Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751200AbWHPPAK (ORCPT ); Wed, 16 Aug 2006 11:00:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751208AbWHPPAJ (ORCPT ); Wed, 16 Aug 2006 11:00:09 -0400 Received: from e3.ny.us.ibm.com ([32.97.182.143]:16365 "EHLO e3.ny.us.ibm.com") by vger.kernel.org with ESMTP id S1751200AbWHPPAI (ORCPT ); Wed, 16 Aug 2006 11:00:08 -0400 Subject: Re: 2.6.18-rc3->rc4 hugetlbfs regression From: Adam Litke To: Dave Hansen Cc: Linux Kernel Mailing List , linux-mm , Yao Fei Zhu , Suzuki Kp , Nishanth Aravamudan , lge@us.ibm.com, PPC External List , "ADAM G. LITKE [imap]" In-Reply-To: <1155655344.12700.45.camel@localhost.localdomain> References: <1155655344.12700.45.camel@localhost.localdomain> Content-Type: text/plain Date: Wed, 16 Aug 2006 10:00:04 -0500 Message-Id: <1155740404.21863.70.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2157 Lines: 55 On Tue, 2006-08-15 at 08:22 -0700, Dave Hansen wrote: > kernel BUG in cache_free_debugcheck at mm/slab.c:2748! Alright, this one is only triggered when slab debugging is enabled. The slabs are assumed to be aligned on a HUGEPTE_TABLE_SIZE boundary. The free path makes use of this assumption and uses the lowest nibble to pass around an index into an array of kmem_cache pointers. With slab debugging turned on, the slab is still aligned, but the "working" object pointer is not. This would break the assumption above that a full nibble is available for the PGF_CACHENUM_MASK. The following patch reduces PGF_CACHENUM_MASK to cover only the two least significant bits, which is enough to cover the current number of 4 pgtable cache types. Then use this constant to mask out the appropriate part of the huge pte pointer. Signed-off-by: Adam Litke --- arch/powerpc/mm/hugetlbpage.c | 2 +- include/asm-powerpc/pgalloc.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff -upN reference/arch/powerpc/mm/hugetlbpage.c current/arch/powerpc/mm/hugetlbpage.c --- reference/arch/powerpc/mm/hugetlbpage.c +++ current/arch/powerpc/mm/hugetlbpage.c @@ -153,7 +153,7 @@ static void free_hugepte_range(struct mm hpdp->pd = 0; tlb->need_flush = 1; pgtable_free_tlb(tlb, pgtable_free_cache(hugepte, HUGEPTE_CACHE_NUM, - HUGEPTE_TABLE_SIZE-1)); + PGF_CACHENUM_MASK)); } #ifdef CONFIG_PPC_64K_PAGES diff -upN reference/include/asm-powerpc/pgalloc.h current/include/asm-powerpc/pgalloc.h --- reference/include/asm-powerpc/pgalloc.h +++ current/include/asm-powerpc/pgalloc.h @@ -117,7 +117,7 @@ static inline void pte_free(struct page pte_free_kernel(page_address(ptepage)); } -#define PGF_CACHENUM_MASK 0xf +#define PGF_CACHENUM_MASK 0x3 typedef struct pgtable_free { unsigned long val; -- Adam Litke - (agl at us.ibm.com) IBM Linux Technology Center - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/