Subject: Re: kernel BUG in __cache_alloc_node at linux-2.6.git/mm/slab.c:3177!

From: Andy Whitcroft <[email-masked]>
Date: Fri, 20 Oct 2006 19:07:29 +0100

Christoph Lameter wrote:
> Here is the patch:
> 
> Slab: Do not fallback to nodes that have not been bootstrapped yet
> 
> The zonelist may contain zones of nodes that have not been bootstrapped 
> and we will oops if we try to allocate from those zones. So check if the 
> node information for the slab and the node have been setup before 
> attempting an allocation. If it has not been setup then skip that zone.
> 
> Usually we will not encounter this situation since the slab bootstrap
> code avoids falling back before we have setup the respective nodes but we 
> seem to have a special needs for pppc.
> 
> Signed-off-by: Christoph Lameter <[email-masked]>
> 
> Index: linux-2.6.19-rc2-mm1/mm/slab.c
> ===================================================================
> --- linux-2.6.19-rc2-mm1.orig/mm/slab.c	2006-10-20 12:39:02.000000000 -0500
> +++ linux-2.6.19-rc2-mm1/mm/slab.c	2006-10-20 12:41:04.137684581 -0500
> @@ -3160,12 +3160,15 @@ void *fallback_alloc(struct kmem_cache *
>  	struct zone **z;
>  	void *obj = NULL;
>  
> -	for (z = zonelist->zones; *z && !obj; z++)
> +	for (z = zonelist->zones; *z && !obj; z++) {
> +		int nid = zone_to_nid(*z);
> +
>  		if (zone_idx(*z) <= ZONE_NORMAL &&
> -				cpuset_zone_allowed(*z, flags))
> +				cpuset_zone_allowed(*z, flags) &&
> +				cache->nodelists[nid])
>  			obj = __cache_alloc_node(cache,
> -					flags | __GFP_THISNODE,
> -					zone_to_nid(*z));
> +					flags | __GFP_THISNODE, nid);
> +	}
>  	return obj;
>  }
>  
> 

Applied this and the previous version, diff says they are identicle, so
my previous testing applies.

Acked-by: Andy Whitcroft <[email-masked]>

-apw