From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qg0-f47.google.com (mail-qg0-f47.google.com [209.85.192.47]) by kanga.kvack.org (Postfix) with ESMTP id EBEAF6B0035 for ; Fri, 8 Aug 2014 11:55:00 -0400 (EDT) Received: by mail-qg0-f47.google.com with SMTP id i50so6061314qgf.20 for ; Fri, 08 Aug 2014 08:55:00 -0700 (PDT) Received: from qmta01.emeryville.ca.mail.comcast.net (qmta01.emeryville.ca.mail.comcast.net. [2001:558:fe2d:43:76:96:30:16]) by mx.google.com with ESMTP id x10si7144600qar.30.2014.08.08.08.54.59 for ; Fri, 08 Aug 2014 08:55:00 -0700 (PDT) Date: Fri, 8 Aug 2014 10:54:57 -0500 (CDT) From: Christoph Lameter Subject: Re: [PATCH for v3.17-rc1] Revert "slab: remove BAD_ALIEN_MAGIC" In-Reply-To: Message-ID: References: <1407481239-7572-1-git-send-email-iamjoonsoo.kim@lge.com> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Geert Uytterhoeven Cc: Joonsoo Kim , Andrew Morton , Pekka Enberg , David Rientjes , Linux MM , "linux-kernel@vger.kernel.org" , Vladimir Davydov On Fri, 8 Aug 2014, Geert Uytterhoeven wrote: > On Fri, Aug 8, 2014 at 4:44 PM, Christoph Lameter wrote: > > On Fri, 8 Aug 2014, Joonsoo Kim wrote: > > > >> This reverts commit a640616822b2 ("slab: remove BAD_ALIEN_MAGIC"). > > > > Lets hold off on this one. I am bit confused as to why a non NUMA system > > would have multiple NUMA nodes. > > DISCONTIGMEM > > mm/Kconfig: > > # > # Both the NUMA code and DISCONTIGMEM use arrays of pg_data_t's > # to represent different areas of memory. This variable allows > # those dependencies to exist individually. > # > config NEED_MULTIPLE_NODES > def_bool y > depends on DISCONTIGMEM || NUMA Uhhh... And how does one access memory when the node is != 0 given that zone_to_nid always returns 0 in the !CONFIG_NUMA case? AFAICT there are numerous of these node == 0 assumptions in the kernel for !NUMA. include/linux/mmzone.h: #ifdef CONFIG_NUMA #define pfn_to_nid(pfn) \ ({ \ unsigned long __pfn_to_nid_pfn = (pfn); \ page_to_nid(pfn_to_page(__pfn_to_nid_pfn)); \ }) #else #define pfn_to_nid(pfn) (0) #endif How can this work at all???? -- 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/ . Don't email: email@kvack.org