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From:   Yu Zhao <yuzhao@google.com>
Date:   Wed, 18 Oct 2023 10:21:47 -0600
Message-ID: <CAOUHufbPiAhpvHuo=oH7Zhyoc0hR-6kpVrCEe-b0OuWYWne2=A@mail.gmail.com>
Subject: Re: [PATCH 2/2] mm: multi-gen lru: fix stat count
To:     Huan Yang <link@vivo.com>
Cc:     Steven Rostedt <rostedt@goodmis.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Suren Baghdasaryan <surenb@google.com>,
        Vlastimil Babka <vbabka@suse.cz>, linux-kernel@vger.kernel.org,
        linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org,
        bpf@vger.kernel.org, opensource.kernel@vivo.com
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On Wed, Oct 18, 2023 at 2:22=E2=80=AFAM Huan Yang <link@vivo.com> wrote:
>
> For multi-gen lru reclaim in evict_folios, like shrink_inactive_list,
> gather folios which isolate to reclaim, and invoke shirnk_folio_list.
>
> But, when complete shrink, it not gather shrink reclaim stat into sc,
> we can't get info like nr_dirty\congested in reclaim, and then
> control writeback, dirty number and mark as LRUVEC_CONGESTED, or
> just bpf trace shrink and get correct sc stat.
>
> This patch fix this by simple copy code from shrink_inactive_list when
> end of shrink list.

MGLRU doesn't try to write back dirt file pages in the reclaim path --
it filters them out in sort_folio() and leaves them to the page
writeback. (The page writeback is a dedicated component for this
purpose). So there is nothing to fix.