linux-kernel - Re: [PATCH v3 1/2] mm: introduce process

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Date:   Fri, 23 Jul 2021 06:40:53 -0700
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Michal Hocko <mhocko@...e.com>
Cc:     Suren Baghdasaryan <surenb@...gle.com>,
        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>,
        Minchan Kim <minchan@...nel.org>,
        Christian Brauner <christian@...uner.io>,
        Christoph Hellwig <hch@...radead.org>,
        Oleg Nesterov <oleg@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        Jann Horn <jannh@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Florian Weimer <fweimer@...hat.com>,
        Jan Engelhardt <jengelh@...i.de>,
        Tim Murray <timmurray@...gle.com>,
        Linux API <linux-api@...r.kernel.org>,
        Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-team <kernel-team@...roid.com>
Subject: Re: [PATCH v3 1/2] mm: introduce process_mrelease system call

On Thu, Jul 22, 2021 at 11:20 PM Michal Hocko <mhocko@...e.com> wrote:
>
> On Thu 22-07-21 21:47:56, Suren Baghdasaryan wrote:
> > On Thu, Jul 22, 2021, 7:04 PM Shakeel Butt <shakeelb@...gle.com> wrote:
> >
> > > On Thu, Jul 22, 2021 at 6:14 PM Suren Baghdasaryan <surenb@...gle.com>
> > > wrote:
> > > >
> > > [...]
> > > > +
> > > > +       mmap_read_lock(mm);
> > >
> > > How about mmap_read_trylock(mm) and return -EAGAIN on failure?
> > >
> >
> > That sounds like a good idea. Thanks! I'll add that in the next respin.
>
> Why is that a good idea? Can you do anything meaningful about the
> failure other than immediately retry the syscall and hope for the best?
>

Yes we can. Based on the situation/impact we can select more victims.