Kernel panic - not syncing: kernel: panic_on_warn set ...

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.8.175/6963 is trying to acquire lock:
ffffffff8d1260a0 (console_owner){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:339 [inline]
ffffffff8d1260a0 (console_owner){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:232 [inline]
ffffffff8d1260a0 (console_owner){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:292 [inline]
ffffffff8d1260a0 (console_owner){....}-{0:0}, at: console_flush_all+0x10b/0xcf0 kernel/printk/printk.c:2992

but task is already holding lock:
ffff8880263ce418 (&p->pi_lock){-.-.}-{2:2}, at: task_call_func+0x43/0x260 kernel/sched/core.c:4412

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&p->pi_lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xb4/0x100 kernel/locking/spinlock.c:162
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:523 [inline]
       try_to_wake_up+0x5b/0x10e0 kernel/sched/core.c:4233
       kick_pool+0x320/0x420 kernel/workqueue.c:1169
       create_worker+0x61e/0x820 kernel/workqueue.c:2241
       workqueue_init+0x306/0x670 kernel/workqueue.c:6802
       kernel_init_freeable+0x3a7/0x560 init/main.c:1510
       kernel_init+0x1d/0x1c0 init/main.c:1415
       ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
       ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

-> #3 (&pool->lock){-.-.}-{2:2}:
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       __queue_work+0x72f/0xfd0 kernel/workqueue.c:-1
       queue_work_on+0x128/0x1f0 kernel/workqueue.c:1858
       queue_work include/linux/workqueue.h:564 [inline]
       rpm_suspend+0x1133/0x1b60 drivers/base/power/runtime.c:660
       __pm_runtime_idle+0x12f/0x1a0 drivers/base/power/runtime.c:1102
       pm_runtime_put include/linux/pm_runtime.h:454 [inline]
       __device_attach+0x352/0x420 drivers/base/dd.c:1127
       bus_probe_device+0x180/0x260 drivers/base/bus.c:580
       device_add+0x87c/0xc40 drivers/base/core.c:3700
       serial_base_port_add+0x2f6/0x430 drivers/tty/serial/serial_base_bus.c:178
       serial_core_port_device_add drivers/tty/serial/serial_core.c:3377 [inline]
       serial_core_register_port+0x378/0x20b0 drivers/tty/serial/serial_core.c:3418
       serial8250_register_8250_port+0x15fd/0x1f40 drivers/tty/serial/8250/8250_core.c:1142
       serial_pnp_probe+0x577/0x750 drivers/tty/serial/8250/8250_pnp.c:478
       pnp_device_probe+0x305/0x4b0 drivers/pnp/driver.c:111
       call_driver_probe drivers/base/dd.c:-1 [inline]
       really_probe+0x247/0xae0 drivers/base/dd.c:717
       __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:879
       driver_probe_device+0x4f/0x420 drivers/base/dd.c:909
       __driver_attach+0x444/0x6d0 drivers/base/dd.c:1295
       bus_for_each_dev+0x235/0x2b0 drivers/base/bus.c:370
       bus_add_driver+0x340/0x630 drivers/base/bus.c:723
       driver_register+0x23a/0x310 drivers/base/driver.c:246
       serial8250_init+0x9a/0x170 drivers/tty/serial/8250/8250_core.c:1243
       do_one_initcall+0x242/0x790 init/main.c:1210
       do_initcall_level+0x13d/0x1f0 init/main.c:1272
       do_initcalls+0x69/0xd0 init/main.c:1288
       kernel_init_freeable+0x3d9/0x560 init/main.c:1525
       kernel_init+0x1d/0x1c0 init/main.c:1415
       ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
       ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

