Re: OOM-killer invoked but why ?

[Dhaval Giani]

On Tue, Feb 05, 2008 at 02:07:37AM -0800, Andrew Morton wrote:
> On Thu, 31 Jan 2008 13:53:05 +0100 Claude Frantz <r31dmaeu@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> 
> > Hello !
> > 
> > I'm faced to a problem where the OOM-killer is invoked but I cannot find
> > the reason why. The machine is rather powerfull, the load is very moderate,
> > the disk swap space is nearly unused. The only strange observation which
> > appears to me is the slow but progressive decreasing of kbbuffers during
> > many hours.
> > 
> > Can you help me to diagnose the problem and to find a good solution ?
> > 
> > ...
> >
> > Jan 28 03:50:49 toaster kernel: 177466 pages slab
> > Jan 28 03:50:49 toaster kernel: 1915 pages pagetables
> > Jan 28 03:50:49 toaster kernel: Out of memory: kill process 10859 (amavisd) score 36218 or a child
> > Jan 28 03:50:49 toaster kernel: Killed process 19146 (amavisd)
> 
> slab.  Maybe you've been bitten by the quicklist leak.  If you're able to
> patch your kernel then please try this fix:
> 
> commit 96990a4ae979df9e235d01097d6175759331e88c
> Author: Christoph Lameter <clameter@xxxxxxx>
> Date:   Mon Jan 14 00:55:14 2008 -0800
> 
>     quicklists: Only consider memory that can be used with GFP_KERNEL
>     
>     Quicklists calculates the size of the quicklists based on the number of
>     free pages.  This must be the number of free pages that can be allocated
>     with GFP_KERNEL.  node_page_state() includes the pages in ZONE_HIGHMEM and
>     ZONE_MOVABLE which may lead the quicklists to become too large causing OOM.
>     
>     Signed-off-by: Christoph Lameter <clameter@xxxxxxx>
>     Tested-by: Dhaval Giani <dhaval@xxxxxxxxxxxxxxxxxx>
>     Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>     Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> 
> diff --git a/mm/quicklist.c b/mm/quicklist.c
> index ae8189c..3f703f7 100644
> --- a/mm/quicklist.c
> +++ b/mm/quicklist.c
> @@ -26,9 +26,17 @@ DEFINE_PER_CPU(struct quicklist, quicklist)[CONFIG_NR_QUICK];
>  static unsigned long max_pages(unsigned long min_pages)
>  {
>  	unsigned long node_free_pages, max;
> +	struct zone *zones = NODE_DATA(numa_node_id())->node_zones;
> +
> +	node_free_pages =
> +#ifdef CONFIG_ZONE_DMA
> +		zone_page_state(&zones[ZONE_DMA], NR_FREE_PAGES) +
> +#endif
> +#ifdef CONFIG_ZONE_DMA32
> +		zone_page_state(&zones[ZONE_DMA32], NR_FREE_PAGES) +
> +#endif
> +		zone_page_state(&zones[ZONE_NORMAL], NR_FREE_PAGES);
> 
> -	node_free_pages = node_page_state(numa_node_id(),
> -			NR_FREE_PAGES);
>  	max = node_free_pages / FRACTION_OF_NODE_MEM;
>  	return max(max, min_pages);
>  }
> 
> 
> I note that this didn't have the stable@xxxxxxxxxx cc.  Christoph, did we
> deliberately decide not to backport?
> 

According to
http://archive.netbsd.se/?ml=linux-stable-commits&a=2008-01&m=6134301 ,
its been added to the stable tree. I remember asking Greg to add it.

Thanks
-- 
regards,
Dhaval
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