From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: mhocko@kernel.org, rientjes@google.com
Cc: oleg@redhat.com, torvalds@linux-foundation.org,
kwalker@redhat.com, cl@linux.com, akpm@linux-foundation.org,
hannes@cmpxchg.org, vdavydov@parallels.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, skozina@redhat.com
Subject: Re: can't oom-kill zap the victim's memory?
Date: Sat, 26 Sep 2015 01:14:50 +0900 [thread overview]
Message-ID: <201509260114.ADI35946.OtHOVFOMJQFLFS@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <20150925093556.GF16497@dhcp22.suse.cz>
Michal Hocko wrote:
> On Thu 24-09-15 14:15:34, David Rientjes wrote:
> > > > Finally. Whatever we do, we need to change oom_kill_process() first,
> > > > and I think we should do this regardless. The "Kill all user processes
> > > > sharing victim->mm" logic looks wrong and suboptimal/overcomplicated.
> > > > I'll try to make some patches tomorrow if I have time...
> > >
> > > That would be appreciated. I do not like that part either. At least we
> > > shouldn't go over the whole list when we have a good chance that the mm
> > > is not shared with other processes.
> > >
> >
> > Heh, it's actually imperative to avoid livelocking based on mm->mmap_sem,
> > it's the reason the code exists. Any optimizations to that is certainly
> > welcome, but we definitely need to send SIGKILL to all threads sharing the
> > mm to make forward progress, otherwise we are going back to pre-2008
> > livelocks.
>
> Yes but mm is not shared between processes most of the time. CLONE_VM
> without CLONE_THREAD is more a corner case yet we have to crawl all the
> task_structs for _each_ OOM killer invocation. Yes this is an extreme
> slow path but still might take quite some unnecessarily time.
Excuse me, but thinking about CLONE_VM without CLONE_THREAD case...
Isn't there possibility of hitting livelocks at
/*
* If current has a pending SIGKILL or is exiting, then automatically
* select it. The goal is to allow it to allocate so that it may
* quickly exit and free its memory.
*
* But don't select if current has already released its mm and cleared
* TIF_MEMDIE flag at exit_mm(), otherwise an OOM livelock may occur.
*/
if (current->mm &&
(fatal_signal_pending(current) || task_will_free_mem(current))) {
mark_oom_victim(current);
return true;
}
if current thread receives SIGKILL just before reaching here, for we don't
send SIGKILL to all threads sharing the mm?
Hopefully current thread is not holding inode->i_mutex because reaching here
(i.e. calling out_of_memory()) suggests that we are doing GFP_KERNEL
allocation. But it could be !__GFP_NOFS && __GFP_NOFAIL allocation, or
different locks contended by another thread sharing the mm?
I don't like "That thread will now get access to memory reserves since it
has a pending fatal signal." line in comments for the "Kill all user
processes sharing victim->mm" logic. That thread won't get access to memory
reserves unless that thread can call out_of_memory() (i.e. doing __GFP_FS or
__GFP_NOFAIL allocations). Since I can observe that that thread may be doing
!__GFP_NOFS allocation, I think that this comment needs to be updated.
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next prev parent reply other threads:[~2015-09-25 16:15 UTC|newest]
Thread overview: 109+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-17 17:59 [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Kyle Walker
2015-09-17 19:22 ` Oleg Nesterov
2015-09-18 15:41 ` Christoph Lameter
2015-09-18 16:24 ` Oleg Nesterov
2015-09-18 16:39 ` Tetsuo Handa
2015-09-18 16:54 ` Oleg Nesterov
2015-09-18 17:00 ` Christoph Lameter
2015-09-18 19:07 ` Oleg Nesterov
