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Date:   Tue, 17 Mar 2020 16:58:55 +0100
From:   Michal Hocko <mhocko@kernel.org>
To:     Minchan Kim <minchan@kernel.org>
Cc:     Jann Horn <jannh@google.com>, Linux-MM <linux-mm@kvack.org>,
        kernel list <linux-kernel@vger.kernel.org>,
        Daniel Colascione <dancol@google.com>,
        Dave Hansen <dave.hansen@intel.com>,
        "Joel Fernandes (Google)" <joel@joelfernandes.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: interaction of MADV_PAGEOUT with CoW anonymous mappings?
Message-ID: <20200317155855.GS26018@dhcp22.suse.cz>
References: <20200312082248.GS23944@dhcp22.suse.cz>
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 <20200313020851.GD68817@google.com>
 <20200313080546.GA21007@dhcp22.suse.cz>
 <20200313205941.GA78185@google.com>
 <20200316092052.GD11482@dhcp22.suse.cz>
 <20200317014340.GA73302@google.com>
 <20200317071239.GB26018@dhcp22.suse.cz>
 <20200317150055.GC73302@google.com>
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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