-> #2 (&dev->power.lock){-...}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xb4/0x100 kernel/locking/spinlock.c:162
       __pm_runtime_resume+0x10f/0x170 drivers/base/power/runtime.c:1169
       pm_runtime_get include/linux/pm_runtime.h:402 [inline]
       __uart_start+0x171/0x3e0 drivers/tty/serial/serial_core.c:148
       uart_write+0x449/0x5d0 drivers/tty/serial/serial_core.c:633
       process_output_block drivers/tty/n_tty.c:580 [inline]
       n_tty_write+0xd3d/0x11e0 drivers/tty/n_tty.c:2395
       iterate_tty_write drivers/tty/tty_io.c:1017 [inline]
       file_tty_write+0x529/0x960 drivers/tty/tty_io.c:1088
       call_write_iter include/linux/fs.h:2018 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x474/0x9a0 fs/read_write.c:584
       ksys_write+0x151/0x260 fs/read_write.c:637
       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

-> #1 (&port_lock_key){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xb4/0x100 kernel/locking/spinlock.c:162
       serial8250_console_write+0x181/0x18b0 drivers/tty/serial/8250/8250_port.c:3439
       console_emit_next_record kernel/printk/printk.c:2944 [inline]
       console_flush_all+0x6ad/0xcf0 kernel/printk/printk.c:3000
       console_unlock+0xad/0x350 kernel/printk/printk.c:3069
       vprintk_emit+0x497/0x610 kernel/printk/printk.c:2341
       _printk+0xde/0x130 kernel/printk/printk.c:2366
       register_console+0xb96/0xf00 kernel/printk/printk.c:3583
       univ8250_console_init+0x45/0x50 drivers/tty/serial/8250/8250_core.c:717
       console_init+0x17b/0x5d0 kernel/printk/printk.c:3726
       start_kernel+0x2c8/0x4e0 init/main.c:982
       x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555
       copy_bootdata+0x0/0xd0 arch/x86/kernel/head64.c:536
       secondary_startup_64_no_verify+0x179/0x17b

-> #0 (console_owner){....}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x37ef/0x7d80 kernel/locking/lockdep.c:5137
       lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
       console_lock_spinning_enable kernel/printk/printk.c:1871 [inline]
       console_emit_next_record kernel/printk/printk.c:2938 [inline]
       console_flush_all+0x676/0xcf0 kernel/printk/printk.c:3000
       console_unlock+0xad/0x350 kernel/printk/printk.c:3069
       vprintk_emit+0x497/0x610 kernel/printk/printk.c:2341
       _printk+0xde/0x130 kernel/printk/printk.c:2366
       panic+0x260/0x720 kernel/panic.c:334
       check_panic_on_warn kernel/panic.c:236 [inline]
       __warn+0x2e0/0x470 kernel/panic.c:681
       __report_bug lib/bug.c:199 [inline]
       report_bug+0x2be/0x4f0 lib/bug.c:219
       handle_bug+0xcf/0x120 arch/x86/kernel/traps.c:310
       exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:345
       asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:606
       __set_task_frozen+0x210/0x2d0 kernel/freezer.c:133
       task_call_func+0x1a2/0x260 kernel/sched/core.c:4427
       __freeze_task kernel/freezer.c:144 [inline]
       freeze_task+0x217/0x3a0 kernel/freezer.c:163
       try_to_freeze_tasks+0x190/0x620 kernel/power/process.c:54
       freeze_processes+0xc9/0x1e0 kernel/power/process.c:137
       suspend_freeze_processes kernel/power/power.h:260 [inline]
       suspend_prepare kernel/power/suspend.c:372 [inline]
       enter_state kernel/power/suspend.c:589 [inline]
       pm_suspend+0x275/0x950 kernel/power/suspend.c:626
       state_store+0x206/0x290 kernel/power/main.c:708
       kernfs_fop_write_iter+0x3a4/0x520 fs/kernfs/file.c:352
       call_write_iter include/linux/fs.h:2018 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x474/0x9a0 fs/read_write.c:584
       ksys_write+0x151/0x260 fs/read_write.c:637
       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

other info that might help us debug this:

