Date: Wed, 21 Sep 2005 10:37:01 -0300
From: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
To: Christopher Friesen <cfriesen@nortel.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: help interpreting oom-killer output
Message-ID: <20050921133701.GB5532@dmt.cnet>
References: <43308131.5040104@nortel.com>
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On Tue, Sep 20, 2005 at 03:37:53PM -0600, Christopher Friesen wrote:
> 
> I'm running a modified 2.6.10 on an x86 uniprocessor system.  I keep 
> having processes killed by the oom killer at the same place while 
> running LTP.  The system has gigs of memory, so I find this kind of odd.
> 
> Could someone help me interpret the oom-killer output?  The first log 
> looks like this.
> 
> 
> oom-killer: gfp_mask=0xd0
> DMA per-cpu:
> cpu 0 hot: low 2, high 6, batch 1
> cpu 0 cold: low 0, high 2, batch 1
> Normal per-cpu:
> cpu 0 hot: low 32, high 96, batch 16
> cpu 0 cold: low 0, high 32, batch 16
> HighMem per-cpu:
> cpu 0 hot: low 32, high 96, batch 16
> cpu 0 cold: low 0, high 32, batch 16
> 
> Free pages:     2473820kB (2468096kB HighMem)
> Active:2831 inactive:393 dirty:2 writeback:0 unstable:0 free:618551 
> slab:215125 mapped:1760 pagetables:107
> DMA free:68kB min:68kB low:84kB high:100kB active:0kB inactive:0kB 
> present:16384kB pages_scanned:0 all_unreclaimable? yes

See that the DMA zone free count is equal to the "min" watermark. Normal
and Highmem are both above the "high" watermark.

So this must be a DMA allocation (see gfp_mask). Stick a "dump_stack()" 
to find out who is the allocator.

There have been a lot of changes since v2.6.10 in the OOM killer and reclaim
path.

> protections[]: 0 0 0
> Normal free:7832kB min:3756kB low:4692kB high:5632kB active:0kB 
> inactive:0kB present:901120kB pages_scanned:0 all_unreclaimable? no
> protections[]: 0 0 0
> HighMem free:2468096kB min:512kB low:640kB high:768kB active:11324kB 
> inactive:1572kB present:3276800kB pages_scanned:0 all_unreclaimable? no
> protections[]: 0 0 0
> DMA: 1*4kB 0*8kB 0*16kB 0*32kB 1*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 
> 0*2048kB 0*4096kB = 68kB
> Normal: 10*4kB 8*8kB 13*16kB 1*32kB 5*64kB 1*128kB 7*256kB 3*512kB 
> 2*1024kB 2*2048kB 0*4096kB = 10264kB
> HighMem: 376*4kB 364*8kB 292*16kB 136*32kB 96*64kB 61*128kB 30*256kB 
> 20*512kB 18*1024kB 16*2048kB 579*4096kB = 2468096kB
> Out of Memory: Killed process 17664 (bash).
-
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