From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 3B29E8D0040 for ; Thu, 24 Mar 2011 15:51:43 -0400 (EDT) Date: Thu, 24 Mar 2011 14:51:38 -0500 (CDT) From: Christoph Lameter Subject: Re: [GIT PULL] SLAB changes for v2.6.39-rc1 In-Reply-To: Message-ID: References: <1300990853.3747.189.camel@edumazet-laptop> <20110324185903.GA30510@elte.hu> <20110324193647.GA7957@elte.hu> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Pekka Enberg Cc: Ingo Molnar , Eric Dumazet , torvalds@linux-foundation.org, akpm@linux-foundation.org, tj@kernel.org, npiggin@kernel.dk, rientjes@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org On Thu, 24 Mar 2011, Pekka Enberg wrote: > Thanks, Ingo! Christoph, may I have your sign-off for the patch and > I'll send it to Linus? Subject: SLUB: Write to per cpu data when allocating it It turns out that the cmpxchg16b emulation has to access vmalloced percpu memory with interrupts disabled. If the memory has never been touched before then the fault necessary to establish the mapping will not to occur and the kernel will fail on boot. Fix that by reusing the CONFIG_PREEMPT code that writes the cpu number into a field on every cpu. Writing to the per cpu area before causes the mapping to be established before we get to a cmpxchg16b emulation. Tested-by: Ingo Molnar Signed-off-by: Christoph Lameter --- 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 2011-03-24 14:03:10.000000000 -0500 +++ linux-2.6/mm/slub.c 2011-03-24 14:04:08.000000000 -0500 @@ -1604,7 +1604,7 @@ static inline void note_cmpxchg_failure( void init_kmem_cache_cpus(struct kmem_cache *s) { -#if defined(CONFIG_CMPXCHG_LOCAL) && defined(CONFIG_PREEMPT) +#ifdef CONFIG_CMPXCHG_LOCAL int cpu; for_each_possible_cpu(cpu) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org