From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 85EB7C43460 for ; Fri, 17 Jul 2020 23:10:29 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3EF4A2064C for ; Fri, 17 Jul 2020 23:10:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="lfiFnDf5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3EF4A2064C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=shutemov.name Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A790D8D000B; Fri, 17 Jul 2020 19:10:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A2AEC8D0003; Fri, 17 Jul 2020 19:10:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8F1C48D000B; Fri, 17 Jul 2020 19:10:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0178.hostedemail.com [216.40.44.178]) by kanga.kvack.org (Postfix) with ESMTP id 76B9A8D0003 for ; Fri, 17 Jul 2020 19:10:28 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id E196E10F67 for ; Fri, 17 Jul 2020 23:10:27 +0000 (UTC) X-FDA: 77049113694.16.birth77_50084f126f0e Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin16.hostedemail.com (Postfix) with ESMTP id A8BDB1005CFE6 for ; Fri, 17 Jul 2020 23:10:27 +0000 (UTC) X-HE-Tag: birth77_50084f126f0e X-Filterd-Recvd-Size: 5139 Received: from mail-lj1-f193.google.com (mail-lj1-f193.google.com [209.85.208.193]) by imf22.hostedemail.com (Postfix) with ESMTP for ; Fri, 17 Jul 2020 23:10:27 +0000 (UTC) Received: by mail-lj1-f193.google.com with SMTP id x9so14491420ljc.5 for ; Fri, 17 Jul 2020 16:10:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=FmUurtNr8DsvIpsatQ0QZyiVO7vjkVTvgORSNA0VraU=; b=lfiFnDf5/hcNt4iNktxDTmBsFCUZHL+MYzpIy6YNbC7QlUQM6TakFJr+XrIzoNORkW 8bmsLA3Oq27caiG0e1TMNOoCcIVS4Tb72dSY7RCl1FF7MIGsm/fFV605IUaObL4EcZt3 elb6TRQJKRqg2Fd8aruQ1TrqlQsCQXoU0U9rAQPp93E9u0boxAPvyUzHnVwSN17g/zTJ oOgAiaPAN2sfkTG6KMPsu262V+0oxoemiJMnmKXOnaRuvVOdx4wkl9qWw97Y8YLmD4Ns cDtvEaVHQiO5i4j70j5qwCqwgnFUf7Eb/04zpIMGgGROC6T30AuKqOKg2OpAY4gmSVff 7qpA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=FmUurtNr8DsvIpsatQ0QZyiVO7vjkVTvgORSNA0VraU=; b=D23IHBM0tC818L3g1FFnwcF3L2L23i69UPhujXJrpEUT4tbD1ZCMQhhQoRUStYGdKO c7QRq58D8g83pOeG9jOzWM3KazvPR9PW2eU1rEjbGzXpIDQHicEaBFuiJ+Azs4l/vSDY nEBEg7VmPcy02nUXLnYdEJLiueKxjQjpHnFPYD7yCwmYWZmaqFlG2iHbXEWsApf1ywwI yu4tsaIOyg3uqbrtRrw3vO5IFSCiRNYz7rnV01QC8L25UG/cS/2w8u+j+laM3uI+K5E/ +rehWUwZRW1yb+RpxMbdXR9HXA0uCgrobNvBwTP3hXA72ILwNTA9AbyFDkzFmQZGB6Kc DOuQ== X-Gm-Message-State: AOAM532ZRjZZrwyXUGIQ7Hh8HSntA+rt7CdyZHie0kfpXfsPlaDdUSkx ROlQkVeKrYYrPfaQBqTBzQy+0A== X-Google-Smtp-Source: ABdhPJxFWdc1CHNgacIHbLK/JJTWJWTShV9FV/auq+6FQoYOgSaMz+P+4z+UfxI/oCDgLUPopItmAA== X-Received: by 2002:a2e:3316:: with SMTP id d22mr5578396ljc.18.1595027425548; Fri, 17 Jul 2020 16:10:25 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id i8sm1880972ljg.57.2020.07.17.16.10.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 Jul 2020 16:10:24 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id EA54F10216B; Sat, 18 Jul 2020 02:10:23 +0300 (+03) Date: Sat, 18 Jul 2020 02:10:23 +0300 From: "Kirill A. Shutemov" To: syzbot Cc: akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, torvalds@linux-foundation.org, william.kucharski@oracle.com, yang.shi@linux.alibaba.com, ziy@nvidia.com Subject: Re: general protection fault in khugepaged Message-ID: <20200717231023.tawtcmpwwqi2qsni@box> References: <000000000000358aec05a9fc8aa8@google.com> <0000000000008ad07505aaaad631@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0000000000008ad07505aaaad631@google.com> X-Rspamd-Queue-Id: A8BDB1005CFE6 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 X-Bogosity: Ham, tests=bogofilter, spamicity=0.005474, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Jul 17, 2020 at 03:40:04PM -0700, syzbot wrote: > syzbot has bisected this issue to: > > commit ffe945e633b527d5a4577b42cbadec3c7cbcf096 > Author: Kirill A. Shutemov > Date: Wed Jun 3 23:00:09 2020 +0000 > > khugepaged: do not stop collapse if less than half PTEs are referenced > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17356c2f100000 > start commit: e44f65fd xen-netfront: remove redundant assignment to vari.. > git tree: net-next > final oops: https://syzkaller.appspot.com/x/report.txt?x=14b56c2f100000 > console output: https://syzkaller.appspot.com/x/log.txt?x=10b56c2f100000 > kernel config: https://syzkaller.appspot.com/x/.config?x=829871134ca5e230 > dashboard link: https://syzkaller.appspot.com/bug?extid=ed318e8b790ca72c5ad0 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=113406a7100000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=175597d3100000 > > Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com > Fixes: ffe945e633b5 ("khugepaged: do not stop collapse if less than half PTEs are referenced") > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > My guess is that anonymous VMA got replaced by file VMA under us. Could you reproduce the issue with the patch below? I have hard time triggering it myself. diff --git a/mm/khugepaged.c b/mm/khugepaged.c index b043c40a21d4..f8ec58a1e72b 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1107,6 +1107,8 @@ static void collapse_huge_page(struct mm_struct *mm, if (mm_find_pmd(mm, address) != pmd) goto out; + if (!vma->anon_vma) + dump_vma(vma); anon_vma_lock_write(vma->anon_vma); mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm, -- Kirill A. Shutemov