Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754498AbaAaVOc (ORCPT ); Fri, 31 Jan 2014 16:14:32 -0500 Received: from www.sr71.net ([198.145.64.142]:57327 "EHLO blackbird.sr71.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754473AbaAaVOb (ORCPT ); Fri, 31 Jan 2014 16:14:31 -0500 Message-ID: <52EC1235.30909@sr71.net> Date: Fri, 31 Jan 2014 13:14:29 -0800 From: Dave Hansen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Petr Tesarik , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org CC: Jiang Liu , Andrew Morton , Dave Hansen , linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86: fix the initialization of physnode_map References: <20140131110517.4b7e86d6@hananiah.suse.cz> In-Reply-To: <20140131110517.4b7e86d6@hananiah.suse.cz> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/31/2014 02:05 AM, Petr Tesarik wrote: > With DISCONTIGMEM, the mapping between a pfn and its owning node is > initialized using data provided by the BIOS or from the command line. > However, the initialization may fail if the extents are not aligned > to section boundary (64M). So is this a problem that shows up with DISCONTIGMEM? Just curious, but what the heck kind of 32-bit NUMA hardware is still in the wild? Did someon buy a NUMA-Q on eBay? :) > void memory_present(int nid, unsigned long start, unsigned long end) > { > - unsigned long pfn; > + unsigned long sect, endsect; > > printk(KERN_INFO "Node: %d, start_pfn: %lx, end_pfn: %lx\n", > nid, start, end); > printk(KERN_DEBUG " Setting physnode_map array to node %d for pfns:\n", nid); > printk(KERN_DEBUG " "); > - for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) { > - physnode_map[pfn / PAGES_PER_SECTION] = nid; > - printk(KERN_CONT "%lx ", pfn); > + endsect = (end - 1) / PAGES_PER_SECTION; > + for (sect = start / PAGES_PER_SECTION; sect <= endsect; ++sect) { > + physnode_map[sect] = nid; > + printk(KERN_CONT "%lx ", sect * PAGES_PER_SECTION); > } > printk(KERN_CONT "\n"); > } So, if start and end are not aligned to section boundaries, we will miss setting physnode_map[] for the final section? For instance, if we have a 64MB section size and try to call memory_present(32MB -> 96MB), we will set 0->64MB present, but not set the 64MB->128MB section as present. Right? Can you just align 'start' down to the section's start and 'end' up to the end of the section that contains it? I guess you do that implicitly, but you should be able to do it without refactoring the for loop entirely. -- 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/