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Date: Mon, 11 Jun 2012 02:56:03 -0700 (PDT)
From: David Rientjes <rientjes@google.com>
X-X-Sender: rientjes@chino.kir.corp.google.com
To: Ben Hutchings <ben@decadent.org.uk>, Steven Rostedt <rostedt@goodmis.org>
cc: Christoph Lameter <cl@linux.com>, LKML <linux-kernel@vger.kernel.org>,
        stable <stable@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Peter Zijlstra <peterz@infradead.org>
Subject: Re: [WARNING] lockdep and kmemcheck_alloc_shadow
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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 <rostedt@goodmis.org>
> Suggested-by: Ben Hutchings <ben@decadent.org.uk>
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
> 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) ?
>