INFO: task syz.9.1823:14901 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.9.1823      state:D stack:27912 pid:14901 ppid:12088  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_timeout+0xc1/0x2d0 kernel/time/timer.c:2144
 ___down_common kernel/locking/semaphore.c:229 [inline]
 __down_common+0x30e/0x650 kernel/locking/semaphore.c:250
 down+0x80/0xd0 kernel/locking/semaphore.c:64
 console_lock+0x145/0x1b0 kernel/printk/printk.c:2686
 vt_resize+0x46/0xc0 drivers/tty/vt/vt.c:1332
 tiocswinsz+0xff/0x150 drivers/tty/tty_io.c:2370
 tty_ioctl+0x22a/0xdc0 drivers/tty/tty_io.c:2697
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fac6e99e159
RSP: 002b:00007fac6f8c8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fac6ec25fa0 RCX: 00007fac6e99e159
RDX: 0000200000000140 RSI: 0000000000005414 RDI: 0000000000000003
RBP: 00007fac6ea35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fac6ec26038 R14: 00007fac6ec25fa0 R15: 00007ffc956f8cd8
 </TASK>
INFO: task syz.0.1841:15021 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.1841      state:D stack:27400 pid:15021 ppid:13856  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_timeout+0xc1/0x2d0 kernel/time/timer.c:2144
 ___down_common kernel/locking/semaphore.c:229 [inline]
 __down_common+0x30e/0x650 kernel/locking/semaphore.c:250
 down+0x80/0xd0 kernel/locking/semaphore.c:64
 console_lock+0x145/0x1b0 kernel/printk/printk.c:2686
 con_install+0x98/0x720 drivers/tty/vt/vt.c:3331
 tty_driver_install_tty drivers/tty/tty_io.c:1302 [inline]
 tty_init_dev+0xd3/0x4c0 drivers/tty/tty_io.c:1414
 tty_open_by_driver drivers/tty/tty_io.c:2080 [inline]
 tty_open+0x7dd/0xcc0 drivers/tty/tty_io.c:2127
 chrdev_open+0x58c/0x600 fs/char_dev.c:414
 do_dentry_open+0x880/0x14b0 fs/open.c:929
 do_open fs/namei.c:3683 [inline]
 path_openat+0x284f/0x3270 fs/namei.c:3844
 do_filp_open+0x1f2/0x430 fs/namei.c:3871
 do_sys_openat2+0x134/0x1d0 fs/open.c:1422
 do_sys_open fs/open.c:1437 [inline]
 __do_sys_openat fs/open.c:1453 [inline]
 __se_sys_openat fs/open.c:1448 [inline]
 __x64_sys_openat+0x139/0x160 fs/open.c:1448
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f945b75e98e
RSP: 002b:00007f945c623b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f945c6246c0 RCX: 00007f945b75e98e
RDX: 0000000000000002 RSI: 00007f945c623c00 RDI: ffffffffffffff9c
RBP: 00007f945b835024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f945ba26038 R14: 00007f945ba25fa0 R15: 00007ffe4e3d27b8
 </TASK>
INFO: task syz.0.1841:15023 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.1841      state:D stack:27912 pid:15023 ppid:13856  flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x15ae/0x4660 kernel/sched/core.c:6701
 schedule+0xbd/0x170 kernel/sched/core.c:6775
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6834
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747
 tty_open_by_driver drivers/tty/tty_io.c:2044 [inline]
 tty_open+0x211/0xcc0 drivers/tty/tty_io.c:2127
 chrdev_open+0x58c/0x600 fs/char_dev.c:414
 do_dentry_open+0x880/0x14b0 fs/open.c:929
 do_open fs/namei.c:3683 [inline]
 path_openat+0x284f/0x3270 fs/namei.c:3844
 do_filp_open+0x1f2/0x430 fs/namei.c:3871
 do_sys_openat2+0x134/0x1d0 fs/open.c:1422
 do_sys_open fs/open.c:1437 [inline]
 __do_sys_openat fs/open.c:1453 [inline]
 __se_sys_openat fs/open.c:1448 [inline]
 __x64_sys_openat+0x139/0x160 fs/open.c:1448
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f945b75e98e
RSP: 002b:00007f945c602b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f945c6036c0 RCX: 00007f945b75e98e
RDX: 0000000000000002 RSI: 00007f945c602c00 RDI: ffffffffffffff9c
RBP: 00007f945b835024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f945ba26128 R14: 00007f945ba26090 R15: 00007ffe4e3d27b8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #0: ffffffff8d131da0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6633
2 locks held by kworker/u4:5/1077:
2 locks held by getty/5534:
 #0: ffff88802d4890a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000326e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x428/0x1370 drivers/tty/n_tty.c:2217
6 locks held by syz.4.1819/14884:
2 locks held by syz.0.1841/15021:
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2044 [inline]
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x211/0xcc0 drivers/tty/tty_io.c:2127
 #1: ffff8880309fc1c0 (&tty->legacy_mutex){+.+.}-{3:3}, at: tty_init_dev+0x74/0x4c0 drivers/tty/tty_io.c:1413
1 lock held by syz.0.1841/15023:
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2044 [inline]
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x211/0xcc0 drivers/tty/tty_io.c:2127
3 locks held by kworker/u4:3/15450:
 #0: ffff88802c80e138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #0: ffff88802c80e138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #1: ffffc90003737d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline]
 #1: ffffc90003737d00 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734
 #2: ffffffff8e3d6fc8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xce/0x1550 net/ipv6/addrconf.c:4188
1 lock held by syz.6.1931/15542:
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2044 [inline]
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x211/0xcc0 drivers/tty/tty_io.c:2127
1 lock held by syz.7.1943/15622:
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2044 [inline]
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x211/0xcc0 drivers/tty/tty_io.c:2127
1 lock held by syz.1.1959/15762:
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd0/0x2c0 drivers/tty/pty.c:823
1 lock held by syz.3.1977/15941:
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2044 [inline]
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x211/0xcc0 drivers/tty/tty_io.c:2127
1 lock held by syz.8.1995/16045:
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd0/0x2c0 drivers/tty/pty.c:823
1 lock held by syz.4.2001/16131:
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2044 [inline]
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x211/0xcc0 drivers/tty/tty_io.c:2127
1 lock held by syz.6.2022/16431:
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: ptmx_open+0xd0/0x2c0 drivers/tty/pty.c:823
1 lock held by syz.9.2031/16447:
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2044 [inline]
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x211/0xcc0 drivers/tty/tty_io.c:2127
1 lock held by syz.2.2038/16511:
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open_by_driver drivers/tty/tty_io.c:2044 [inline]
 #0: ffffffff8d8b7068 (tty_mutex){+.+.}-{3:3}, at: tty_open+0x211/0xcc0 drivers/tty/tty_io.c:2127
1 lock held by syz-executor/16544:
 #0: ffffffff8e3d6fc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d6fc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
1 lock held by syz-executor/16556:
 #0: ffffffff8e3d6fc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d6fc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
1 lock held by syz-executor/16580:
1 lock held by syz-executor/16633:
 #0: ffffffff8e3d6fc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:78 [inline]
 #0: ffffffff8e3d6fc8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7ed/0xf90 net/core/rtnetlink.c:6481
1 lock held by sed/16645:

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

NMI backtrace for cpu 0
CPU: 0 PID: 29 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a6/0x3e0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xf59/0xfa0 kernel/hung_task.c:379
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>