syzbot

INFO: task syz.9.3227:16766 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.9.3227      state:D stack:27016 pid:16766 tgid:16763 ppid:14047  task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0x15dd/0x52d0 kernel/sched/core.c:6911
 __schedule_loop kernel/sched/core.c:6993 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7008
 schedule_timeout+0xc3/0x2c0 kernel/time/sleep_timeout.c:75
 ___down_common kernel/locking/semaphore.c:268 [inline]
 __down_common+0x321/0x730 kernel/locking/semaphore.c:293
 down+0x80/0xd0 kernel/locking/semaphore.c:100
 console_lock+0x58/0x90 kernel/printk/printk.c:2896
 class_console_lock_constructor include/linux/console.h:736 [inline]
 con_install+0x97/0x770 drivers/tty/vt/vt.c:3648
 tty_driver_install_tty drivers/tty/tty_io.c:1295 [inline]
 tty_init_dev+0xd7/0x4d0 drivers/tty/tty_io.c:1407
 tty_open_by_driver drivers/tty/tty_io.c:2073 [inline]
 tty_open+0x862/0xd70 drivers/tty/tty_io.c:2120
 chrdev_open+0x4cd/0x5e0 fs/char_dev.c:411
 do_dentry_open+0x785/0x14e0 fs/open.c:949
 vfs_open+0x3b/0x340 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4830
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 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+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff9d455cfce
RSP: 002b:00007ff9d5391b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007ff9d53926c0 RCX: 00007ff9d455cfce
RDX: 0000000000000002 RSI: 00007ff9d5391c00 RDI: ffffffffffffff9c
RBP: 00007ff9d4632c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff9d4816218 R14: 00007ff9d4816180 R15: 00007fffb53a6938
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/32:
 #0: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #0: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #0: ffffffff8e75e5e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
3 locks held by kworker/u8:5/87:
2 locks held by getty/5581:
 #0: ffff8880367b20a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc9000331e2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13c0 drivers/tty/n_tty.c:2211
3 locks held by kworker/u9:1/15142:
 #0: ffff888027011148 ((wq_completion)hci8){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #0: ffff888027011148 ((wq_completion)hci8){+.+.}-{0:0}, at: process_scheduled_works+0xa52/0x18c0 kernel/workqueue.c:3359
 #1: ffffc9000f2b7c40 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3252 [inline]
 #1: ffffc9000f2b7c40 ((work_completion)(&hdev->cmd_sync_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa8d/0x18c0 kernel/workqueue.c:3359
 #2: ffff88803f6d4ec0 (&hdev->req_lock){+.+.}-{4:4}, at: hci_cmd_sync_work+0x1d3/0x400 net/bluetooth/hci_sync.c:331
6 locks held by syz.8.3008/15802:
2 locks held by syz.9.3227/16766:
 #0: ffffffff8eff4508 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8eff4508 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x22d/0xd70 drivers/tty/tty_io.c:2120
 #1: ffff8880348b81c0 (&tty->legacy_mutex){+.+.}-{4:4}, at: tty_init_dev+0x74/0x4d0 drivers/tty/tty_io.c:1406
1 lock held by syz.3.3245/16867:
 #0: ffffffff8eff4508 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8eff4508 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x22d/0xd70 drivers/tty/tty_io.c:2120
1 lock held by syz.7.3252/16904:
 #0: ffffffff8eff4508 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8eff4508 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x22d/0xd70 drivers/tty/tty_io.c:2120
4 locks held by syz-executor/17755:
1 lock held by syz.0.3404/17823:
 #0: ffffffff8eff4508 (tty_mutex){+.+.}-{4:4}, at: tty_open_by_driver drivers/tty/tty_io.c:2037 [inline]
 #0: ffffffff8eff4508 (tty_mutex){+.+.}-{4:4}, at: tty_open+0x22d/0xd70 drivers/tty/tty_io.c:2120
2 locks held by syz.4.3428/17931:
1 lock held by syz.9.3471/18214:
 #0: ffffffff8eff4508 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
 #0: ffffffff8eff4508 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x108/0x340 drivers/tty/pty.c:798
1 lock held by syz.3.3492/18344:
 #0: ffffffff8eff4508 (tty_mutex){+.+.}-{4:4}, at: class_mutex_constructor include/linux/mutex.h:253 [inline]
 #0: ffffffff8eff4508 (tty_mutex){+.+.}-{4:4}, at: ptmx_open+0x108/0x340 drivers/tty/pty.c:798
1 lock held by syz.8.3496/18365:
2 locks held by syz.8.3496/18368:
1 lock held by syz.1.3501/18392:
1 lock held by cmp/18391:

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

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 32 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_lvl+0xe8/0x150 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 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+0x135/0x170 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xfd9/0x1030 kernel/hung_task.c:515
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63
Code: 5e 6c 02 e9 8e 82 61 f5 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d e3 a2 1a 00 fb f4 <e9> 67 82 61 f5 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffc90000197e20 EFLAGS: 00000246
RAX: 000000000280b935 RBX: ffffffff819a913a RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8def8bf9 RDI: ffffffff8c27c900
RBP: ffffc90000197f10 R08: ffff8880b873399b R09: 1ffff110170e6733
R10: dffffc0000000000 R11: ffffed10170e6734 R12: 0000000000000001
R13: 1ffff11003ad0000 R14: 0000000000000001 R15: 1ffff11003ad0000
FS:  0000000000000000(0000) GS:ffff88812555d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcbc71456b8 CR3: 00000000a1bd7000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/kernel/process.c:766 [inline]
 default_idle+0x9/0x20 arch/x86/kernel/process.c:767
 default_idle_call+0x72/0xb0 kernel/sched/idle.c:122
 cpuidle_idle_call kernel/sched/idle.c:199 [inline]
 do_idle+0x36a/0x5f0 kernel/sched/idle.c:352
 cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:451
 start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312
 common_startup_64+0x13e/0x147
 </TASK>