From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031622AbeBNPjc (ORCPT ); Wed, 14 Feb 2018 10:39:32 -0500 Received: from mail-pl0-f67.google.com ([209.85.160.67]:45199 "EHLO mail-pl0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031287AbeBNPj3 (ORCPT ); Wed, 14 Feb 2018 10:39:29 -0500 X-Google-Smtp-Source: AH8x226kp3emQ5MGM8RD57ACbDxmAs782fKvpi6S2E/vdIAOhjNNfmysArazrqXMF3Isky1I+JdyBKGDLPss7V45ZS4= MIME-Version: 1.0 In-Reply-To: <001a113f64ee97b27105649a7cb2@google.com> References: <001a113f64ee97b27105649a7cb2@google.com> From: Dmitry Vyukov Date: Wed, 14 Feb 2018 16:39:08 +0100 Message-ID: Subject: Re: INFO: task hung in blk_freeze_queue To: syzbot Cc: Jens Axboe , linux-block@vger.kernel.org, LKML , syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 7, 2018 at 8:46 AM, syzbot wrote: > Hello, > > syzbot hit the following crash on upstream commit > e237f98a9c134c3d600353f21e07db915516875b (Mon Feb 5 21:35:56 2018 +0000) > Merge tag 'xfs-4.16-merge-5' of > git://git.kernel.org/pub/scm/fs/xfs/xfs-linux > > So far this crash happened 2 times on upstream. > Unfortunately, I don't have any reproducer for this crash yet. > Raw console output is attached. > compiler: gcc (GCC) 7.1.1 20170620 > .config is attached. > user-space arch: i386 Looks similar to this one: #syz dup: INFO: task hung in lo_ioctl > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+2ab52b8d94df5e2eaa01@syzkaller.appspotmail.com > It will help syzbot understand when the bug is fixed. See footer for > details. > If you forward the report, please keep this part and the footer. > > Buffer I/O error on dev loop0, logical block 0, lost async page write > INFO: task syz-executor1:14117 blocked for more than 120 seconds. > Not tainted 4.15.0+ #210 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > syz-executor1 D26432 14117 4227 0x20020004 > Call Trace: > context_switch kernel/sched/core.c:2845 [inline] > __schedule+0x8eb/0x2060 kernel/sched/core.c:3421 > schedule+0xf5/0x430 kernel/sched/core.c:3480 > blk_mq_freeze_queue_wait+0x1bb/0x400 block/blk-mq.c:136 > blk_freeze_queue+0x4a/0x80 block/blk-mq.c:165 > blk_mq_freeze_queue+0x15/0x20 block/blk-mq.c:174 > loop_change_fd drivers/block/loop.c:667 [inline] > lo_ioctl+0x10ce/0x1b70 drivers/block/loop.c:1361 > lo_compat_ioctl+0xab/0x140 drivers/block/loop.c:1556 > compat_blkdev_ioctl+0x3ae/0x1840 block/compat_ioctl.c:406 > C_SYSC_ioctl fs/compat_ioctl.c:1473 [inline] > compat_SyS_ioctl+0x151/0x2a30 fs/compat_ioctl.c:1419 > do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline] > do_fast_syscall_32+0x3ee/0xfa1 arch/x86/entry/common.c:392 > entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:129 > RIP: 0023:0xf7f44c79 > RSP: 002b:00000000f774008c EFLAGS: 00000296 ORIG_RAX: 0000000000000036 > RAX: ffffffffffffffda RBX: 0000000000000013 RCX: 0000000000004c06 > RDX: 0000000000000013 RSI: 0000000000000000 RDI: 0000000000000000 > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > > Showing all locks held in the system: > 2 locks held by khungtaskd/759: > #0: (rcu_read_lock){....}, at: [<00000000b3b533f6>] > check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline] > #0: (rcu_read_lock){....}, at: [<00000000b3b533f6>] watchdog+0x1c5/0xd60 > kernel/hung_task.c:249 > #1: (tasklist_lock){.+.+}, at: [<00000000440cd9e2>] > debug_show_all_locks+0xd3/0x3d0 kernel/locking/lockdep.c:4470 > 1 lock held by rsyslogd/4029: > #0: (&f->f_pos_lock){+.+.