2015-09-18 19:19 ` Christoph Lameter
2015-09-18 21:28 ` Kyle Walker
2015-09-18 22:07 ` Christoph Lameter
2015-09-19 8:32 ` Michal Hocko
2015-09-19 14:33 ` Tetsuo Handa
2015-09-19 15:51 ` Michal Hocko
2015-09-21 23:33 ` David Rientjes
2015-09-22 5:33 ` Tetsuo Handa
2015-09-22 23:32 ` David Rientjes
2015-09-23 12:03 ` Kyle Walker
2015-09-24 11:50 ` Tetsuo Handa
2015-09-19 14:44 ` Oleg Nesterov
2015-09-21 23:27 ` David Rientjes
2015-09-19 8:25 ` Michal Hocko
2015-09-19 8:22 ` Michal Hocko
2015-09-21 23:08 ` David Rientjes
2015-09-19 15:03 ` can't oom-kill zap the victim's memory? Oleg Nesterov
2015-09-19 15:10 ` Oleg Nesterov
2015-09-19 15:58 ` Michal Hocko
2015-09-20 13:16 ` Oleg Nesterov
2015-09-19 22:24 ` Linus Torvalds
2015-09-19 22:54 ` Raymond Jennings
2015-09-19 23:00 ` Raymond Jennings
2015-09-19 23:13 ` Linus Torvalds
2015-09-20 9:33 ` Michal Hocko
2015-09-20 13:06 ` Oleg Nesterov
2015-09-20 12:56 ` Oleg Nesterov
2015-09-20 18:05 ` Linus Torvalds
2015-09-20 18:21 ` Raymond Jennings
2015-09-20 18:23 ` Raymond Jennings
2015-09-20 19:07 ` Raymond Jennings
2015-09-21 13:57 ` Oleg Nesterov
2015-09-21 13:44 ` Oleg Nesterov
2015-09-21 14:24 ` Michal Hocko
2015-09-21 15:32 ` Oleg Nesterov
2015-09-21 16:12 ` Michal Hocko
2015-09-22 16:06 ` Oleg Nesterov
2015-09-22 23:04 ` David Rientjes
2015-09-23 20:59 ` Michal Hocko
2015-09-24 21:15 ` David Rientjes
2015-09-25 9:35 ` Michal Hocko
2015-09-25 16:14 ` Tetsuo Handa [this message]
2015-09-28 16:18 ` Tetsuo Handa
2015-09-28 22:28 ` David Rientjes
2015-10-02 12:36 ` Michal Hocko
2015-10-02 19:01 ` Linus Torvalds
2015-10-05 14:44 ` Michal Hocko
2015-10-07 5:16 ` Vlastimil Babka
2015-10-07 10:43 ` Tetsuo Handa
2015-10-08 9:40 ` Vlastimil Babka
2015-10-06 7:55 ` Eric W. Biederman
2015-10-06 8:49 ` Linus Torvalds
2015-10-06 8:55 ` Linus Torvalds
2015-10-06 14:52 ` Eric W. Biederman
2015-10-03 6:02 ` Can't we use timeout based OOM warning/killing? Tetsuo Handa
2015-10-06 14:51 ` Tetsuo Handa
2015-10-12 6:43 ` Tetsuo Handa
2015-10-12 15:25 ` Silent hang up caused by pages being not scanned? Tetsuo Handa
2015-10-12 21:23 ` Linus Torvalds
2015-10-13 12:21 ` Tetsuo Handa
2015-10-13 16:37 ` Linus Torvalds
2015-10-14 12:21 ` Tetsuo Handa
2015-10-15 13:14 ` Michal Hocko
2015-10-16 15:57 ` Michal Hocko
2015-10-16 18:34 ` Linus Torvalds
2015-10-16 18:49 ` Tetsuo Handa
2015-10-19 12:57 ` Michal Hocko
2015-10-19 12:53 ` Michal Hocko
2015-10-13 13:32 ` Michal Hocko
2015-10-13 16:19 ` Tetsuo Handa
2015-10-14 13:22 ` Michal Hocko
2015-10-14 14:38 ` Tetsuo Handa
2015-10-14 14:59 ` Michal Hocko
2015-10-14 15:06 ` Tetsuo Handa
2015-10-26 11:44 ` Newbie's question: memory allocation when reclaiming memory Tetsuo Handa
2015-11-05 8:46 ` Vlastimil Babka
2015-10-06 15:25 ` Can't we use timeout based OOM warning/killing? Linus Torvalds
2015-10-08 15:33 ` Tetsuo Handa
2015-10-10 12:50 ` Tetsuo Handa
2015-09-28 22:24 ` can't oom-kill zap the victim's memory? David Rientjes
2015-09-29 7:57 ` Tetsuo Handa
2015-09-29 22:56 ` David Rientjes
2015-09-30 4:25 ` Tetsuo Handa
2015-09-30 10:21 ` Tetsuo Handa
2015-09-30 21:11 ` David Rientjes
2015-10-01 12:13 ` Tetsuo Handa
2015-10-01 14:48 ` Michal Hocko
2015-10-02 13:06 ` Tetsuo Handa
2015-10-06 18:45 ` Oleg Nesterov
2015-10-07 11:03 ` Tetsuo Handa
2015-10-07 12:00 ` Oleg Nesterov
2015-10-08 14:04 ` Michal Hocko
2015-10-08 14:01 ` Michal Hocko
2015-09-21 16:51 ` Tetsuo Handa
2015-09-22 12:43 ` Oleg Nesterov
2015-09-22 14:30 ` Tetsuo Handa
2015-09-22 14:45 ` Oleg Nesterov
2015-09-21 23:42 ` David Rientjes
2015-09-21 16:55 ` Linus Torvalds
2015-09-20 14:50 ` Tetsuo Handa
2015-09-20 14:55 ` Oleg Nesterov
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