linux-kernel - Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known regressions with patches]

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Message-Id: <1185441963.8197.67.camel@twins>
Date:	Thu, 26 Jul 2007 11:26:03 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Michal Piotrowski <michal.k.k.piotrowski@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <clameter@....com>,
	linux-kernel@...r.kernel.org
Subject: Re: [bug] SLUB & freeing locks [was: Re: 2.6.23-rc1: known
	regressions with patches]

On Thu, 2007-07-26 at 11:10 +0200, Ingo Molnar wrote:
> there's a new regression:
> 
> SLUB does not seem to call debug_check_no_locks_freed() - hence on SLUB 
> we will not notice certain types of freeing races. (such as freeing an 
> object still locked and used on another CPU.) SLAB does this corretly.

Does this help?

---
 mm/slub.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c
+++ linux-2.6/mm/slub.c
@@ -1131,6 +1131,7 @@ static void __free_slab(struct kmem_cach
 		slab_pad_check(s, page);
 		for_each_object(p, s, page_address(page))
 			check_object(s, page, p, 0);
+		ClearSlabDebug(page);
 	}
 
 	mod_zone_page_state(page_zone(page),
@@ -1169,7 +1170,6 @@ static void discard_slab(struct kmem_cac
 
 	atomic_long_dec(&n->nr_slabs);
 	reset_page_mapcount(page);
-	ClearSlabDebug(page);
 	__ClearPageSlab(page);
 	free_slab(s, page);
 }


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