From patchwork Tue Oct 8 15:29:15 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 11179765 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A686C139A for ; Tue, 8 Oct 2019 15:29:33 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 73C5A21721 for ; Tue, 8 Oct 2019 15:29:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 73C5A21721 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id AC5D08E0005; Tue, 8 Oct 2019 11:29:32 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id A4ED48E0003; Tue, 8 Oct 2019 11:29:32 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9166D8E0005; Tue, 8 Oct 2019 11:29:32 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0075.hostedemail.com [216.40.44.75]) by kanga.kvack.org (Postfix) with ESMTP id 6B0AD8E0003 for ; Tue, 8 Oct 2019 11:29:32 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 12942824CA38 for ; Tue, 8 Oct 2019 15:29:32 +0000 (UTC) X-FDA: 76021001784.01.work17_532be94b0144d X-Spam-Summary: 1,0,0,,d41d8cd98f00b204,vbabka@suse.cz,:akpm@linux-foundation.org:mgorman@techsingularity.net:fw@deneb.enyo.de:david@fromorbit.com::linux-kernel@vger.kernel.org:linux-xfs@vger.kernel.org:linux-fsdevel@vger.kernel.org:vbabka@suse.cz:stable@vger.kernel.org,RULES_HIT:30012:30054:30070,0,RBL:195.135.220.15:@suse.cz:.lbl8.mailshell.net-62.2.6.2 64.100.201.201,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:25,LUA_SUMMARY:none X-HE-Tag: work17_532be94b0144d X-Filterd-Recvd-Size: 3383 Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by imf15.hostedemail.com (Postfix) with ESMTP for ; Tue, 8 Oct 2019 15:29:31 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 1D112B1B6; Tue, 8 Oct 2019 15:29:30 +0000 (UTC) From: Vlastimil Babka To: Andrew Morton , Mel Gorman , Florian Weimer , Dave Chinner Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Vlastimil Babka , stable@vger.kernel.org Subject: [PATCH] mm, compaction: fix wrong pfn handling in __reset_isolation_pfn() Date: Tue, 8 Oct 2019 17:29:15 +0200 Message-Id: <20191008152915.24704-1-vbabka@suse.cz> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Florian and Dave reported [1] a NULL pointer dereference in __reset_isolation_pfn(). While the exact cause is unclear, staring at the code revealed two bugs, which might be related. One bug is that if zone starts in the middle of pageblock, block_page might correspond to different pfn than block_pfn, and then the pfn_valid_within() checks will check different pfn's than those accessed via struct page. This might result in acessing an unitialized page in CONFIG_HOLES_IN_ZONE configs. The other bug is that end_page refers to the first page of next pageblock and not last page of current pageblock. The online and valid check is then wrong and with sections, the while (page < end_page) loop might wander off actual struct page arrays. [1] https://lore.kernel.org/linux-xfs/87o8z1fvqu.fsf@mid.deneb.enyo.de/ Reported-by: Florian Weimer Reported-by: Dave Chinner Fixes: 6b0868c820ff ("mm/compaction.c: correct zone boundary handling when resetting pageblock skip hints") Cc: Signed-off-by: Vlastimil Babka Acked-by: Mel Gorman --- mm/compaction.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index ce08b39d85d4..672d3c78c6ab 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -270,14 +270,15 @@ __reset_isolation_pfn(struct zone *zone, unsigned long pfn, bool check_source, /* Ensure the start of the pageblock or zone is online and valid */ block_pfn = pageblock_start_pfn(pfn); - block_page = pfn_to_online_page(max(block_pfn, zone->zone_start_pfn)); + block_pfn = max(block_pfn, zone->zone_start_pfn); + block_page = pfn_to_online_page(block_pfn); if (block_page) { page = block_page; pfn = block_pfn; } /* Ensure the end of the pageblock or zone is online and valid */ - block_pfn += pageblock_nr_pages; + block_pfn = pageblock_end_pfn(pfn) - 1; block_pfn = min(block_pfn, zone_end_pfn(zone) - 1); end_page = pfn_to_online_page(block_pfn); if (!end_page) @@ -303,7 +304,7 @@ __reset_isolation_pfn(struct zone *zone, unsigned long pfn, bool check_source, page += (1 << PAGE_ALLOC_COSTLY_ORDER); pfn += (1 << PAGE_ALLOC_COSTLY_ORDER); - } while (page < end_page); + } while (page <= end_page); return false; }