linux-kernel - Re: oomkillers gone wild.

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Message-ID: <20120608200317.GA18693@redhat.com>
Date:	Fri, 8 Jun 2012 16:03:17 -0400
From:	Dave Jones <davej@...hat.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Linux Kernel <linux-kernel@...r.kernel.org>, linux-mm@...ck.org
Subject: Re: oomkillers gone wild.

On Fri, Jun 08, 2012 at 12:57:36PM -0700, David Rientjes wrote:
 > On Tue, 5 Jun 2012, Dave Jones wrote:
 > 
 > >   OBJS ACTIVE  USE OBJ SIZE  SLABS OBJ/SLAB CACHE SIZE NAME 
 > > 142524 142420  99%    9.67K  47510	  3   1520320K task_struct
 > > 142560 142417  99%    1.75K   7920	 18    253440K signal_cache
 > > 142428 142302  99%    1.19K   5478	 26    175296K task_xstate
 > > 306064 289292  94%    0.36K   6956	 44    111296K debug_objects_cache
 > > 143488 143306  99%    0.50K   4484	 32     71744K cred_jar
 > > 142560 142421  99%    0.50K   4455       32     71280K task_delay_info
 > > 150753 145021  96%    0.45K   4308	 35     68928K kmalloc-128
 > > 
 > > Why so many task_structs ? There's only 128 processes running, and most of them
 > > are kernel threads.
 > > 
 > 
 > Do you have CONFIG_OPROFILE enabled?

it's modular (though I should just turn it off, I never use it these days), but not loaded.

 > > /sys/kernel/slab/task_struct/alloc_calls shows..
 > > 
 > >  142421 copy_process.part.21+0xbb/0x1790 age=8/19929576/48173720 pid=0-16867 cpus=0-7
 > > 
 > > I get the impression that the oom-killer hasn't cleaned up properly after killing some of
 > > those forked processes.
 > > 
 > > any thoughts ?
 > > 
 > 
 > If we're leaking task_struct's, meaning that put_task_struct() isn't 
 > actually freeing them when the refcount goes to 0, then it's certainly not 
 > because of the oom killer which only sends a SIGKILL to the selected 
 > process.
 > 
 > Have you tried kmemleak?

I'll give that a shot on Monday. thanks,

	Dave
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