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From:   Shakeel Butt <shakeelb@google.com>
Date:   Fri, 23 Jul 2021 06:40:53 -0700
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Subject: Re: [PATCH v3 1/2] mm: introduce process_mrelease system call
To:     Michal Hocko <mhocko@suse.com>
Cc:     Suren Baghdasaryan <surenb@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Rientjes <rientjes@google.com>,
        Matthew Wilcox <willy@infradead.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Roman Gushchin <guro@fb.com>, Rik van Riel <riel@surriel.com>,
        Minchan Kim <minchan@kernel.org>,
        Christian Brauner <christian@brauner.io>,
        Christoph Hellwig <hch@infradead.org>,
        Oleg Nesterov <oleg@redhat.com>,
        David Hildenbrand <david@redhat.com>,
        Jann Horn <jannh@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        Florian Weimer <fweimer@redhat.com>,
        Jan Engelhardt <jengelh@inai.de>,
        Tim Murray <timmurray@google.com>,
        Linux API <linux-api@vger.kernel.org>,
        Linux MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        kernel-team <kernel-team@android.com>
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On Thu, Jul 22, 2021 at 11:20 PM Michal Hocko <mhocko@suse.com> wrote:
>
> On Thu 22-07-21 21:47:56, Suren Baghdasaryan wrote:
> > On Thu, Jul 22, 2021, 7:04 PM Shakeel Butt <shakeelb@google.com> wrote:
> >
> > > On Thu, Jul 22, 2021 at 6:14 PM Suren Baghdasaryan <surenb@google.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.