INFO: task hung in vcs_open (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3f8a27f9e27b Linux 4.19.211
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1129efd2880000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9277b418617afe
dashboard link: https://syzkaller.appspot.com/bug?extid=a98bd480afce0667da5c
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/98c0bdb4abb3/disk-3f8a27f9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ea228ff02669/vmlinux-3f8a27f9.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a98bd4...@syzkaller.appspotmail.com

Bluetooth: hci8: command 0x0409 tx timeout
Bluetooth: hci7: command 0x0419 tx timeout
Bluetooth: hci8: command 0x041b tx timeout
Bluetooth: hci8: command 0x040f tx timeout
Bluetooth: hci8: command 0x0419 tx timeout
INFO: task syz-executor.3:22398 blocked for more than 140 seconds.
Not tainted 4.19.211-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
syz-executor.3 D27200 22398 8118 0x00000004
Call Trace:
context_switch kernel/sched/core.c:2828 [inline]
__schedule+0x887/0x2040 kernel/sched/core.c:3517
schedule+0x8d/0x1b0 kernel/sched/core.c:3561
schedule_timeout+0x92d/0xfe0 kernel/time/timer.c:1794
__down_common kernel/locking/semaphore.c:221 [inline]
__down+0x183/0x2a0 kernel/locking/semaphore.c:238
down+0x57/0x80 kernel/locking/semaphore.c:62
console_lock+0x25/0x80 kernel/printk/printk.c:2275
vcs_open+0x62/0xc0 drivers/tty/vt/vc_screen.c:660
chrdev_open+0x266/0x770 fs/char_dev.c:423
do_dentry_open+0x4aa/0x1160 fs/open.c:796
do_last fs/namei.c:3421 [inline]
path_openat+0x793/0x2df0 fs/namei.c:3537
do_filp_open+0x18c/0x3f0 fs/namei.c:3567
do_sys_open+0x3b3/0x520 fs/open.c:1085
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fc4196305f9
Code: Bad RIP value.
RSP: 002b:00007fc417fa3168 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fc419750f80 RCX: 00007fc4196305f9
RDX: 0000000000000000 RSI: 00000000200004c0 RDI: ffffffffffffff9c
RBP: 00007fc41968b7b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fffc1dd2c2f R14: 00007fc417fa3300 R15: 0000000000022000

Showing all locks held in the system:
2 locks held by systemd/1:
1 lock held by khungtaskd/1570:
#0: 000000003df43e47 (rcu_read_lock){....}, at: debug_show_all_locks+0x53/0x265 kernel/locking/lockdep.c:4441
1 lock held by systemd-journal/4688:
1 lock held by systemd-udevd/4708:
1 lock held by in:imklog/7811:
#0: 00000000d4757c51 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x26f/0x310 fs/file.c:767
3 locks held by syz-fuzzer/8082:
5 locks held by kworker/u4:10/12179:
2 locks held by kworker/u4:11/12220:
2 locks held by syz-executor.5/22374:
5 locks held by syz-executor.5/22383:
3 locks held by syz-executor.5/22897:
1 lock held by syz-executor.3/22913:
#0: 000000009bcadc30 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline]
#0: 000000009bcadc30 (rtnl_mutex){+.+.}, at: rtnl_newlink+0x7f9/0x15c0 net/core/rtnetlink.c:3097
1 lock held by syz-executor.5/23051:
#0: 000000009bcadc30 (rtnl_mutex){+.+.}, at: rtnl_lock net/core/rtnetlink.c:77 [inline]
#0: 000000009bcadc30 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x3fe/0xb80 net/core/rtnetlink.c:4779

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 1570 Comm: khungtaskd Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
nmi_cpu_backtrace.cold+0x63/0xa2 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1a6/0x1f0 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:203 [inline]
watchdog+0x991/0xe60 kernel/hung_task.c:287
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 22897 Comm: syz-executor.5 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
RIP: 0010:debug_lockdep_rcu_enabled+0x15/0xe0 kernel/rcu/update.c:253
Code: 47 00 e9 62 fe ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 c7 c0 44 e0 26 8b 53 48 ba 00 00 00 00 00 fc ff df 48 89 c1 <83> e0 07 48 c1 e9 03 83 c0 03 0f b6 14 11 38 d0 7c 08 84 d2 0f 85
RSP: 0018:ffff888096517bd8 EFLAGS: 00000092
RAX: ffffffff8b26e044 RBX: ffff8880a81ee580 RCX: ffffffff8b26e044
RDX: dffffc0000000000 RSI: 000000006ec8abcd RDI: 0000000000000086
RBP: ffff888096517f58 R08: 00000000c55e8e46 R09: 0000000000000003
R10: ffff8880a81eee80 R11: ffffffff8c66501b R12: 0000000000000f20
R13: ffff8880a81ee658 R14: 0000000000000000 R15: ffff8880a81ee580
FS: 00005555561df400(0000) GS:ffff8880ba000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9eae701320 CR3: 000000006f2bc000 CR4: 00000000003406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
rcu_read_lock include/linux/rcupdate.h:628 [inline]
cpuacct_charge+0xa5/0x350 kernel/sched/cpuacct.c:347
cgroup_account_cputime include/linux/cgroup.h:767 [inline]
update_curr+0x2ce/0x870 kernel/sched/fair.c:858
yield_task_fair+0x160/0x240 kernel/sched/fair.c:6895
do_sched_yield+0xef/0x1a0 kernel/sched/core.c:4985
yield+0xa2/0xd0 kernel/sched/core.c:5066
tasklet_kill+0x3f/0xc0 kernel/softirq.c:566
bcm_remove_op+0x84/0x2c0 net/can/bcm.c:756
bcm_release+0x260/0x950 net/can/bcm.c:1561
__sock_release+0xcd/0x2a0 net/socket.c:599
sock_close+0x15/0x20 net/socket.c:1214
__fput+0x2ce/0x890 fs/file_table.c:278
task_work_run+0x148/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:193 [inline]
exit_to_usermode_loop+0x251/0x2a0 arch/x86/entry/common.c:167
prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
do_syscall_64+0x538/0x620 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f7acb0763cb
Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44
RSP: 002b:00007fffd2f871c0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000006 RCX: 00007f7acb0763cb
RDX: 0000001b2e520000 RSI: 00007f7acae39000 RDI: 0000000000000005
RBP: 00007f7acb1e6980 R08: 0000000000000000 R09: 00000000c2ee2f26
R10: 000d423fac2c8d50 R11: 0000000000000293 R12: 000000000008fa9a
R13: 00007fffd2f872c0 R14: 00007f7acb1e5120 R15: 0000000000000032


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.