Chain exists of:
  console_owner --> &pool->lock --> &p->pi_lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&p->pi_lock);
                               lock(&pool->lock);
                               lock(&p->pi_lock);
  lock(console_owner);

 *** DEADLOCK ***

10 locks held by syz.8.175/6963:
 #0: ffff88805d6620c8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1040
 #1: ffff8880211d2418 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x21e/0x9a0 fs/read_write.c:580
 #2: ffff888023fc7088 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1dc/0x520 fs/kernfs/file.c:343
 #3: ffff88801ce619b8 (kn->active#68){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline]
 #3: ffff88801ce619b8 (kn->active#68){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x236/0x520 fs/kernfs/file.c:344
 #4: ffffffff8cfe58a8 (system_transition_mutex){+.+.}-{3:3}, at: enter_state kernel/power/suspend.c:575 [inline]
 #4: ffffffff8cfe58a8 (system_transition_mutex){+.+.}-{3:3}, at: pm_suspend+0x120/0x950 kernel/power/suspend.c:626
 #5: ffffffff8ce0a058 (tasklist_lock){.+.+}-{2:2}, at: try_to_freeze_tasks+0xe5/0x620 kernel/power/process.c:52
 #6: ffffffff8d144ef8 (freezer_lock){....}-{2:2}, at: freeze_task+0x80/0x3a0 kernel/freezer.c:162
 #7: ffff8880263ce418 (&p->pi_lock){-.-.}-{2:2}, at: task_call_func+0x43/0x260 kernel/sched/core.c:4412
 #8: ffffffff8d126180 (console_lock){+.+.}-{0:0}, at: _printk+0xde/0x130 kernel/printk/printk.c:2366
 #9: ffffffff8d00d990 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:339 [inline]
 #9: ffffffff8d00d990 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:232 [inline]
 #9: ffffffff8d00d990 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:292 [inline]
 #9: ffffffff8d00d990 (console_srcu){....}-{0:0}, at: console_flush_all+0x10b/0xcf0 kernel/printk/printk.c:2992

