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From:   Suren Baghdasaryan <surenb@google.com>
Date:   Tue, 24 Nov 2020 08:42:28 -0800
Message-ID: <CAJuCfpGdH0EzA9KjNBtKm-yywx4XbvpXXBskQ-pzExXYsTqTRg@mail.gmail.com>
Subject: Re: [PATCH 2/2] mm/madvise: add process_madvise MADV_DONTNEER support
To:     Oleg Nesterov <oleg@redhat.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@kernel.org>,
        Michal Hocko <mhocko@suse.com>,
        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>,
        Tim Murray <timmurray@google.com>, 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 Tue, Nov 24, 2020 at 5:42 AM Oleg Nesterov <oleg@redhat.com> wrote:
>
> On 11/23, Suren Baghdasaryan wrote:
> >
> > +     if (madvise_destructive(behavior)) {
> > +             /* Allow destructive madvise only on a dying processes */
> > +             if (!signal_group_exit(task->signal)) {
>
> signal_group_exit(task) is true if this task execs and kills other threads,
> see the comment above this helper.
>
> I think you need !(task->signal->flags & SIGNAL_GROUP_EXIT).

I see. Thanks for the feedback, Oleg. I'll test and fix it in the next version.

>
> Oleg.
>