From: Michal Hocko <mhocko@suse.com>
To: Suren Baghdasaryan <surenb@google.com>
Cc: 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>,
Christian Brauner <christian@brauner.io>,
Oleg Nesterov <oleg@redhat.com>,
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>,
Minchan Kim <minchan@kernel.org>
Subject: Re: [PATCH 1/1] RFC: add pidfd_send_signal flag to reclaim mm while killing a process
Date: Wed, 18 Nov 2020 20:32:33 +0100 [thread overview]
Message-ID: <20201118193233.GV12284@dhcp22.suse.cz> (raw)
In-Reply-To: <CAJuCfpGC1Kv2rC7oq-TT2dX1soy5J_R+y6DU8xEzVuJgOqHKAw@mail.gmail.com>
On Wed 18-11-20 11:22:21, Suren Baghdasaryan wrote:
> On Wed, Nov 18, 2020 at 11:10 AM Michal Hocko <mhocko@suse.com> wrote:
> >
> > On Fri 13-11-20 18:16:32, Andrew Morton wrote:
> > [...]
> > > It's all sounding a bit painful (but not *too* painful). But to
> > > reiterate, I do think that adding the ability for a process to shoot
> > > down a large amount of another process's memory is a lot more generally
> > > useful than tying it to SIGKILL, agree?
> >
> > I am not sure TBH. Is there any reasonable usecase where uncoordinated
> > memory tear down is OK and a target process which is able to see the
> > unmapped memory?
>
> I think uncoordinated memory tear down is a special case which makes
> sense only when the target process is being killed (and we can enforce
> that by allowing MADV_DONTNEED to be used only if the target process
> has pending SIGKILL).
That would be safe but then I am wondering whether it makes sense to
implement as a madvise call. It is quite strange to expect somebody call
a syscall on a killed process. But this is more a detail. I am not a
great fan of a more generic MADV_DONTNEED on a remote process. This is
just too dangerous IMHO.
> However, the ability to apply other flavors of
> process_madvise() to large memory areas spanning multiple VMAs can be
> useful in more cases.
Yes I do agree with that. The error reporting would be more tricky but
I am not really sure that the exact reporting is really necessary for
advice like interface.
> For example in Android we will use
> process_madvise(MADV_PAGEOUT) to "shrink" an inactive background
> process.
That makes sense to me.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2020-11-18 19:32 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-13 17:34 [PATCH 1/1] RFC: add pidfd_send_signal flag to reclaim mm while killing a process Suren Baghdasaryan
2020-11-13 23:55 ` Andrew Morton
2020-11-14 0:06 ` Suren Baghdasaryan
2020-11-14 1:00 ` Andrew Morton
2020-11-14 1:09 ` Suren Baghdasaryan
2020-11-14 1:18 ` Andrew Morton
2020-11-14 1:57 ` Suren Baghdasaryan
2020-11-14 2:16 ` Andrew Morton
2020-11-14 2:51 ` Suren Baghdasaryan
2020-11-16 23:24 ` Minchan Kim
2020-11-18 19:10 ` Michal Hocko
2020-11-18 19:22 ` Suren Baghdasaryan
2020-11-18 19:32 ` Michal Hocko [this message]
2020-11-18 19:51 ` Suren Baghdasaryan
2020-11-18 19:55 ` Suren Baghdasaryan
2020-11-19 0:13 ` Suren Baghdasaryan
2020-11-24 5:45 ` Suren Baghdasaryan
2020-11-18 10:32 ` Christian Brauner
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