linux-kernel - Re: [PATCH 1/2] mm/madvise: allow process_madvise operations on entire memory range

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Date:   Wed, 23 Dec 2020 08:57:12 +0100
From:   Christoph Hellwig <hch@....de>
To:     Suren Baghdasaryan <surenb@...gle.com>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Jann Horn <jannh@...gle.com>, Minchan Kim <minchan@...nel.org>,
        Christoph Hellwig <hch@....de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>,
        Michal Hocko <mhocko@...e.com>,
        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>,
        Linux API <linux-api@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>,
        kernel list <linux-kernel@...r.kernel.org>,
        kernel-team <kernel-team@...roid.com>
Subject: Re: [PATCH 1/2] mm/madvise: allow process_madvise operations on
 entire memory range

On Tue, Dec 22, 2020 at 09:48:43AM -0800, Suren Baghdasaryan wrote:
> Thanks for the feedback! The use case is userspace memory reaping
> similar to oom-reaper. Detailed justification is here:
> https://lore.kernel.org/linux-mm/20201124053943.1684874-1-surenb@google.com

Given that this new variant of process_madvise

  a) does not work on an address range
  b) is destructive
  c) doesn't share much code at all with the rest of process_madvise

Why not add a proper separate syscall?