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[46.22.139.233]) by mx.google.com with ESMTPS id y46si1031844edc.298.2019.05.09.02.57.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 09 May 2019 02:57:26 -0700 (PDT) Received-SPF: pass (google.com: domain of mgorman@techsingularity.net designates 46.22.139.233 as permitted sender) client-ip=46.22.139.233; Authentication-Results: mx.google.com; spf=pass (google.com: domain of mgorman@techsingularity.net designates 46.22.139.233 as permitted sender) smtp.mailfrom=mgorman@techsingularity.net Received: from mail.blacknight.com (pemlinmail04.blacknight.ie [81.17.254.17]) by outbound-smtp16.blacknight.com (Postfix) with ESMTPS id 60DA61C299F for ; Thu, 9 May 2019 10:57:26 +0100 (IST) Received: (qmail 28448 invoked from network); 9 May 2019 09:57:26 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[37.228.225.79]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 9 May 2019 09:57:26 -0000 Date: Thu, 9 May 2019 10:57:24 +0100 From: Mel Gorman To: syzbot Cc: akpm@linux-foundation.org, aryabinin@virtuozzo.com, cai@lca.pw, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, syzkaller-bugs@googlegroups.com, vbabka@suse.cz Subject: Re: BUG: unable to handle kernel paging request in isolate_freepages_block Message-ID: <20190509095724.GG18914@techsingularity.net> References: <0000000000003beebd0588492456@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <0000000000003beebd0588492456@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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: On Tue, May 07, 2019 at 02:50:05AM -0700, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: baf76f0c slip: make slhc_free() silently accept an error p.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=16dbe6cca00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=a42d110b47dd6b36 > dashboard link: https://syzkaller.appspot.com/bug?extid=d84c80f9fe26a0f7a734 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. > How reproducible is it and can the following (compile tested only) patch be tested please? I'm thinking it's a similar class of bug to 6b0868c820ff ("mm/compaction.c: correct zone boundary handling when resetting pageblock skip hints") diff --git a/mm/compaction.c b/mm/compaction.c index 3319e0872d01..ae4d99d31b61 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1228,7 +1228,7 @@ fast_isolate_around(struct compact_control *cc, unsigned long pfn, unsigned long /* Pageblock boundaries */ start_pfn = pageblock_start_pfn(pfn); - end_pfn = min(start_pfn + pageblock_nr_pages, zone_end_pfn(cc->zone)); + end_pfn = min(start_pfn + pageblock_nr_pages, zone_end_pfn(cc->zone) - 1); /* Scan before */ if (start_pfn != pfn) { @@ -1239,7 +1239,7 @@ fast_isolate_around(struct compact_control *cc, unsigned long pfn, unsigned long /* Scan after */ start_pfn = pfn + nr_isolated; - if (start_pfn != end_pfn) + if (start_pfn < end_pfn) isolate_freepages_block(cc, &start_pfn, end_pfn, &cc->freepages, 1, false); /* Skip this pageblock in the future as it's full or nearly full */