenario please? Swap cache charge life time is a bit tricky and I have
> > to confess I have to relearn it every time I need to understand it. The
> > patch would be much more easier to review if the changelog was much more
> > specific.
> 
> I copied the reply to Shakeel here. :-)

Not helpful much. I have seen that reply before answering your patch.
I really have to say I find it rather annoying to constantly get unclear
and cryptic responses from you. This is a subtle area! Make your claims
clear and specific so they can be verified.

-- 
Michal Hocko
SUSE Labs