linux-kernel - Re: [RFC] prctl: Deprecate non PR_SET_MM

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Date:   Wed, 4 Apr 2018 07:35:41 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Yang Shi <yang.shi@...ux.alibaba.com>
Cc:     Cyrill Gorcunov <gorcunov@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrey Vagin <avagin@...nvz.org>,
        Andrew Morton <akpm@...uxfoundation.org>,
        Pavel Emelyanov <xemul@...tuozzo.com>,
        Michael Kerrisk <mtk.manpages@...il.com>
Subject: Re: [RFC] prctl: Deprecate non PR_SET_MM_MAP operations

On Tue 03-04-18 16:15:20, Yang Shi wrote:
> 
> 
> On 4/3/18 3:37 PM, Cyrill Gorcunov wrote:
> > An ability to manipulate mm_struct fields was introduced in
> > sake of CRIU in first place. Later we provide more suitable
> > and safe operation PR_SET_MM_MAP where all fields to be modifed
> > are passed in one structure which allows us to make more detailed
> > verification.
> > 
> > Still old interface remains present for compatibility reason
> > though CRIU itself already switched to PR_SET_MM_MAP on its
> > own long ago.
> > 
> > Googling didn't reveal some other users of this operation
> > so I think it should be safe to issue deprecation warning
> > first time and get rid of this interface after a couple
> > of releases.
> > 
> > CC: Andrey Vagin <avagin@...nvz.org>
> > CC: Andrew Morton <akpm@...uxfoundation.org>
> > CC: Pavel Emelyanov <xemul@...tuozzo.com>
> > CC: Michael Kerrisk <mtk.manpages@...il.com>
> > CC: Yang Shi <yang.shi@...ux.alibaba.com>
> > CC: Michal Hocko <mhocko@...nel.org>
> > Signed-off-by: Cyrill Gorcunov <gorcunov@...il.com>
> > ---
> > Or we can simply drop it off because PR_SET_MM_MAP covers all needs,
> > and I would rather prefer to do that asap.
> 
> Thanks for making it deprecated. I'd prefer just drop it off if nobody
> objects. The change will get soaked in linux-next for a while , we will know
> if it breaks compatibility (it sounds very unlikely).

Yeah, let's just drop it and have the patch in linux-next (via mmotm)
for 2 release cycles and see whether somebody complains.

You can add
Acked-by: Michal Hocko <mhocko@...e.com>
for such a patch.
-- 
Michal Hocko
SUSE Labs