From: Michal Hocko <mhocko@kernel.org>
To: Hugh Dickins <hughd@google.com>
Cc: David Rientjes <rientjes@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@suse.de>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
Oleg Nesterov <oleg@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrea Argangeli <andrea@kernel.org>,
Rik van Riel <riel@redhat.com>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/5] oom reaper: handle mlocked pages
Date: Mon, 29 Feb 2016 14:41:39 +0100 [thread overview]
Message-ID: <20160229134139.GB16930@dhcp22.suse.cz> (raw)
In-Reply-To: <alpine.LSU.2.11.1602281844180.3975@eggly.anvils>
On Sun 28-02-16 19:19:11, Hugh Dickins wrote:
> On Tue, 23 Feb 2016, Michal Hocko wrote:
> > On Mon 22-02-16 17:36:07, David Rientjes wrote:
> > >
> > > Are we concerned about munlock_vma_pages_all() taking lock_page() and
> > > perhaps stalling forever, the same way it would stall in exit_mmap() for
> > > VM_LOCKED vmas, if another thread has locked the same page and is doing an
> > > allocation?
> >
> > This is a good question. I have checked for that particular case
> > previously and managed to convinced myself that this is OK(ish).
> > munlock_vma_pages_range locks only THP pages to prevent from the
> > parallel split-up AFAICS.
>
> I think you're mistaken on that: there is also the lock_page()
> on every page in Phase 2 of __munlock_pagevec().
Ohh, I have missed that one. Thanks for pointing it out!
[...]
> > Just for the reference this is what I came up with (just compile tested).
>
> I tried something similar internally (on an earlier kernel). Like
> you I've set that work aside for now, there were quicker ways to fix
> the issue at hand. But it does continue to offend me that munlock
> demands all those page locks: so if you don't get back to it before me,
> I shall eventually.
>
> I didn't understand why you complicated yours with the "enforce"
> arg to munlock_vma_pages_range(): why not just trylock in all cases?
Well, I have to confess that I am not really sure I understand all the
consequences of the locking here. It has always been subtle and weird
issues popping up from time to time. So I only wanted to have that
change limitted to the oom_reaper. So I would really appreciate if
somebody more knowledgeable had a look. We can drop the mlock patch for
now.
Thanks for looking into this, Hugh!
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2016-02-29 13:41 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-03 13:13 [PATCH 0/5] oom reaper v5 Michal Hocko
2016-02-03 13:13 ` [PATCH 1/5] mm, oom: introduce oom reaper Michal Hocko
2016-02-03 23:48 ` David Rientjes
2016-02-04 6:41 ` Michal Hocko
2016-02-06 13:22 ` Tetsuo Handa
2016-02-15 20:50 ` Michal Hocko
2016-02-03 13:13 ` [PATCH 2/5] oom reaper: handle mlocked pages Michal Hocko
2016-02-03 23:57 ` David Rientjes
2016-02-23 1:36 ` David Rientjes
2016-02-23 13:21 ` Michal Hocko
2016-02-29 3:19 ` Hugh Dickins
2016-02-29 13:41 ` Michal Hocko [this message]
2016-03-08 13:40 ` Michal Hocko
2016-03-08 20:07 ` Hugh Dickins
2016-03-09 8:26 ` Michal Hocko
2016-02-03 13:13 ` [PATCH 3/5] oom: clear TIF_MEMDIE after oom_reaper managed to unmap the address space Michal Hocko
2016-02-04 14:22 ` Tetsuo Handa
2016-02-04 14:43 ` Michal Hocko
2016-02-04 15:08 ` Tetsuo Handa
2016-02-04 16:31 ` Michal Hocko
2016-02-05 11:14 ` Tetsuo Handa
2016-02-06 8:30 ` Michal Hocko
2016-02-06 11:23 ` Tetsuo Handa
2016-02-15 20:47 ` Michal Hocko
2016-02-06 6:45 ` Michal Hocko
2016-02-06 14:33 ` Tetsuo Handa
2016-02-15 20:40 ` [PATCH 3.1/5] oom: make oom_reaper freezable Michal Hocko
2016-02-03 13:13 ` [PATCH 4/5] mm, oom_reaper: report success/failure Michal Hocko
2016-02-03 23:10 ` David Rientjes
2016-02-04 6:46 ` Michal Hocko
2016-02-04 22:31 ` David Rientjes
2016-02-05 9:26 ` Michal Hocko
2016-02-06 6:34 ` Michal Hocko
2016-02-03 13:14 ` [PATCH 5/5] mm, oom_reaper: implement OOM victims queuing Michal Hocko
2016-02-04 10:49 ` Tetsuo Handa
2016-02-04 14:53 ` Michal Hocko
2016-02-06 5:54 ` Tetsuo Handa
2016-02-06 8:37 ` Michal Hocko
2016-02-06 15:33 ` Tetsuo Handa
2016-02-15 20:15 ` Michal Hocko
2016-02-16 11:11 ` Tetsuo Handa
2016-02-16 15:53 ` Michal Hocko
2016-02-17 9:48 ` [PATCH 6/5] oom, oom_reaper: disable oom_reaper for Michal Hocko
2016-02-17 10:41 ` Tetsuo Handa
2016-02-17 11:33 ` Michal Hocko
2016-02-19 18:34 ` Michal Hocko
2016-02-20 2:32 ` [PATCH 6/5] oom, oom_reaper: disable oom_reaper for oom_kill_allocating_task Tetsuo Handa
2016-02-22 9:41 ` Michal Hocko
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