linux-kernel - Re: [External] Re: [RFC PATCH 1/3] zram: charge the compressed RAM to the page's memcgroup

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Message-ID: <CACSyD1OFOz8F+2+mUxqLAMXx1p_Zv88iqrrDMd4kb9nYWE_FJA@mail.gmail.com>
Date:   Thu, 15 Jun 2023 17:41:51 +0800
From:   贺中坤 <hezhongkun.hzk@...edance.com>
To:     Yu Zhao <yuzhao@...gle.com>
Cc:     minchan@...nel.org, senozhatsky@...omium.org, mhocko@...e.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Fabian Deutsch <fdeutsch@...hat.com>
Subject: Re: [External] Re: [RFC PATCH 1/3] zram: charge the compressed RAM to
 the page's memcgroup

On Thu, Jun 15, 2023 at 1:00 PM Yu Zhao <yuzhao@...gle.com> wrote:
>
> On Wed, Jun 14, 2023 at 9:48 PM Zhongkun He
> <hezhongkun.hzk@...edance.com> wrote:
> >
> > The compressed RAM is currently charged to kernel, not to
> > any memory cgroup, which is not satisfy our usage scenario.
> > if the memory of a task is limited by memcgroup, it will
> > swap out the memory to zram swap device when the memory
> > is insufficient. In that case, the memory limit will have
> > no effect.
> >
> > So, it should makes sense to charge the compressed RAM to
> > the page's memory cgroup.
>
> We used to do this a long time ago, but we had per-memcg swapfiles [1[
> to prevent compressed pages from different memcgs from sharing the
> same zspage.
>
> Does this patchset alone suffer from the same problem, i.e., memcgs
> sharing zspages?
>
> [1] https://lwn.net/Articles/592923/

Thanks for your reply. Yes, different memcgs may share the same zspages.