Re: [WARNING] lockdep and kmemcheck_alloc_shadow

[Borislav Petkov]

On Mon, Jun 11, 2012 at 02:56:03AM -0700, David Rientjes wrote:
> 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?

Hehe,

this got triggered through a different path too:
http://marc.info/?l=linux-kernel&m=133909780907766

@Rus: Can you pls test David's patch? I'm re-attaching it here.

Thanks.

-- 
Regards/Gruss,
Boris.
From: David Rientjes <rientjes@xxxxxxxxxx>
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@xxxxxxxxxxx>
Suggested-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
---
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) ?