On Sun, 20 May 2012, David Rientjes wrote:

> Agreed, slab handles this correctly and it looks like slub ends up 
> disabling irqs too early.
> 
> Does this fix it?  If so, we'll need to annotate it for stable as Ben 
> noted.
> 

Steven, did you have a chance to see if this fixes the issue for you?  Can 
I add your Tested-by?

> mm, slub: ensure irqs are not disabled for kmemcheck allocation
> 
> kmemcheck_alloc_shadow() cannot be called with irqs disabled, which is
> possible with __GFP_WAIT.  Ensure we always have them enabled at
> allocation time like slab does.
> 
> Reported-by: Steven Rostedt <[email protected]>
> Suggested-by: Ben Hutchings <[email protected]>
> Signed-off-by: David Rientjes <[email protected]>
> ---
> diff --git a/mm/slub.c b/mm/slub.c
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1314,13 +1314,7 @@ static struct page *allocate_slab(struct kmem_cache 
> *s, gfp_t flags, int node)
>                       stat(s, ORDER_FALLBACK);
>       }
>  
> -     if (flags & __GFP_WAIT)
> -             local_irq_disable();
> -
> -     if (!page)
> -             return NULL;
> -
> -     if (kmemcheck_enabled
> +     if (page && kmemcheck_enabled
>               && !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS))) {
>               int pages = 1 << oo_order(oo);
>  
> @@ -1336,6 +1330,11 @@ static struct page *allocate_slab(struct kmem_cache 
> *s, gfp_t flags, int node)
>                       kmemcheck_mark_unallocated_pages(page, pages);
>       }
>  
> +     if (flags & __GFP_WAIT)
> +             local_irq_disable();
> +     if (!page)
> +             return NULL;
> +
>       page->objects = oo_objects(oo);
>       mod_zone_page_state(page_zone(page),
>               (s->flags & SLAB_RECLAIM_ACCOUNT) ?
> 
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