linux-kernel - Re: interaction of MADV_PAGEOUT with CoW anonymous mappings?

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Message-ID: <20200317155855.GS26018@dhcp22.suse.cz>
Date:   Tue, 17 Mar 2020 16:58:55 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Minchan Kim <minchan@...nel.org>
Cc:     Jann Horn <jannh@...gle.com>, Linux-MM <linux-mm@...ck.org>,
        kernel list <linux-kernel@...r.kernel.org>,
        Daniel Colascione <dancol@...gle.com>,
        Dave Hansen <dave.hansen@...el.com>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: interaction of MADV_PAGEOUT with CoW anonymous mappings?

On Tue 17-03-20 08:00:55, Minchan Kim wrote:
> On Tue, Mar 17, 2020 at 08:12:39AM +0100, Michal Hocko wrote:
[...]
> > Just to make it clear, are you really suggesting to special case
> > page_check_references for madvise path?
> > 
> 
> No, (page_mapcount() >  1) checks *effectively* fixes the performance
> bug as well as vulnerability issue.

Ahh, ok then we are on the same page. You were replying to the part
where I have pointed out that you can control aging by these calls
and your response suggested that this is somehow undesirable behavior or
even a bug.

-- 
Michal Hocko
SUSE Labs