From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx103.postini.com [74.125.245.103]) by kanga.kvack.org (Postfix) with SMTP id 1ED816B00CE for ; Thu, 6 Dec 2012 13:30:55 -0500 (EST) Received: from ipb4.telenor.se (ipb4.telenor.se [195.54.127.167]) by smtprelay-h21.telenor.se (Postfix) with ESMTP id 5FEAAE93CE for ; Thu, 6 Dec 2012 19:30:53 +0100 (CET) From: "Henrik Rydberg" Date: Thu, 6 Dec 2012 19:32:59 +0100 Subject: Re: Oops in 3.7-rc8 isolate_free_pages_block() Message-ID: <20121206183259.GA591@polaris.bitmath.org> References: <20121206091744.GA1397@polaris.bitmath.org> <20121206144821.GC18547@quack.suse.cz> <20121206161934.GA17258@suse.de> <20121206175451.GC17258@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Linus Torvalds Cc: Mel Gorman , Jan Kara , linux-mm , Linux Kernel Mailing List On Thu, Dec 06, 2012 at 10:19:35AM -0800, Linus Torvalds wrote: > On Thu, Dec 6, 2012 at 9:55 AM, Mel Gorman wrote: > > > > Yeah. I was listening to a talk while I was writing it, a bit cranky and > > didn't see why I should suffer alone. > > Makes sense. > > > Quasimoto strikes again > > Is that Quasimodo's Japanese cousin? > > > - end_pfn = min(pfn + pageblock_nr_pages, zone_end_pfn); > > + > > + /* > > + * As pfn may not start aligned, pfn+pageblock_nr_page > > + * may cross a MAX_ORDER_NR_PAGES boundary and miss > > + * a pfn_valid check. Ensure isolate_freepages_block() > > + * only scans within a pageblock. > > + */ > > + end_pfn = ALIGN(pfn + pageblock_nr_pages, pageblock_nr_pages); > > + end_pfn = min(end_pfn, end_pfn); > > Ok, this looks much nicer, except it's obviously buggy. The > min(end_pfn, end_pfn) thing is insane, and I'm sure you meant for that > line to be > > + end_pfn = min(end_pfn, zone_end_pfn); > > Henrik, does that - corrected - patch (*instead* of the previous one, > not in addition to) also fix your issue? Yes - I can no longer trigger the failpath, so it seems to work. Mel, enjoy the rest of the talk. ;-) Generally, I am a bit surprised that noone hit this before, given that it was quite easy to trigger. I will check 3.6 as well. Thanks, Henrik -- 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