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From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	Michal Hocko <mhocko@kernel.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch] mm, oom: prevent soft lockup on memcg oom for UP systems
Date: Thu, 12 Mar 2020 09:12:14 +0900	[thread overview]
Message-ID: <202003120012.02C0CEUB043533@www262.sakura.ne.jp> (raw)
In-Reply-To: <alpine.DEB.2.21.2003111513180.195367@chino.kir.corp.google.com>

> On Thu, 12 Mar 2020, Tetsuo Handa wrote:
> > > If you have an alternate patch to try, we can test it.  But since this 
> > > cond_resched() is needed anyway, I'm not sure it will change the result.
> > 
> > schedule_timeout_killable(1) is an alternate patch to try; I don't think
> > that this cond_resched() is needed anyway.
> > 
> 
> You are suggesting schedule_timeout_killable(1) in shrink_node_memcgs()?
> 

Andrew Morton also mentioned whether cond_resched() in shrink_node_memcgs()
is enough. But like you mentioned,

David Rientjes wrote:
> On Tue, 10 Mar 2020, Andrew Morton wrote:
> 
> > > --- a/mm/vmscan.c
> > > +++ b/mm/vmscan.c
> > > @@ -2637,6 +2637,8 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
> > >  		unsigned long reclaimed;
> > >  		unsigned long scanned;
> > >  
> > > +		cond_resched();
> > > +
> > >  		switch (mem_cgroup_protected(target_memcg, memcg)) {
> > >  		case MEMCG_PROT_MIN:
> > >  			/*
> > 
> > 
> > Obviously better, but this will still spin wheels until this tasks's
> > timeslice expires, and we might want to do something to help ensure
> > that the victim runs next (or soon)?
> > 
> 
> We used to have a schedule_timeout_killable(1) to address exactly that 
> scenario but it was removed in 4.19:
> 
> commit 9bfe5ded054b8e28a94c78580f233d6879a00146
> Author: Michal Hocko <mhocko@suse.com>
> Date:   Fri Aug 17 15:49:04 2018 -0700
> 
>     mm, oom: remove sleep from under oom_lock

you can try re-adding sleep outside of oom_lock:

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d09776cd6e10..3aee7e0eca4e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1576,6 +1576,7 @@ static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
 	 */
 	ret = should_force_charge() || out_of_memory(&oc);
 	mutex_unlock(&oom_lock);
+	schedule_timeout_killable(1);
 	return ret;
 }
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3c4eb750a199..e80158049651 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3797,7 +3797,6 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
 	 */
 	if (!mutex_trylock(&oom_lock)) {
 		*did_some_progress = 1;
-		schedule_timeout_uninterruptible(1);
 		return NULL;
 	}
 
@@ -4590,6 +4589,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 
 	/* Retry as long as the OOM killer is making progress */
 	if (did_some_progress) {
+		schedule_timeout_uninterruptible(1);
 		no_progress_loops = 0;
 		goto retry;
 	}

By the way, will you share the reproducer (and how to use the reproducer) ?


  reply	other threads:[~2020-03-12  0:12 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-10 21:39 [patch] mm, oom: prevent soft lockup on memcg oom for UP systems David Rientjes
2020-03-10 22:05 ` Tetsuo Handa
2020-03-10 22:55   ` David Rientjes
2020-03-11  9:34     ` Tetsuo Handa
2020-03-11 19:38       ` David Rientjes
2020-03-11 22:04         ` Tetsuo Handa
2020-03-11 22:14           ` David Rientjes
2020-03-12  0:12             ` Tetsuo Handa [this message]
2020-03-12 18:07               ` David Rientjes
2020-03-12 22:32                 ` Andrew Morton
2020-03-16  9:31                   ` Michal Hocko
2020-03-16 10:04                     ` Tetsuo Handa
2020-03-16 10:14                       ` Michal Hocko
2020-03-13  0:15                 ` Tetsuo Handa
2020-03-13 22:01                   ` David Rientjes
2020-03-13 23:15                     ` Tetsuo Handa
2020-03-13 23:32                       ` Tetsuo Handa
2020-03-16 23:59                         ` David Rientjes
2020-03-17  3:18                           ` Tetsuo Handa
2020-03-17  4:09                             ` David Rientjes
2020-03-18  0:55                               ` [patch v2] " David Rientjes
2020-03-18  9:42                                 ` Michal Hocko
2020-03-18 21:40                                   ` David Rientjes
2020-03-18 22:03                                     ` [patch v3] " David Rientjes
2020-03-19  7:09                                       ` Michal Hocko
2020-03-12  4:23             ` [patch] " Tetsuo Handa
2020-03-10 22:10 ` Michal Hocko
2020-03-10 23:02   ` David Rientjes
2020-03-11  8:27     ` Michal Hocko
2020-03-11 19:45       ` David Rientjes
2020-03-12  8:32         ` Michal Hocko
2020-03-12 18:20           ` David Rientjes
2020-03-12 20:16             ` Michal Hocko
2020-03-16  9:32               ` Michal Hocko
2020-03-11  0:18 ` Andrew Morton
2020-03-11  0:34   ` David Rientjes
2020-03-11  8:36   ` Michal Hocko

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