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 986A5C43603 for ; Sun, 15 Dec 2019 19:15:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4B50624679 for ; Sun, 15 Dec 2019 19:15:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726422AbfLOTPK (ORCPT ); Sun, 15 Dec 2019 14:15:10 -0500 Received: from mail-io1-f71.google.com ([209.85.166.71]:33893 "EHLO mail-io1-f71.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726232AbfLOTPK (ORCPT ); Sun, 15 Dec 2019 14:15:10 -0500 Received: by mail-io1-f71.google.com with SMTP id n26so4263545ioj.1 for ; Sun, 15 Dec 2019 11:15:09 -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:in-reply-to:message-id:subject :from:to; bh=/iZ4DjVWr9dBOt5+in3+RlcgccpjJAymn5wYhNeLHy4=; b=HGVJpJvXeHbL7+rVItD4dihCM8geFJ65G59/XoS6dJuYGFfQXNx1pWulgXUD7yu6T5 R8tovxJxBS08opzMFbUCF/4oFwJ1EIobIhrwVyzz7EDIOOA+kcHMMz5mKUZ51senIDGD +n1CUsV61XD86NX40p/sSsbT8fnJG7gocSdwCjLAyhJ86wsS7RBSPDdVK+CBYoqWFTbC PVlkrpAFLRvxIFrawVhUd1gS2kO+3Z5Pd0C+i2TM+C2mAgQPsoqbCUUlolJbezTA/rHX wJtFgX2aN60yZwrHg8GJ0V9hYMgrq62ZNBh0o/jPIbkUoKl7WeUE424CU5WX45vI+7Vn 6lhQ== X-Gm-Message-State: APjAAAX5lQWLsoDRfKvb8jaexwRPFeDiP5f53U1LGM0yfGYHViYnQvzT ZmOzK9PKbGU14cBuGltqSwfbZpYSYsfNOd5b4GM49IvpQgdM X-Google-Smtp-Source: APXvYqyJYzLX3aoD0COI7H1zKQpI2ZRZDuwqcU6+/El2BziY7p7nZA8p0+VwU62I2IpD4k3j9JxmGtZWHWjdjuVE/OZUfRCig028 MIME-Version: 1.0 X-Received: by 2002:a02:c787:: with SMTP id n7mr9035239jao.85.1576437308941; Sun, 15 Dec 2019 11:15:08 -0800 (PST) Date: Sun, 15 Dec 2019 11:15:08 -0800 In-Reply-To: <000000000000fe6c39059905c289@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000cf6b330599c2e996@google.com> Subject: Re: INFO: task hung in flush_to_ldisc 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 syzbot has found a reproducer for the following crash on: HEAD commit: 07c4b9e9 Merge tag 'scsi-fixes' of git://git.kernel.org/pu.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=102dafeae00000 kernel config: https://syzkaller.appspot.com/x/.config?x=79f79de2a27d3e3d dashboard link: https://syzkaller.appspot.com/bug?extid=e199b43b49192126ff69 compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11a4efdae00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11ccf946e00000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+e199b43b49192126ff69@syzkaller.appspotmail.com INFO: task kworker/u4:2:24 blocked for more than 143 seconds. Not tainted 5.5.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:2 D24104 24 2 0x80004000 Workqueue: events_unbound flush_to_ldisc 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_preempt_disabled+0x13/0x20 kernel/sched/core.c:4214 __mutex_lock_common kernel/locking/mutex.c:1036 [inline] __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1106 mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1121 flush_to_ldisc+0x3d/0x390 drivers/tty/tty_buffer.c:505 process_one_work+0x9af/0x1740 kernel/workqueue.c:2264 worker_thread+0x98/0xe40 kernel/workqueue.c:2410 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 INFO: task login:9609 blocked for more than 143 seconds. Not tainted 5.5.0-rc1-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. login D27648 9609 1 0x00000004 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 do_wait_for_common kernel/sched/completion.c:83 [inline] __wait_for_common kernel/sched/completion.c:104 [inline] wait_for_common kernel/sched/completion.c:115 [inline] wait_for_completion+0x29c/0x440 kernel/sched/completion.c:136 __flush_work+0x4fe/0xa50 kernel/workqueue.c:3041 flush_work+0x18/0x20 kernel/workqueue.c:3062 tty_buffer_flush_work+0x16/0x20 drivers/tty/tty_buffer.c:618 n_tty_read+0xaea/0x1bf0 drivers/tty/n_tty.c:2199 tty_read+0x1a0/0x2a0 drivers/tty/tty_io.c:869 __vfs_read+0x8a/0x110 fs/read_write.c:425 vfs_read+0x1f0/0x440 fs/read_write.c:461 ksys_read+0x14f/0x290 fs/read_write.c:587 __do_sys_read fs/read_write.c:597 [inline] __se_sys_read fs/read_write.c:595 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:595 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7f6202982310 Code: Bad RIP value. RSP: 002b:00007ffe08871a88 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f6202982310 RDX: 00000000000001ff RSI: 00007ffe08871cf0 RDI: 0000000000000000 RBP: 