Re: [PATCH 1/1] mm: introduce process_reap system call

From: Suren Baghdasaryan <surenb@google.com>
To: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Michal Hocko <mhocko@suse.com>,
	David Hildenbrand <david@redhat.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>
Subject: Re: [PATCH 1/1] mm: introduce process_reap system call
Date: Fri, 9 Jul 2021 13:05:38 -0700	[thread overview]
Message-ID: <CAJuCfpGgZQLso6VKm5QXMJok1iuioWiLGF0b2W+VbQOzqaKYww@mail.gmail.com> (raw)
In-Reply-To: <20210709085857.zf5ik3btet3yw4ab@wittgenstein>

On Fri, Jul 9, 2021 at 1:59 AM Christian Brauner
<christian.brauner@ubuntu.com> wrote:
>
> On Wed, Jul 07, 2021 at 02:14:23PM -0700, Suren Baghdasaryan wrote:
> > 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.
>
> I think a syscall is fine and it's not we're running out of numbers
> (anymore). :)

Thanks everyone for the input!
So far I collected:
1. rename the syscall to process_mrelease()
2. replace "dying process" with "process which was sent a SIGKILL
signal" in the manual page text

I'll respin a v2 with these changes next week.
Have a great weekend!
Suren.

>
> Christian