}, at: [<000000007729bd98>] > __fdget_pos+0x12b/0x190 fs/file.c:765 > 2 locks held by getty/4151: > #0: (&tty->ldisc_sem){++++}, at: [<00000000903280c4>] > ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 > #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000fb09d1cd>] > n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 > 2 locks held by getty/4152: > #0: (&tty->ldisc_sem){++++}, at: [<00000000903280c4>] > ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 > #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000fb09d1cd>] > n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 > 2 locks held by getty/4153: > #0: (&tty->ldisc_sem){++++}, at: [<00000000903280c4>] > ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 > #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000fb09d1cd>] > n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 > 2 locks held by getty/4154: > #0: (&tty->ldisc_sem){++++}, at: [<00000000903280c4>] > ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 > #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000fb09d1cd>] > n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 > 2 locks held by getty/4155: > #0: (&tty->ldisc_sem){++++}, at: [<00000000903280c4>] > ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 > #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000fb09d1cd>] > n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 > 2 locks held by getty/4156: > #0: (&tty->ldisc_sem){++++}, at: [<00000000903280c4>] > ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 > #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000fb09d1cd>] > n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 > 2 locks held by getty/4157: > #0: (&tty->ldisc_sem){++++}, at: [<00000000903280c4>] > ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365 > #1: (&ldata->atomic_read_lock){+.+.}, at: [<00000000fb09d1cd>] > n_tty_read+0x2ef/0x1a00 drivers/tty/n_tty.c:2131 > 1 lock held by syz-executor1/14117: > #0: (&lo->lo_ctl_mutex/1){+.+.}, at: [<00000000b6589539>] > lo_ioctl+0x8b/0x1b70 drivers/block/loop.c:1355 > > ============================================= > > NMI backtrace for cpu 1 > CPU: 1 PID: 759 Comm: khungtaskd Not tainted 4.15.0+ #210 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:17 [inline] > dump_stack+0x194/0x257 lib/dump_stack.c:53 > nmi_cpu_backtrace+0x1d2/0x210 lib/nmi_backtrace.c:103 > nmi_trigger_cpumask_backtrace+0x122/0x180 lib/nmi_backtrace.c:62 > arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 > trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline] > check_hung_task kernel/hung_task.c:132 [inline] > check_hung_uninterruptible_tasks kernel/hung_task.c:190 [inline] > watchdog+0x90c/0xd60 kernel/hung_task.c:249 > kthread+0x33c/0x400 kernel/kthread.c:238 > ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:429 > Sending NMI from CPU 1 to CPUs 0: > NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0x6/0x10 > arch/x86/include/asm/irqflags.h:54 > > > --- > This bug is generated by a dumb bot. It may contain errors. > See https://goo.gl/tpsmEJ for details. > Direct all questions to syzkaller@googlegroups.com. > > syzbot will keep track of this bug report. > If you forgot to add the Reported-by tag, once the fix for this bug is > merged > into any tree, please reply to this email with: > #syz fix: exact-commit-title > To mark this as a duplicate of another syzbot report, please reply with: > #syz dup: exact-subject-of-another-report > If it's a one-off invalid bug report, please reply with: > #syz invalid > Note: if the crash happens again, it will cause creation of a new bug > report. > Note: all commands must start from beginning of the line in the email body. > > -- > You received this message because you are subscribed to the Google Groups > "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to syzkaller-bugs+unsubscribe@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/syzkaller-bugs/001a113f64ee97b27105649a7cb2%40google.com. > For more options, visit https://groups.google.com/d/optout.