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=-13.3 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=ham 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 6F873CA9EA0 for ; Mon, 4 Nov 2019 11:33:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3CED22184C for ; Mon, 4 Nov 2019 11:33:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="sf/cUGcd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727771AbfKDLdL (ORCPT ); Mon, 4 Nov 2019 06:33:11 -0500 Received: from mail-ot1-f67.google.com ([209.85.210.67]:46756 "EHLO mail-ot1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727236AbfKDLdK (ORCPT ); Mon, 4 Nov 2019 06:33:10 -0500 Received: by mail-ot1-f67.google.com with SMTP id n23so3826746otr.13 for ; Mon, 04 Nov 2019 03:33:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=3m1wIA4TogLEd7/d6SljBL6tr4IXzU8yJ7HR3M7Fnbw=; b=sf/cUGcdMUQt1h9zbB3HK/h4JkmcuPDeI7QsUB8TwmFrJ0/2hZkNVCmSspVy/TS4h1 Qn/txBgmUAGrRNIih853tomXvmCsSSyyx7t8z9CvAIrfqbx7jppYw+kBD4WUqHT65mBn T2zCLiyN0LpGjZ/9IG3EZS8CF1ZHhs3aCpi3IFmIVyNV5PVbWIahMraj9IN4MF+hx/ha oYNl5X6iqBXw3WrtjGvm/cSELuU0XxX2r6FCE9sZYmafAeLSKBXu6NtSFv7MZI6GPWN2 mczOdEN3FL2hGEiqJKR0v5pAlW76Z4u0RHtuvSKjjxuZuW3pHKWt0NzxVJE0CU1dUmdh vdHg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=3m1wIA4TogLEd7/d6SljBL6tr4IXzU8yJ7HR3M7Fnbw=; b=EJmim1omGiGS5D5NhgJJKwgoxCKGUD8p+V9K/Ib3MmTpyq9nbTQujDJO+zRylGRoab SKDlFozlf1kMBvqJQ9H5IT6L652vsbfwxWcLsNfNwfmlP9k065xM+CBYws80qGgWQRFa 9HBI9+Km/0kYVRIJNnp7iVGzx+Zxx0exP/p5Hfc+Uc5GGkt7yDR+If539HYAVdWJFKGH 2aubOJjaiLWeP2ingarEZjsH7X+VBll8uKnz3+GsxXrC+9MpBeTjKDqfdUbdnaccxZmU nEt+sN3p9+BPMD0sVd2aFRwlcoDa3abMozge5jRBNE7WahikYGUYWK83iumoQboJDgB6 O8Kg== X-Gm-Message-State: APjAAAVPkdTGbmCgXdlilkKiMHMz2xocImPng5prsDrbexM19dDUAYHE ZuClqY1GYMgAkIgC0G7DUHfBndKe/YaKOK15Kh3RQQ== X-Google-Smtp-Source: APXvYqyPczi1eyZUKIrXKTRFKN1/7adCfjT0nKKLXSm46iILcLQbwSUcGqLNmQjpdjP5ck7OC8WfWxhYohTIeFEGBbw= X-Received: by 2002:a9d:7308:: with SMTP id e8mr573623otk.17.1572867189226; Mon, 04 Nov 2019 03:33:09 -0800 (PST) MIME-Version: 1.0 References: <000000000000411e4b059683a39c@google.com> In-Reply-To: <000000000000411e4b059683a39c@google.com> From: Marco Elver Date: Mon, 4 Nov 2019 12:32:57 +0100 Message-ID: Subject: Re: KCSAN: data-race in __rcu_read_unlock / sync_rcu_exp_select_cpus To: syzbot , Lai Jiangshan , "Paul E. McKenney" , Josh Triplett , rcu@vger.kernel.org Cc: Andrew Morton , amir73il@gmail.com, darrick.wong@oracle.com, Johannes Weiner , jack@suse.cz, josef@toxicpanda.com, LKML , Linux Memory Management List , songliubraving@fb.com, syzkaller-bugs@googlegroups.com, willy@infradead.org Content-Type: text/plain; charset="UTF-8" Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org +RCU folks On Mon, 4 Nov 2019 at 12:30, syzbot wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: 05f22368 x86, kcsan: Enable KCSAN for x86 > git tree: https://github.com/google/ktsan.git kcsan > console output: https://syzkaller.appspot.com/x/log.txt?x=1296ff50e00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=87d111955f40591f > dashboard link: https://syzkaller.appspot.com/bug?extid=99f4ddade3c22ab0cf23 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+99f4ddade3c22ab0cf23@syzkaller.appspotmail.com > > ================================================================== > BUG: KCSAN: data-race in __rcu_read_unlock / sync_rcu_exp_select_cpus > > read to 0xffffffff85a7d440 of 8 bytes by task 7624 on cpu 0: > rcu_read_unlock_special kernel/rcu/tree_plugin.h:615 [inline] > __rcu_read_unlock+0x381/0x3c0 kernel/rcu/tree_plugin.h:383 > rcu_read_unlock include/linux/rcupdate.h:652 [inline] > filemap_map_pages+0x5b3/0x990 mm/filemap.c:2687 > do_fault_around mm/memory.c:3450 [inline] > do_read_fault mm/memory.c:3484 [inline] > do_fault mm/memory.c:3618 [inline] > handle_pte_fault mm/memory.c:3849 [inline] > __handle_mm_fault+0x2554/0x2cb0 mm/memory.c:3973 > handle_mm_fault+0x21b/0x530 mm/memory.c:4010 > do_user_addr_fault arch/x86/mm/fault.c:1441 [inline] > __do_page_fault+0x3fb/0x9e0 arch/x86/mm/fault.c:1506 > do_page_fault+0x54/0x233 arch/x86/mm/fault.c:1530 > page_fault+0x34/0x40 arch/x86/entry/entry_64.S:1202 > > write to 0xffffffff85a7d440 of 8 bytes by task 7353 on cpu 1: > sync_exp_reset_tree kernel/rcu/tree_exp.h:137 [inline] > sync_rcu_exp_select_cpus+0xd5/0x590 kernel/rcu/tree_exp.h:427 > rcu_exp_sel_wait_wake kernel/rcu/tree_exp.h:575 [inline] > wait_rcu_exp_gp+0x25/0x40 kernel/rcu/tree_exp.h:589 > process_one_work+0x3d4/0x890 kernel/workqueue.c:2269 > worker_thread+0xa0/0x800 kernel/workqueue.c:2415 > kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352 > > Reported by Kernel Concurrency Sanitizer on: > CPU: 1 PID: 7353 Comm: kworker/1:0 Not tainted 5.4.0-rc3+ #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Workqueue: rcu_gp wait_rcu_exp_gp > ================================================================== > Kernel panic - not syncing: panic_on_warn set ... > CPU: 1 PID: 7353 Comm: kworker/1:0 Not tainted 5.4.0-rc3+ #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Workqueue: rcu_gp wait_rcu_exp_gp > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0xf5/0x159 lib/dump_stack.c:113 > panic+0x210/0x640 kernel/panic.c:221 > kcsan_report.cold+0xc/0x10 kernel/kcsan/report.c:302 > __kcsan_setup_watchpoint+0x32e/0x4a0 kernel/kcsan/core.c:411 > __tsan_write8 kernel/kcsan/kcsan.c:36 [inline] > __tsan_write8+0x32/0x40 kernel/kcsan/kcsan.c:36 > sync_exp_reset_tree kernel/rcu/tree_exp.h:137 [inline] > sync_rcu_exp_select_cpus+0xd5/0x590 kernel/rcu/tree_exp.h:427 > rcu_exp_sel_wait_wake kernel/rcu/tree_exp.h:575 [inline] > wait_rcu_exp_gp+0x25/0x40 kernel/rcu/tree_exp.h:589 > process_one_work+0x3d4/0x890 kernel/workqueue.c:2269 > worker_thread+0xa0/0x800 kernel/workqueue.c:2415 > kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352 > Shutting down cpus with NMI > Kernel Offset: disabled > Rebooting in 86400 seconds.. > > > --- > This bug is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.