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Date:   Fri, 6 Aug 2021 12:15:01 +0200
From:   Michal Hocko <mhocko@suse.com>
To:     Shakeel Butt <shakeelb@google.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>
Subject: Re: [PATCH v7 1/2] mm: introduce process_mrelease system call
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On Fri 06-08-21 02:23:17, Shakeel Butt wrote:
> On Thu, Aug 5, 2021 at 11:40 PM Michal Hocko <mhocko@suse.com> wrote:
> >
> [...]
> > I think you really want something like this:
> >
> >         if (flags)
> >                 return -EINVAL;
> >
> >         pid = pidfd_get_pid(fd, &f_flags);
> >         if (IS_ERR(pid))
> >                 return PTR_ERR(pid);
> >         task = get_pid_task(pid, PIDTYPE_PID);
> >         if (!task) {
> >                 ret = -ESRCH;
> >                 goto put_pid;
> >         }
> >
> >         /*
> >          * Make sure to chose a thread which still has a reference to mm
> >          * during the group exit
> >          */
> >         p = find_lock_task_mm(task);
> >         if (!p) {
> >                 ret = -ESRCH;
> >                 goto put_task;
> >         }
> >
> >         mm = task->mm;
> 
> mm = p->mm;

right. Thanks!

-- 
Michal Hocko
SUSE Labs