0000000000000000 R08: 00007f6203265700 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe08871cf0 R13: 0000000000000000 R14: 0000000000000001 R15: 000000000060b798 Showing all locks held in the system: 3 locks held by kworker/u4:2/24: #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: __write_once_size include/linux/compiler.h:226 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:855 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:40 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: set_work_data kernel/workqueue.c:615 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:642 [inline] #0: ffff8880aa433928 ((wq_completion)events_unbound){+.+.}, at: process_one_work+0x88b/0x1740 kernel/workqueue.c:2235 #1: ffffc90000e17dc0 ((work_completion)(&buf->work)){+.+.}, at: process_one_work+0x8c1/0x1740 kernel/workqueue.c:2239 #2: ffff8880aa5bc0a8 (&buf->lock){+.+.}, at: flush_to_ldisc+0x3d/0x390 drivers/tty/tty_buffer.c:505 1 lock held by khungtaskd/1112: #0: ffffffff899a56c0 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334 1 lock held by rsyslogd/9079: #0: ffff8880962650e0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:801 2 locks held by getty/9170: #0: ffff8880a7af2090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000182b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9171: #0: ffff88809ba38090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000184b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9172: #0: ffff88808fc60090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000181b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9173: #0: ffff8880928a3090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000183b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9174: #0: ffff8880a30e4090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900017eb2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9175: #0: ffff8880a79aa090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000178b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by login/9609: #0: ffff8880a2673090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000185b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 3 locks held by syz-executor065/9634: #0: ffff8880a2673090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffff8880aa5bc0a8 (&buf->lock){+.+.}, at: tty_buffer_lock_exclusive+0x30/0x40 drivers/tty/tty_buffer.c:61 #2: ffff8880ae837358 (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1215 [inline] #2: ffff8880ae837358 (&rq->lock){-.-.}, at: __schedule+0x232/0x1f90 kernel/sched/core.c:4029 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1112 Comm: khungtaskd Not tainted 5.5.0-rc1-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: 9634 Comm: syz-executor065 Not tainted 5.5.0-rc1-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__rcu_read_unlock+0x7c/0x710 kernel/rcu/tree_plugin.h:380 Code: fd ff ff 3f 41 8d 47 ff 81 f9 fd ff ff 3f 41 89 86 78 03 00 00 0f 86 ac 00 00 00 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d c3 <48> b8 00 00 00 00 00 fc ff df 4c 89 e6 48 c1 ee 03 0f b6 04 06 84 RSP: 0018:ffffc90001a976b0 EFLAGS: 00000046 RAX: 0000000000000000 RBX: ffff8880a77d04c0 RCX: 1ffff11014efa0f7 RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8880ae8381e0 RBP: ffffc90001a976f0 R08: 1ffff11015d0703c R09: ffffed1015d0703d R10: ffffed1015d0703c R11: ffff8880ae8381e3 R12: ffff8880a77d07b8 R13: ffffffff899c5cf0 R14: ffff8880a77d0440 R15: 0000000000000001 FS: 0000000001845880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000000a9307000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: rcu_read_unlock include/linux/rcupdate.h:670 [inline] cgroup_account_cputime include/linux/cgroup.h:779 [inline] update_curr+0x3e5/0x8d0 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: 0033:0x441209 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:00007ffe7c0d3a88 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000441209 RDX: 0000000020000080 RSI: 000000000000541c RDI: 0000000000000003 RBP: 00000000000808bc R08: 00000000004002c8 R09: 00000000004002c8 R10: 000000000000000d R11: 0000000000000246 R12: 0000000000402030 R13: 00000000004020c0 R14: 0000000000000000 R15: 0000000000000000