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=-5.4 required=3.0 tests=FROM_LOCAL_HEX, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS 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 A7695C43603 for ; Sat, 7 Dec 2019 17:25:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 78B0724670 for ; Sat, 7 Dec 2019 17:25:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726562AbfLGRZK (ORCPT ); Sat, 7 Dec 2019 12:25:10 -0500 Received: from mail-il1-f199.google.com ([209.85.166.199]:46328 "EHLO mail-il1-f199.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726420AbfLGRZK (ORCPT ); Sat, 7 Dec 2019 12:25:10 -0500 Received: by mail-il1-f199.google.com with SMTP id s85so7965256ild.13 for ; Sat, 07 Dec 2019 09:25:09 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:date:message-id:subject:from:to; bh=xLP8G6QTOrxF3cZLHOdxhoMT8wRTn4AVg54Rs59OOgA=; b=SiJGncozKHB2WPgtHKP3y4oUy6GLMGipuweh1ULTtffO6tlp8RAXfPx7M85cwqcXgB JcEfvSYQztyrxE0RH7Y7JHALXFM3KO8r43kXwlZdNq3T4XA+Z+U6DiJEGehA/9d2kUAT rJWRWUgePNO0m/8J2UJ5DwV84xji4EbTV2158eiw+T9rM+QvH+KRMqepAAjiDKOF2Z0k nGYmu/ybIYlz9RScybd0WU10ULk3QaeHxGJqotVc5RiZjHZ5LJq8CRCZlmRup7aN2alY 3XSiB58EyT5pnPnW2LPKD0u7HPVy6O9iVh/PaWDi3Z0fvVEqi3DD9guHpR+VINHPdTxh svug== X-Gm-Message-State: APjAAAWgMqi9V7jDmyEqWui0XEQPYvr1kkwYSuaSwhBtPirGObGpmB+5 cUOTOxcQtRlhMFgvkMxXrN/POT97JdxdqMpsBPfaoiTKuRMT X-Google-Smtp-Source: APXvYqwzUsYz2Re0zEZVbYDepM9BU5SDYtYC0J8qOECtKuSF6N2vzvRUL6ApetrDkf5817zfmQUBBSS0+kNsV+Mkiey9ItcTvz81 MIME-Version: 1.0 X-Received: by 2002:a92:45d2:: with SMTP id z79mr20306288ilj.76.1575739509264; Sat, 07 Dec 2019 09:25:09 -0800 (PST) Date: Sat, 07 Dec 2019 09:25:09 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000b55d8805992071b5@google.com> Subject: INFO: task hung in tty_ldisc_hangup From: syzbot To: gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, syzbot found the following crash on: HEAD commit: 7ada90eb Merge tag 'drm-next-2019-12-06' of git://anongit... git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=13725446e00000 kernel config: https://syzkaller.appspot.com/x/.config?x=f07a23020fd7d21a dashboard link: https://syzkaller.appspot.com/bug?extid=3105793febc8f3e591ce compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=118ae77ae00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=142ffc32e00000 Bisection is inconclusive: the bug happens on the oldest tested release. bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=120c41dae00000 console output: https://syzkaller.appspot.com/x/log.txt?x=160c41dae00000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+3105793febc8f3e591ce@syzkaller.appspotmail.com INFO: task login:10239 blocked for more than 143 seconds. Not tainted 5.4.0-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. login D27648 10239 1 0x80000002 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x934/0x1f90 kernel/sched/core.c:4081 schedule+0xdc/0x2b0 kernel/sched/core.c:4155 schedule_timeout+0x717/0xc50 kernel/time/timer.c:1871 down_write_failed drivers/tty/tty_ldsem.c:262 [inline] __ldsem_down_write_nested+0x3b2/0x8f0 drivers/tty/tty_ldsem.c:324 ldsem_down_write+0x33/0x40 drivers/tty/tty_ldsem.c:366 __tty_ldisc_lock drivers/tty/tty_ldisc.c:315 [inline] tty_ldisc_lock+0x66/0xb0 drivers/tty/tty_ldisc.c:339 tty_ldisc_hangup+0x1c6/0x640 drivers/tty/tty_ldisc.c:745 __tty_hangup.part.0+0x2fb/0x750 drivers/tty/tty_io.c:625 __tty_hangup drivers/tty/tty_io.c:575 [inline] tty_vhangup_session+0x25/0x30 drivers/tty/tty_io.c:735 disassociate_ctty.part.0+0xb4/0x740 drivers/tty/tty_jobctrl.c:267 disassociate_ctty+0x81/0xa0 drivers/tty/tty_jobctrl.c:261 do_exit+0x1b42/0x2ef0 kernel/exit.c:795 do_group_exit+0x135/0x360 kernel/exit.c:895 __do_sys_exit_group kernel/exit.c:906 [inline] __se_sys_exit_group kernel/exit.c:904 [inline] __x64_sys_exit_group+0x44/0x50 kernel/exit.c:904 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f0f83c781e8 Code: Bad RIP value. RSP: 002b:00007ffd44a828e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f0f83c781e8 RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000 RBP: 00007f0f83f4d840 R08: 00000000000000e7 R09: ffffffffffffffa8 R10: 00007f0f83f53740 R11: 0000000000000246 R12: 00007f0f83f4d840 R13: 0000000000000001 R14: 0000000000000001 R15: 000000000060b798 Showing all locks held