stack backtrace:
CPU: 1 PID: 6963 Comm: syz.8.175 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
 check_noncircular+0x2fc/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x37ef/0x7d80 kernel/locking/lockdep.c:5137
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 console_lock_spinning_enable kernel/printk/printk.c:1871 [inline]
 console_emit_next_record kernel/printk/printk.c:2938 [inline]
 console_flush_all+0x676/0xcf0 kernel/printk/printk.c:3000
 console_unlock+0xad/0x350 kernel/printk/printk.c:3069
 vprintk_emit+0x497/0x610 kernel/printk/printk.c:2341
 _printk+0xde/0x130 kernel/printk/printk.c:2366
 panic+0x260/0x720 kernel/panic.c:334
 check_panic_on_warn kernel/panic.c:236 [inline]
 __warn+0x2e0/0x470 kernel/panic.c:681
 __report_bug lib/bug.c:199 [inline]
 report_bug+0x2be/0x4f0 lib/bug.c:219
 handle_bug+0xcf/0x120 arch/x86/kernel/traps.c:310
 exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:345
 asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:606
RIP: 0010:__set_task_frozen+0x210/0x2d0 kernel/freezer.c:133
Code: 41 c7 06 00 80 00 00 bd 00 80 00 00 89 e8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 4c 8f 11 00 0f 0b e9 0a ff ff ff e8 40 8f 11 00 <0f> 0b eb 9d 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c 14 fe ff ff 4c
RSP: 0018:ffffc9000383fa50 EFLAGS: 00010083
RAX: ffffffff8175e240 RBX: ffff8880263cda00 RCX: 0000000000080000
RDX: ffffc9001b97d000 RSI: 000000000007cdcd RDI: 000000000007cdce
RBP: 0000000000000003 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000707f2c R12: 0000000000000000
R13: 1ffff11004c79b43 R14: ffff8880263cda18 R15: ffff8880263ce4d8
 task_call_func+0x1a2/0x260 kernel/sched/core.c:4427
 __freeze_task kernel/freezer.c:144 [inline]
 freeze_task+0x217/0x3a0 kernel/freezer.c:163
 try_to_freeze_tasks+0x190/0x620 kernel/power/process.c:54
 freeze_processes+0xc9/0x1e0 kernel/power/process.c:137
 suspend_freeze_processes kernel/power/power.h:260 [inline]
 suspend_prepare kernel/power/suspend.c:372 [inline]
 enter_state kernel/power/suspend.c:589 [inline]
 pm_suspend+0x275/0x950 kernel/power/suspend.c:626
 state_store+0x206/0x290 kernel/power/main.c:708
 kernfs_fop_write_iter+0x3a4/0x520 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x474/0x9a0 fs/read_write.c:584
 ksys_write+0x151/0x260 fs/read_write.c:637
 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: 0033:0x7f2115f9e019
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2116df8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f2116225fa0 RCX: 00007f2115f9e019
RDX: 0000000000000007 RSI: 00002000000001c0 RDI: 0000000000000003
RBP: 00007f211603500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2116226038 R14: 00007f2116225fa0 R15: 00007ffeb7f49d78
 </TASK>
CPU: 1 PID: 6963 Comm: syz.8.175 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
 panic+0x2ca/0x720 kernel/panic.c:340
 check_panic_on_warn kernel/panic.c:236 [inline]
 __warn+0x2e0/0x470 kernel/panic.c:681
 __report_bug lib/bug.c:199 [inline]
 report_bug+0x2be/0x4f0 lib/bug.c:219
 handle_bug+0xcf/0x120 arch/x86/kernel/traps.c:310
 exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:345
 asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:606
RIP: 0010:__set_task_frozen+0x210/0x2d0 kernel/freezer.c:133
Code: 41 c7 06 00 80 00 00 bd 00 80 00 00 89 e8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 4c 8f 11 00 0f 0b e9 0a ff ff ff e8 40 8f 11 00 <0f> 0b eb 9d 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c 14 fe ff ff 4c
RSP: 0018:ffffc9000383fa50 EFLAGS: 00010083
RAX: ffffffff8175e240 RBX: ffff8880263cda00 RCX: 0000000000080000
RDX: ffffc9001b97d000 RSI: 000000000007cdcd RDI: 000000000007cdce
RBP: 0000000000000003 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000707f2c R12: 0000000000000000
R13: 1ffff11004c79b43 R14: ffff8880263cda18 R15: ffff8880263ce4d8
 task_call_func+0x1a2/0x260 kernel/sched/core.c:4427
 __freeze_task kernel/freezer.c:144 [inline]
 freeze_task+0x217/0x3a0 kernel/freezer.c:163
 try_to_freeze_tasks+0x190/0x620 kernel/power/process.c:54
 freeze_processes+0xc9/0x1e0 kernel/power/process.c:137
 suspend_freeze_processes kernel/power/power.h:260 [inline]
 suspend_prepare kernel/power/suspend.c:372 [inline]
 enter_state kernel/power/suspend.c:589 [inline]
 pm_suspend+0x275/0x950 kernel/power/suspend.c:626
 state_store+0x206/0x290 kernel/power/main.c:708
 kernfs_fop_write_iter+0x3a4/0x520 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x474/0x9a0 fs/read_write.c:584
 ksys_write+0x151/0x260 fs/read_write.c:637
 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: 0033:0x7f2115f9e019
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2116df8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f2116225fa0 RCX: 00007f2115f9e019
RDX: 0000000000000007 RSI: 00002000000001c0 RDI: 0000000000000003
RBP: 00007f211603500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2116226038 R14: 00007f2116225fa0 R15: 00007ffeb7f49d78
 </TASK>
Shutting down cpus with NMI
Kernel Offset: disabled
Rebooting in 86400 seconds..