linux-kernel - Re: [PATCH] mm: filemap: clear idle flag for writes

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Date:   Wed, 24 Jun 2020 12:49:52 -0700
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Yang Shi <yang.shi@...ux.alibaba.com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Rik van Riel <riel@...riel.com>, gavin.dg@...ux.alibaba.com,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: filemap: clear idle flag for writes

On Wed, Jun 24, 2020 at 10:43 AM Yang Shi <yang.shi@...ux.alibaba.com> wrote:
>
> Since commit bbddabe2e436aa7869b3ac5248df5c14ddde0cbf ("mm: filemap:
> only do access activations on reads"), mark_page_accessed() is called
> for reads only.  But the idle flag is cleared by mark_page_accessed() so
> the idle flag won't get cleared if the page is write accessed only.
>
> Basically idle page tracking is used to estimate workingset size of
> workload, noticeable size of workingset might be missed if the idle flag
> is not maintained correctly.
>
> It seems good enough to just clear idle flag for write operations.
>
> Fixes: bbddabe2e436 ("mm: filemap: only do access activations on reads")
> Cc: Johannes Weiner <hannes@...xchg.org>
> Cc: Rik van Riel <riel@...riel.com>
> Cc: Shakeel Butt <shakeelb@...gle.com>
> Reported-by: Gang Deng <gavin.dg@...ux.alibaba.com>
> Signed-off-by: Yang Shi <yang.shi@...ux.alibaba.com>

Reviewed-by: Shakeel Butt <shakeelb@...gle.com>