Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210623192822.3072029-1-surenb@google.com> <CALCETrU577MD59P-+9sMYtS3t2sZYx-zi=VirhQpZLnhEck1vg@mail.gmail.com>
 <CAJuCfpFMTP-g9CFELMqNawX0FhF4vBNtRDP_R=WAi_RiuGW8-Q@mail.gmail.com>
 <YNzl6XNu2vxyCJu8@cmpxchg.org> <CALCETrWsVw4+jT_Z1uxidRAZ0SQbngYe7E2m-8iyX6qRbug6zA@mail.gmail.com>
 <CAJuCfpG5Ua7C4usJGEqTm6_UUd6VyRd0BsPgT97LWOzjb4Ry+g@mail.gmail.com>
 <20210702152724.7fv5tnik4qlap6do@wittgenstein> <af8e76f1-6625-25d1-98d2-a3c8a9bf2fd6@redhat.com>
 <YOWcj0+P238W1y+t@dhcp22.suse.cz>
In-Reply-To: <YOWcj0+P238W1y+t@dhcp22.suse.cz>
From:   Suren Baghdasaryan <surenb@google.com>
Date:   Wed, 7 Jul 2021 14:14:23 -0700
Message-ID: <CAJuCfpH8QQyxivztkC2-_Kk1MqA0mJVs91XXpvVsL=NzNebshw@mail.gmail.com>
Subject: Re: [PATCH 1/1] mm: introduce process_reap system call
To:     Michal Hocko <mhocko@suse.com>
Cc:     David Hildenbrand <david@redhat.com>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        Andy Lutomirski <luto@kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        David Rientjes <rientjes@google.com>,
        Matthew Wilcox <willy@infradead.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>, Jann Horn <jannh@google.com>,
        Shakeel Butt <shakeelb@google.com>,
        Tim Murray <timmurray@google.com>,
        Linux API <linux-api@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Android Kernel Team <kernel-team@android.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Wed, Jul 7, 2021 at 5:38 AM Michal Hocko <mhocko@suse.com> wrote:
>
> On Mon 05-07-21 09:41:54, David Hildenbrand wrote:
> > On 02.07.21 17:27, Christian Brauner wrote:
> [...]
> > > That one was my favorite from the list I gave too but maybe we can
> > > satisfy Andy too if we use one of:
> > > - process_mfree()
> > > - process_mrelease()
> > >
> >
> > FWIW, I tend to like process_mrelease(), due to the implied "release" ("free
> > the memory if there are no other references") semantics.
>
> Agreed.

Ok, sounds like process_mrelease() would be an acceptable compromise.

>
> > Further, a new
> > syscall feels cleaner than some magic sysfs/procfs toggle. Just my 2 cents.
>
> Yeah, proc based interface is both tricky to use and kinda ugly now that
> pidfd can solve all at in once.

Sounds good. Will keep it as is then.

> My original preference was a more generic kill syscall to allow flags
> but a dedicated syscall doesn't look really bad either.

Yeah, I have tried that direction unsuccessfully before arriving at
this one. Hopefully it represents the right compromise which can
satisfy everyone's usecase.

> --
> Michal Hocko
> SUSE Labs