From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from westrelay02.boulder.ibm.com (westrelay02.boulder.ibm.com [9.17.195.11]) by e32.co.us.ibm.com (8.12.11.20060308/8.12.11) with ESMTP id k45Ewd46017354 for ; Fri, 5 May 2006 10:58:39 -0400 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by westrelay02.boulder.ibm.com (8.12.10/NCO/VER6.8) with ESMTP id k45EwdnG219914 for ; Fri, 5 May 2006 08:58:39 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11/8.13.3) with ESMTP id k45EwdVX004947 for ; Fri, 5 May 2006 08:58:39 -0600 Subject: Re: assert/crash in __rmqueue() when enabling CONFIG_NUMA From: Dave Hansen In-Reply-To: <20060505145018.GI19859@localhost> References: <44576688.6050607@mbligh.org> <44576BF5.8070903@yahoo.com.au> <20060504013239.GG19859@localhost> <1146756066.22503.17.camel@localhost.localdomain> <20060504154652.GA4530@localhost> <20060504192528.GA26759@elte.hu> <20060504194334.GH19859@localhost> <445A7725.8030401@shadowen.org> <20060505135503.GA5708@localhost> <1146839590.22503.48.camel@localhost.localdomain> <20060505145018.GI19859@localhost> Content-Type: text/plain Date: Fri, 05 May 2006 07:57:44 -0700 Message-Id: <1146841064.22503.53.camel@localhost.localdomain> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Bob Picco Cc: Andy Whitcroft , Ingo Molnar , Nick Piggin , "Martin J. Bligh" , Andi Kleen , linux-kernel@vger.kernel.org, Andrew Morton , Linux Memory Management List-ID: On Fri, 2006-05-05 at 10:50 -0400, Bob Picco wrote: > Dave Hansen wrote: [Fri May 05 2006, 10:33:10AM EDT] > > The page_zonenum() checks look good, but I'm not sure I understand the > > page_in_zone_hole() part. If a page is in a hole in a zone, it will > > still have a valid mem_map entry, right? It should also never have been > > put into the allocator, so it also won't ever be coalesced. > This has always been subtle and not too revealing. It probably should > have a comment. The page_in_zone_hole check is for ia64 > VIRTUAL_MEM_MAP. You might compute a page structure which is in a hole not > backed by memory; an unallocated page which covers pages structures. > VIRTUAL_MEM_MAP uses a contiguous virtual region with virtual space holes > not backed by memory. Take a look at ia64_pfn_valid. Ahhh. I hadn't made the ia64 connection. I wonder if it is worth making CONFIG_HOLES_IN_ZONE say ia64 or something about vmem_map in it somewhere. Might be worth at least a comment like this: + if (page_in_zone_hole(buddy)) /* noop on all but ia64 */ + break; + else if (page_zonenum(buddy) != page_zonenum(page)) + break; + else if (!page_is_buddy(buddy, order)) break; /* Move the buddy up one level. */ BTW, wasn't the whole idea of discontig to have holes in zones (before NUMA) without tricks like this? ;) -- Dave -- 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