linux-kernel - Re: [PATCH] oom_kill: add option to disable dump

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Message-ID: <alpine.DEB.2.10.1512011602170.15908@chino.kir.corp.google.com>
Date:	Tue, 1 Dec 2015 16:02:54 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
cc:	Aristeu Rozanski <arozansk@...hat.com>,
	linux-kernel@...r.kernel.org, Greg Thelen <gthelen@...gle.com>,
	Johannes Weiner <hannes@...xchg.org>, linux-mm@...ck.org,
	cgroups@...r.kernel.org
Subject: Re: [PATCH] oom_kill: add option to disable dump_stack()

On Tue, 1 Dec 2015, Andrew Morton wrote:

> > --- a/include/linux/oom.h
> > +++ b/include/linux/oom.h
> > @@ -115,6 +115,7 @@ static inline bool task_will_free_mem(struct task_struct *task)
> >  
> >  /* sysctls */
> >  extern int sysctl_oom_dump_tasks;
> > +extern int sysctl_oom_dump_stack;
> >  extern int sysctl_oom_kill_allocating_task;
> >  extern int sysctl_panic_on_oom;
> >  #endif /* _INCLUDE_LINUX_OOM_H */
> > diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> > index e69201d..c812523 100644
> > --- a/kernel/sysctl.c
> > +++ b/kernel/sysctl.c
> > @@ -1176,6 +1176,13 @@ static struct ctl_table vm_table[] = {
> >  		.proc_handler	= proc_dointvec,
> >  	},
> >  	{
> > +		.procname	= "oom_dump_stack",
> > +		.data		= &sysctl_oom_dump_stack,
> > +		.maxlen		= sizeof(sysctl_oom_dump_stack),
> > +		.mode		= 0644,
> > +		.proc_handler	= proc_dointvec,
> > +	},
> > +	{
> >  		.procname	= "overcommit_ratio",
> >  		.data		= &sysctl_overcommit_ratio,
> >  		.maxlen		= sizeof(sysctl_overcommit_ratio),
> > diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> > index 1ecc0bc..bdbf83b 100644
> > --- a/mm/oom_kill.c
> > +++ b/mm/oom_kill.c
> > @@ -42,6 +42,7 @@
> >  int sysctl_panic_on_oom;
> >  int sysctl_oom_kill_allocating_task;
> >  int sysctl_oom_dump_tasks = 1;
> > +int sysctl_oom_dump_stack = 1;
> >  
> >  DEFINE_MUTEX(oom_lock);
> >  
> > @@ -384,7 +385,8 @@ static void dump_header(struct oom_control *oc, struct task_struct *p,
> >  		current->signal->oom_score_adj);
> >  	cpuset_print_task_mems_allowed(current);
> >  	task_unlock(current);
> > -	dump_stack();
> > +	if (sysctl_oom_dump_stack)
> > +		dump_stack();
> >  	if (memcg)
> >  		mem_cgroup_print_oom_info(memcg, p);
> >  	else
> 
> The patch seems reasonable to me, but it's missing the required update
> to Documentation/sysctl/vm.txt.
> 

Not sure why we'd want yet-another-sysctl for something that can trivially 
filtered from the log, but owell.
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