syzbot

INFO: task syz.6.4051:24296 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.4051      state:D stack:26872 pid:24296 tgid:24295 ppid:24151  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0xfe4/0x5e10 kernel/sched/core.c:6867
 __schedule_loop kernel/sched/core.c:6949 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:6964
 schedule_timeout+0x1b2/0x280 kernel/time/sleep_timeout.c:75
 ___down_common kernel/locking/semaphore.c:268 [inline]
 __down_common+0x396/0x6c0 kernel/locking/semaphore.c:293
 down+0x74/0xa0 kernel/locking/semaphore.c:100
 console_lock+0x5b/0xa0 kernel/printk/printk.c:2843
 class_console_lock_constructor include/linux/console.h:737 [inline]
 con_install+0x99/0x620 drivers/tty/vt/vt.c:3647
 tty_driver_install_tty drivers/tty/tty_io.c:1295 [inline]
 tty_init_dev.part.0+0x9e/0x470 drivers/tty/tty_io.c:1407
 tty_init_dev include/linux/err.h:78 [inline]
 tty_open_by_driver drivers/tty/tty_io.c:2073 [inline]
 tty_open+0xa63/0xfa0 drivers/tty/tty_io.c:2120
 chrdev_open+0x234/0x6a0 fs/char_dev.c:414
 do_dentry_open+0x73e/0x1570 fs/open.c:962
 vfs_open+0x82/0x3f0 fs/open.c:1094
 do_open fs/namei.c:4637 [inline]
 path_openat+0x21dc/0x3120 fs/namei.c:4796
 do_filp_open+0x1f7/0x420 fs/namei.c:4823
 do_sys_openat2+0x12e/0x220 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1447
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f837ad9acb9
RSP: 002b:00007f837bbbd028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f837b015fa0 RCX: 00007f837ad9acb9
RDX: 0000000000040741 RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007f837ae08bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f837b016038 R14: 00007f837b015fa0 R15: 00007fff1cff9668
 </TASK>
INFO: task syz.6.4051:24299 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.4051      state:D stack:27928 pid:24299 tgid:24295 ppid:24151  task_flags:0x400140 flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0xfe4/0x5e10 kernel/sched/core.c:6867
 __schedule_loop kernel/sched/core.c:6949 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:6964
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7021
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0xc9a/0x1b90 kernel/locking/mutex.c:776
 tty_release_struct+0xad/0xe0 drivers/tty/tty_io.c:1691
 tty_release+0xd7a/0x1300 drivers/tty/tty_io.c:1852
 __fput+0x3ff/0xb40 fs/file_table.c:468
 task_work_run+0x150/0x240 kernel/task_work.c:233
 get_signal+0x1bd/0x21e0 kernel/signal.c:2807
 arch_do_signal_or_restart+0x91/0x770 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:41 [inline]
 exit_to_user_mode_loop+0x86/0x4b0 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x4ea/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f837ad9acb9
RSP: 002b:00007f837bb9c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: 00000000000e9800 RBX: 00007f837b016090 RCX: 00007f837ad9acb9
RDX: 00000000fffffdef RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f837ae08bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f837b016128 R14: 00007f837b016090 R15: 00007fff1cff9668
 </TASK>
INFO: task syz.5.4065:24343 blocked for more than 143 seconds.
      Tainted: G             L      syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.5.4065      state:D stack:25880 pid:24343 tgid:24342 ppid:24149  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0xfe4/0x5e10 kernel/sched/core.c:6867
 __schedule_loop kernel/sched/core.c:6949 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:6964
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7021
 __mutex_lock_common kernel/locking/mutex.c:692 [inline]
 __mutex_lock+0xc9a/0x1b90 kernel/locking/mutex.c:776
 tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
 chrdev_open+0x234/0x6a0 fs/char_dev.c:414
 do_dentry_open+0x73e/0x1570 fs/open.c:962
 vfs_open+0x82/0x3f0 fs/open.c:1094
 do_open fs/namei.c:4637 [inline]
 path_openat+0x21dc/0x3120 fs/namei.c:4796
 do_filp_open+0x1f7/0x420 fs/namei.c:4823
 do_sys_openat2+0x12e/0x220 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1447
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fefd719acb9
RSP: 002b:00007fefd80c5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fefd7415fa0 RCX: 00007fefd719acb9
RDX: 0000000000000800 RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007fefd7208bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fefd7416038 R14: 00007fefd7415fa0 R15: 00007ffef1a85ca8
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e5e31a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff8e5e31a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff8e5e31a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
3 locks held by kworker/u9:4/5840:
 #0: ffff888050b17148 ((wq_completion)hci15){+.+.}-{0:0}, at: process_one_work+0x11ae/0x1840 kernel/workqueue.c:3232
 #1: ffffc9000419fc98 ((work_completion)(&hdev->power_on)){+.+.}-{0:0}, at: process_one_work+0x927/0x1840 kernel/workqueue.c:3233
 #2: ffff88802ba30ec0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_dev_do_open+0x22/0xb0 net/bluetooth/hci_core.c:428
2 locks held by syz.4.2682/18049:
 #0: ffff8880542120e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff8880542120e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff8880542120e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: deactivate_super fs/super.c:506 [inline]
 #0: ffff8880542120e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:503
 #1: ffffffff8ea47168 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:575
2 locks held by getty/20746:
 #0: ffff88803607d0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000b6d32f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x1500 drivers/tty/n_tty.c:2211
2 locks held by kworker/u8:47/24102:
2 locks held by syz.2.4027/24133:
6 locks held by syz.3.4028/24136:
2 locks held by syz.6.4051/24296:
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
 #1: ffff8880355531c0 (&tty->legacy_mutex){+.+.}-{4:4}, at: tty_init_dev.part.0+0x39/0x470 drivers/tty/tty_io.c:1406
1 lock held by syz.6.4051/24299:
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_release_struct+0xad/0xe0 drivers/tty/tty_io.c:1691
1 lock held by syz.5.4065/24343:
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
2 locks held by syz-executor/24564:
 #0: ffff888035bb60e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff888035bb60e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff888035bb60e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: deactivate_super fs/super.c:506 [inline]
 #0: ffff888035bb60e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:503
 #1: ffffffff8ea47168 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:575
2 locks held by syz-executor/24892:
 #0: ffff8880592ec0e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: __super_lock fs/super.c:57 [inline]
 #0: ffff8880592ec0e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:72 [inline]
 #0: ffff8880592ec0e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: deactivate_super fs/super.c:506 [inline]
 #0: ffff8880592ec0e0 (&type->s_umount_key#51){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:503
 #1: ffffffff8ea47168 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:575
1 lock held by syz.7.4218/25071:
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.7.4218/25072:
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.2.4345/25671:
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.3.4358/25729:
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.6.4372/25801:
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f2d6808 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz-executor/25838:
 #0: ffffffff903f44a8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #0: ffffffff903f44a8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #0: ffffffff903f44a8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x8bb/0x2380 net/core/rtnetlink.c:4071
9 locks held by syz-executor/25892:
2 locks held by syz.5.4392/25931:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x1d7/0x230 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x141/0x190 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xcc3/0xfe0 kernel/hung_task.c:515
 kthread+0x3b3/0x730 kernel/kthread.c:463
 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>