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

From: Will Schmidt
Date: Fri Oct 13 2006 - 15:54:14 EST


On Fri, 2006-13-10 at 12:05 -0700, Christoph Lameter wrote:
> On Fri, 13 Oct 2006, Will Schmidt wrote:
>
> > Am seeing a crash on a power5 LPAR when booting the linux-2.6 git
> > tree. It's fairly early during boot, so I've included the whole log
> > below. This partition has 8 procs, (shared, including threads), and
> > 512M RAM.
>
> This looks like slab bootstrap. You are bootstrapping while having
> zonelists build with zones that are only going to be populated later?
> This will lead to incorrect NUMA placement of lots of slab structures on
> bootup.

I dont think so.. but it's not an area I'm very familiar with. one
of the other PPC folks might chime in with something here.

>
> Check if the patch below may cure the oops. Your memory is likely
> still placed on the wrong numa nodes since we have to fallback from
> the intended node.

Nope, no change with this patch.

>
> Index: linux-2.6/mm/slab.c
> ===================================================================
> --- linux-2.6.orig/mm/slab.c 2006-10-13 11:59:55.000000000 -0700
> +++ linux-2.6/mm/slab.c 2006-10-13 12:03:15.000000000 -0700
> @@ -3154,7 +3154,8 @@ void *fallback_alloc(struct kmem_cache *
>
> for (z = zonelist->zones; *z && !obj; z++)
> if (zone_idx(*z) <= ZONE_NORMAL &&
> - cpuset_zone_allowed(*z, flags))
> + cpuset_zone_allowed(*z, flags) &&
> + (*z)->free_pages)
> obj = __cache_alloc_node(cache,
> flags | __GFP_THISNODE,
> zone_to_nid(*z));

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