in the system: 1 lock held by khungtaskd/1104: #0: ffffffff899a4280 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334 1 lock held by rsyslogd/9591: #0: ffff888098116b60 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 2 locks held by getty/9714: #0: ffff88808ec58090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900018e32e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9715: #0: ffff8880a7428090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900019632e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9716: #0: ffff8880a8e92090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900019032e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9717: #0: ffff888093f73090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900019532e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9718: #0: ffff888098ddf090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900019432e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9719: #0: ffff8880a72d4090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900018a32e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by login/10239: #0: ffff88809b2d2198 (&tty->legacy_mutex){+.+.}, at: tty_lock+0xc7/0x130 drivers/tty/tty_mutex.c:19 #1: ffff88809b2d2090 (&tty->ldisc_sem){++++}, at: ldsem_down_write+0x33/0x40 drivers/tty/tty_ldsem.c:366 2 locks held by syz-executor540/10274: ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1104 Comm: khungtaskd Not tainted 5.4.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x23b/0x28b 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:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xb11/0x10c0 kernel/hung_task.c:289 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 10274 Comm: syz-executor540 Not tainted 5.4.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:preempt_count_add+0x22/0x160 kernel/sched/core.c:3779 Code: 0f 1f 84 00 00 00 00 00 48 c7 c0 e0 24 63 8b 55 48 ba 00 00 00 00 00 fc ff df 48 89 c1 48 89 e5 41 54 83 e0 07 48 c1 e9 03 53 <83> c0 03 89 fb 0f b6 14 11 38 d0 7c 08 84 d2 0f 85 00 01 00 00 8b RSP: 0018:ffffc90003247628 EFLAGS: 00000806 RAX: 0000000000000000 RBX: ffffc900032476a8 RCX: 1ffffffff16c649c RDX: dffffc0000000000 RSI: 0000000000000004 RDI: 0000000000000001 RBP: ffffc90003247638 R08: 1ffff11015d07044 R09: ffffed1015d07045 R10: ffffed1015d07044 R11: ffff8880ae838223 R12: ffff8880ae837400 R13: ffffffff899c3620 R14: ffff8880906b4180 R15: 000000000000106e FS: 0000000001203880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 0000000097677000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_lockdep_current_cpu_online kernel/rcu/tree.c:969 [inline] rcu_lockdep_current_cpu_online+0x34/0x130 kernel/rcu/tree.c:961 rcu_read_lock_held_common kernel/rcu/update.c:109 [inline] rcu_read_lock_held_common+0xbd/0x130 kernel/rcu/update.c:99 rcu_read_lock_held+0x5b/0xb0 kernel/rcu/update.c:281 task_css_set include/linux/cgroup.h:478 [inline] task_dfl_cgroup include/linux/cgroup.h:547 [inline] cgroup_account_cputime include/linux/cgroup.h:776 [inline] update_curr+0x693/0x8d0 kernel/sched/fair.c:860 pick_next_task_fair+0x221/0xc70 kernel/sched/fair.c:6680 pick_next_task kernel/sched/core.c:3921 [inline] __schedule+0x375/0x1f90 kernel/sched/core.c:4051 schedule+0xdc/0x2b0 kernel/sched/core.c:4155 paste_selection+0x2f5/0x460 drivers/tty/vt/selection.c:367 tioclinux+0x133/0x480 drivers/tty/vt/vt.c:3044 vt_ioctl+0x1a41/0x26d0 drivers/tty/vt/vt_ioctl.c:364 tty_ioctl+0xa37/0x14f0 drivers/tty/tty_io.c:2660 vfs_ioctl fs/ioctl.c:47 [inline] file_ioctl fs/ioctl.c:545 [inline] do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732 ksys_ioctl+0xab/0xd0 fs/ioctl.c:749 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x441219 Code: e8 3c ad 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 9b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fffbf09e3f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441219 RDX: 00000000200000c0 RSI: 000000000000541c RDI: 0000000000000004 RBP: 000000000008ba8c R08: 000000000000000d R09: 00000000004002c8 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000402040 R13: 00000000004020d0 R14: 0000000000000000 R15: 0000000000000000 --- 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. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches