linux-kernel - Re: [RFC]: userspace memory reaping

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Message-ID: <20201104065844.GM21990@dhcp22.suse.cz>
Date:   Wed, 4 Nov 2020 07:58:44 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     Minchan Kim <minchan@...nel.org>
Cc:     Suren Baghdasaryan <surenb@...gle.com>, linux-api@...r.kernel.org,
        linux-mm <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Rientjes <rientjes@...gle.com>,
        Matthew Wilcox <willy@...radead.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Roman Gushchin <guro@...com>, Rik van Riel <riel@...riel.com>,
        Christian Brauner <christian@...uner.io>,
        Oleg Nesterov <oleg@...hat.com>,
        Tim Murray <timmurray@...gle.com>,
        kernel-team <kernel-team@...roid.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Mel Gorman <mgorman@...hsingularity.net>
Subject: Re: [RFC]: userspace memory reaping

On Tue 03-11-20 13:32:28, Minchan Kim wrote:
> On Tue, Nov 03, 2020 at 10:35:50AM +0100, Michal Hocko wrote:
> > On Mon 02-11-20 12:29:24, Suren Baghdasaryan wrote:
> > [...]
> > > To follow up on this. Should I post an RFC implementing SIGKILL_SYNC
> > > which in addition to sending a kill signal would also reap the
> > > victim's mm in the context of the caller? Maybe having some code will
> > > get the discussion moving forward?
> > 
> > Yeah, having a code, even preliminary, might help here. This definitely
> > needs a good to go from process management people as that proper is land
> > full of surprises...
> 
> Just to remind a idea I suggested to reuse existing concept
> 
>     fd = pidfd_open(victim process)
>     fdatasync(fd);
>     close(fd);

I must have missed this proposal. Anyway, are you suggesting fdatasync
to act as a destructive operation?

-- 
Michal Hocko
SUSE Labs