syzbot

INFO: task syz.5.1696:14233 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.5.1696      state:D stack:27256 pid:14233 tgid:14232 ppid:13974  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7005
 schedule_timeout+0x1b2/0x280 kernel/time/sleep_timeout.c:75
 ___down_common kernel/locking/semaphore.c:268 [inline]
 __down_common+0x396/0x790 kernel/locking/semaphore.c:293
 down+0x74/0xa0 kernel/locking/semaphore.c:100
 console_lock+0x5b/0xa0 kernel/printk/printk.c:2896
 class_console_lock_constructor include/linux/console.h:736 [inline]
 con_install+0x99/0x620 drivers/tty/vt/vt.c:3640
 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:411
 do_dentry_open+0x6d8/0x1660 fs/open.c:949
 vfs_open+0x82/0x3f0 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x208c/0x31a0 fs/namei.c:4830
 do_file_open+0x20e/0x430 fs/namei.c:4859
 do_sys_openat2+0x10d/0x1e0 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0d9779c799
RSP: 002b:00007f0d98694028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f0d97a15fa0 RCX: 00007f0d9779c799
RDX: 0000000000040001 RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007f0d97832bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0d97a16038 R14: 00007f0d97a15fa0 R15: 00007fffed6c7e08
 </TASK>
INFO: task syz.6.1697:14237 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.6.1697      state:D stack:26792 pid:14237 tgid:14235 ppid:14122  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5295 [inline]
 __schedule+0xfee/0x6120 kernel/sched/core.c:6908
 __schedule_loop kernel/sched/core.c:6990 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:7005
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7062
 __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:411
 do_dentry_open+0x6d8/0x1660 fs/open.c:949
 vfs_open+0x82/0x3f0 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x208c/0x31a0 fs/namei.c:4830
 do_file_open+0x20e/0x430 fs/namei.c:4859
 do_sys_openat2+0x10d/0x1e0 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x12d/0x210 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f05c6f9c799
RSP: 002b:00007f05c7f0d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f05c7215fa0 RCX: 00007f05c6f9c799
RDX: 0000000000109401 RSI: 0000200000000040 RDI: ffffffffffffff9c
RBP: 00007f05c7032bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f05c7216038 R14: 00007f05c7215fa0 R15: 00007ffdde236688
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/31:
 #0: ffffffff8e7e9220 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8e7e9220 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8e7e9220 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
2 locks held by kworker/u10:24/11560:
 #0: ffff88801ebc0148 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x1287/0x1920 kernel/workqueue.c:3250
 #1: ffffc9000e5efd08 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x93c/0x1920 kernel/workqueue.c:3251
7 locks held by kworker/u10:30/11887:
2 locks held by getty/12607:
 #0: ffff8880379ba0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc900037352f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x1500 drivers/tty/n_tty.c:2211
2 locks held by syz.0.1613/13765:
 #0: ffffffff906bfd30 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec59468 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_threads_set_doit+0x6c1/0xc00 fs/nfsd/nfsctl.c:1597
4 locks held by syz.4.1657/13997:
2 locks held by syz.2.1675/14114:
2 locks held by syz.5.1696/14233:
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
 #1: ffff88805dfba1c0 (&tty->legacy_mutex){+.+.}-{4:4}, at: tty_init_dev.part.0+0x39/0x470 drivers/tty/tty_io.c:1406
1 lock held by syz.6.1697/14237:
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.3.1716/14371:
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
2 locks held by syz.7.1721/14427:
 #0: ffffffff906bfd30 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
 #1: ffffffff8ec59468 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_nl_listener_set_doit+0xd5/0x1a80 fs/nfsd/nfsctl.c:1893
1 lock held by syz.9.1727/14452:
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
4 locks held by syz.8.1731/14472:
 #0: ffff88805bc05cf8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1261
 #1: ffff888036008420 (sb_writers#7){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:740
 #2: ffff888026ba5c88 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:343
 #3: ffff88801eab8698 (kn->active#240){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #3: ffff88801eab8698 (kn->active#240){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x332/0x5f0 fs/kernfs/file.c:344
1 lock held by syz.1.1736/14617:
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.0.1737/14711:
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.4.1733/14746:
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.2.1742/14804:
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.2.1742/14806:
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
2 locks held by syz-executor/14818:
 #0: ffff88806b5ac0e0 (&type->s_umount_key#52){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88806b5ac0e0 (&type->s_umount_key#52){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
 #0: ffff88806b5ac0e0 (&type->s_umount_key#52){+.+.}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
 #0: ffff88806b5ac0e0 (&type->s_umount_key#52){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
 #1: ffffffff8ec59468 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
1 lock held by syz.5.1738/14826:
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.3.1747/14897:
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
2 locks held by syz-executor/14902:
 #0: ffff88806740e0e0 (&type->s_umount_key#52){+.+.}-{4:4}, at: __super_lock fs/super.c:58 [inline]
 #0: ffff88806740e0e0 (&type->s_umount_key#52){+.+.}-{4:4}, at: __super_lock_excl fs/super.c:73 [inline]
 #0: ffff88806740e0e0 (&type->s_umount_key#52){+.+.}-{4:4}, at: deactivate_super fs/super.c:508 [inline]
 #0: ffff88806740e0e0 (&type->s_umount_key#52){+.+.}-{4:4}, at: deactivate_super+0xdf/0x110 fs/super.c:505
 #1: ffffffff8ec59468 (nfsd_mutex){+.+.}-{4:4}, at: nfsd_shutdown_threads+0x5b/0xf0 fs/nfsd/nfssvc.c:576
1 lock held by syz.6.1756/15001:
1 lock held by syz.7.1760/15014:
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.7.1760/15015:
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x539/0xfa0 drivers/tty/tty_io.c:2120
1 lock held by syz.8.1782/15154:
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: ptmx_open drivers/tty/pty.c:798 [inline]
 #0: ffffffff8f4f04c8 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x150/0x3c0 drivers/tty/pty.c:765
2 locks held by syz.6.1783/15166:
3 locks held by syz-executor/15196:
2 locks held by syz-executor/15212:

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

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 02/12/2026
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+0xd25/0x1050 kernel/hung_task.c:515
 kthread+0x370/0x450 kernel/kthread.c:467
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>