Re: slub: use irqsafe_cpu_cmpxchg for put_cpu_partial

[Christian Kujau <lists@nerdbynature.de>]

On Wed, 23 Nov 2011 at 09:14, Christoph Lameter wrote:
> I think he only tested the patch that he showed us.

Yes, that's the (only) one I tested so far. I did some overnight testing 
(rsync'ing to the external disk again) for 6hrs and ran "slabinfo" every 
30s during the run: http://nerdbynature.de/bits/3.2.0-rc1/oops/slabinfo-1.txt.xz

The machine is still up & running. So for me, your patch fixes it!

  Tested-by: Christian Kujau <lists@nerdbynature.de>

Thanks!
Christian.

> Subject: slub: use irqsafe_cpu_cmpxchg for put_cpu_partial
> 
> The cmpxchg must be irq safe. The fallback for this_cpu_cmpxchg only
> disables preemption which results in per cpu partial page operation
> potentially failing on non x86 platforms.
> 
> Signed-off-by: Christoph Lameter <cl@linux.com>
> 
> ---
>  mm/slub.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Index: linux-2.6/mm/slub.c
> ===================================================================
> --- linux-2.6.orig/mm/slub.c	2011-11-23 09:10:48.000000000 -0600
> +++ linux-2.6/mm/slub.c	2011-11-23 09:10:57.000000000 -0600
> @@ -1969,7 +1969,7 @@ int put_cpu_partial(struct kmem_cache *s
>  		page->pobjects = pobjects;
>  		page->next = oldpage;
> 
> -	} while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) != oldpage);
> +	} while (irqsafe_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) != oldpage);
>  	stat(s, CPU_PARTIAL_FREE);
>  	return pobjects;
>  }
> 

-- 
BOFH excuse #43:

boss forgot system password

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