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=-4.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 1424EC433EA for ; Fri, 24 Jul 2020 11:13:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E4D162073E for ; Fri, 24 Jul 2020 11:13:14 +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="kAmshiES" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727908AbgGXLNN (ORCPT ); Fri, 24 Jul 2020 07:13:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44548 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726702AbgGXLNN (ORCPT ); Fri, 24 Jul 2020 07:13:13 -0400 Received: from mail-lf1-x141.google.com (mail-lf1-x141.google.com [IPv6:2a00:1450:4864:20::141]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8F3A1C0619D3 for ; Fri, 24 Jul 2020 04:13:11 -0700 (PDT) Received: by mail-lf1-x141.google.com with SMTP id m15so4320328lfp.7 for ; Fri, 24 Jul 2020 04:13:11 -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=rodNgtRmSX3QFvgp8/2GzN9KqUWo4U594tRgIyY952U=; b=kAmshiESrG9PW9Vj0BLp/nbPKo8PKi/Dt7rIvOOaHRK99EwDSUMRSUvh4KenPcF9qP b82m+lMywKAlOupfQ/m9XhZz7leZ7F1FLQiX8xaQCT1DwS8NwMPzHqhWhIT/b7BqLlmQ LHkY9cQhgHJMqr6uj7R3lT2wm+N+LUyffL2s/tlUP993D4c+o6PmjiqHZtqumOSoBCMc /dAvzXvBMcUc9WmmZmWdwHBpisZI/xnT/iYb8TRQcenWYnYxNlfGavAmHF61VdGbJ13R zh2we/Wl8nl0998qF2aHrqUjUNiPXvQ/+i9JaZbVB2bP32zHGBzaZwU7Jq/GqWpML3GQ bLkg== 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=rodNgtRmSX3QFvgp8/2GzN9KqUWo4U594tRgIyY952U=; b=HeqBCLIHn8hlh+R5Zd6PC1QE2HM9L/tZmuviPuoUMKCt11ova3XrFVwFDUpdiU2Ckv +DEkQPgxzpWrKcJiEdMosezcBKUV0rJ9fFxm4M+UHdd93VfXyIN7nB8forCrY917WfSL Wotj/W2CXIUhAeioq8YK7fBby9+pO820seUFFbKDyS0w7mWoSYXyJcYw0Rg+jqXtCUWr LxJPgd4jgRDrek5svilxgim8XYnDs9TTpSYpMH99xpCsQDFok4jyRAtX3p1hxDnENwpU 7Zg/ugDLsUcqf7T7TmncehVtvigUX0usoFTvqDEG1AW0c7ppY1l4SJQjsw9ZbK7GzlOn SPJw== X-Gm-Message-State: AOAM532j/NIUcp9tPkIgsOustCRYL2HWayUoUuWzEkZFe2VKMku8KKqP l1N5UlshN+JJTHNmza17x5Nt1w== X-Google-Smtp-Source: ABdhPJyvoCGm12FzByJM+vcza8LqeNzc3dD7BW/22NHPUnXv4xiiA6O2yJsa9n4xjV0Y8KULv+2fKQ== X-Received: by 2002:a05:6512:3583:: with SMTP id m3mr4717313lfr.146.1595589190005; Fri, 24 Jul 2020 04:13:10 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id o68sm182612lff.57.2020.07.24.04.13.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 24 Jul 2020 04:13:09 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 4ACDA101670; Fri, 24 Jul 2020 14:13:11 +0300 (+03) Date: Fri, 24 Jul 2020 14:13:11 +0300 From: "Kirill A. Shutemov" To: Hillf Danton Cc: "Kirill A. Shutemov" , Andrew Morton , syzbot , linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, Mike Kravetz , Johannes Weiner , Jens Axboe , Markus Elfring Subject: Re: kernel BUG at include/linux/swapops.h:LINE! Message-ID: <20200724111311.rcjqigtjqpkenxg6@box> References: <000000000000bc4fd705a6e090e2@google.com> <0000000000004c38cd05aad1d13f@google.com> <20200720165144.93189f7825bd28e234a42cb8@linux-foundation.org> <20200723073744.5268-1-hdanton@sina.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200723073744.5268-1-hdanton@sina.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 23, 2020 at 03:37:44PM +0800, Hillf Danton wrote: > > On Tue, 21 Jul 2020 14:11:31 +0300 Kirill A. Shutemov wrote: > > On Mon, Jul 20, 2020 at 04:51:44PM -0700, Andrew Morton wrote: > > > On Sun, 19 Jul 2020 14:10:19 -0700 syzbot wrote: > > > > > > > syzbot has found a reproducer for the following issue on: > > > > > > > > HEAD commit: 4c43049f Add linux-next specific files for 20200716 > > > > git tree: linux-next > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=12c56087100000 > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=2c76d72659687242 > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=c48f34012b06c4ac67dd > > > > compiler: gcc (GCC) 10.1.0-syz 20200507 > > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1344abeb100000 > > > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > > Reported-by: syzbot+c48f34012b06c4ac67dd@syzkaller.appspotmail.com > > > > > > Thanks. > > > > > > __handle_mm_fault > > > ->pmd_migration_entry_wait > > > ->migration_entry_to_page > > > > > > stumbled onto an unlocked page. > > > > > > I don't immediately see a cause. Perhaps Matthew's "THP prep patches", > > > perhaps something else. > > > > > > Is it possible to perform a bisection? > > > > Maybe it's related to the new lock_page_async()? > > Or is there likely the window that after copy_huge_pmd() the src pmd migrate > entry is removed and the page unlocked but the dst is not? No. copy_huge_pmd() runs with exclusive mmap_lock on the source side and destination side is not running yet. -- Kirill A. Shutemov