INFO: task hung in vcs_open

Status: upstream: reported on 2026/09/01 17:44
Reported-by: syzbot+2b52a05fa23d000a2f1d@syzkaller.appspotmail.com
First crash: 53d, last: 3d23h
▶ ▼ Similar bugs (14)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in vcs_open (5) serial 1 2 1329d 1333d 0/29 auto-obsoleted due to no activity on 2023/06/04 04:45
upstream INFO: task hung in vcs_open (9) kernel 1 11 530d 696d 0/29 auto-obsoleted due to no activity on 2025/08/10 23:55
upstream INFO: task hung in vcs_open (3) serial 1 1 2071d 2071d 0/29 auto-closed as invalid on 2021/05/22 19:06
upstream INFO: task hung in vcs_open serial 1 32 2242d 2375d 0/29 closed as dup on 2020/08/05 10:53
upstream INFO: task hung in vcs_open (2) serial 1 1 2222d 2222d 0/29 auto-closed as invalid on 2020/12/23 12:34
upstream INFO: task hung in vcs_open (7) serial 1 1 952d 952d 0/29 auto-obsoleted due to no activity on 2024/06/15 13:53
linux-5.15 INFO: task hung in vcs_open 1 8 46d 82d 0/3 upstream: reported on 2026/08/03 15:31
linux-4.19 INFO: task hung in vcs_open 1 11 2178d 2491d 0/1 auto-closed as invalid on 2021/03/07 01:31
upstream INFO: task hung in vcs_open (10) prio:low kernel 1 83 60d 148d 0/29 upstream: reported on 2026/05/29 18:45
upstream INFO: task hung in vcs_open (4) serial 1 2 1483d 1545d 0/29 auto-obsoleted due to no activity on 2023/01/02 16:56
linux-4.14 INFO: task hung in vcs_open 1 3 2336d 2419d 0/1 auto-closed as invalid on 2020/09/30 10:12
upstream INFO: task hung in vcs_open (6) serial 1 2 1102d 1166d 0/29 auto-obsoleted due to no activity on 2024/01/17 08:03
linux-4.19 INFO: task hung in vcs_open (2) 1 1 1461d 1461d 0/1 auto-obsoleted due to no activity on 2023/02/22 05:12
upstream INFO: task hung in vcs_open (8) nilfs serial 1 syz, C inconclusive 7 752d 758d 28/29 fixed on 2024/11/12 23:31

Sample crash report:
INFO: task syz.2.1032:9044 blocked for more than 147 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.1032      state:D stack:27888 pid:9044  ppid:8247   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5246 [inline]
 __schedule+0x107f/0x4030 kernel/sched/core.c:6563
 schedule+0xb9/0x180 kernel/sched/core.c:6639
 schedule_timeout+0xbd/0x2d0 kernel/time/timer.c:2144
 ___down_common kernel/locking/semaphore.c:229 [inline]
 __down_common+0x30c/0x740 kernel/locking/semaphore.c:250
 down+0x7c/0xd0 kernel/locking/semaphore.c:64
 console_lock+0x141/0x1c0 kernel/printk/printk.c:2629
 vcs_open+0x59/0xc0 drivers/tty/vt/vc_screen.c:763
 chrdev_open+0x585/0x5f0 fs/char_dev.c:414
 do_dentry_open+0x7dd/0x10b0 fs/open.c:882
 do_open fs/namei.c:3677 [inline]
 path_openat+0x2674/0x2f10 fs/namei.c:3834
 do_filp_open+0x1ee/0x420 fs/namei.c:3861
 do_sys_openat2+0x14b/0x4f0 fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_openat fs/open.c:1352 [inline]
 __se_sys_openat fs/open.c:1347 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1347
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd42ad9f559
RSP: 002b:00007fd428ff6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fd42b025fa0 RCX: 00007fd42ad9f559
RDX: 0000000000080300 RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007fd42ae36b20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd42b026038 R14: 00007fd42b025fa0 R15: 00007ffc5b7c45d8
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8d92e230 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8d92ea50 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x33/0xef0 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffffffff8d92d8a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8d92d8a0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8d92d8a0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6669
1 lock held by dhcpcd/3931:
 #0: ffffffff8eb566e8 (rtnl_mutex){+.+.}-{3:3}, at: __netlink_dump_start+0x11e/0x6f0 net/netlink/af_netlink.c:2310
2 locks held by getty/4026:
 #0: ffff88814d7bb098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000327b2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x41e/0x1360 drivers/tty/n_tty.c:2198
3 locks held by kworker/u4:8/4393:
 #0: ffff888018479138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #1: ffffc900042a7d00 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7b4/0x1160 kernel/workqueue.c:2267
 #2: ffffffff8eb566e8 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:263
5 locks held by syz.6.608/7157:
2 locks held by kworker/u4:13/10280:
2 locks held by kworker/u4:21/10293:
1 lock held by syz.5.1305/10378:
1 lock held by syz.4.1314/10408:
 #0: ffffffff8eb566e8 (rtnl_mutex){+.+.}-{3:3}, at: __tun_chr_ioctl+0x3f3/0x1ed0 drivers/net/tun.c:3118
1 lock held by syz.4.1314/10416:
 #0: ffffffff8eb566e8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8eb566e8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x80d/0xfb0 net/core/rtnetlink.c:6163
2 locks held by syz.1.1317/10425:
 #0: ffff8880742cb210 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:764 [inline]
 #0: ffff8880742cb210 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: __sock_release net/socket.c:653 [inline]
 #0: ffff8880742cb210 (&sb->s_type->i_mutex_key#11){+.+.}-{3:3}, at: sock_close+0x82/0x210 net/socket.c:1400
 #1: ffffffff8eb566e8 (rtnl_mutex){+.+.}-{3:3}, at: raw_release+0x1dc/0x920 net/can/raw.c:402
2 locks held by syz.1.1317/10427:
 #0: ffffffff8eb3c568 (vlan_ioctl_mutex){+.+.}-{3:3}, at: sock_ioctl+0x21b/0x700 net/socket.c:1283
 #1: ffffffff8eb566e8 (rtnl_mutex){+.+.}-{3:3}, at: vlan_ioctl_handler+0xef/0x5c0 net/8021q/vlan.c:580
1 lock held by syz.0.1326/10461:
 #0: ffffffff8eb566e8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8eb566e8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x80d/0xfb0 net/core/rtnetlink.c:6163
2 locks held by syz.3.1338/10490:

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

NMI backtrace for cpu 0
CPU: 0 PID: 28 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3e6/0x460 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1d4/0x450 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf0e/0xf50 kernel/hung_task.c:377
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/21 14:44 linux-6.1.y 79807e970724 61c200c7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in vcs_open
2026/10/12 12:07 linux-6.1.y a500ba24937a 4f92358f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in vcs_open
2026/09/01 17:44 linux-6.1.y d64a499eea6b 587f6b29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in vcs_open
* Struck through repros no longer work on HEAD.