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

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.58/6258 is trying to acquire lock:
ffffffff8eb4bf40 (console_owner){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:305 [inline]
ffffffff8eb4bf40 (console_owner){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline]
ffffffff8eb4bf40 (console_owner){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline]
ffffffff8eb4bf40 (console_owner){....}-{0:0}, at: console_flush_one_record kernel/printk/printk.c:3246 [inline]
ffffffff8eb4bf40 (console_owner){....}-{0:0}, at: console_flush_all+0x123/0xaf0 kernel/printk/printk.c:3343

but task is already holding lock:
ffff8880523ba990 (&p->pi_lock){-.-.}-{2:2}, at: task_call_func+0x42/0x260 kernel/sched/core.c:4476

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&p->pi_lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
       _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:572 [inline]
       try_to_wake_up+0x67/0x14d0 kernel/sched/core.c:4292
       __wake_up_common kernel/sched/wait.c:108 [inline]
       __wake_up_common_lock+0x13a/0x1f0 kernel/sched/wait.c:125
       tty_port_default_wakeup+0xc8/0x100 drivers/tty/tty_port.c:67
       serial8250_tx_chars+0x70e/0x950 drivers/tty/serial/8250/8250_port.c:1723
       serial8250_handle_irq+0x166/0x550 drivers/tty/serial/8250/8250_port.c:1853
       serial8250_default_handle_irq+0xbf/0x1e0 drivers/tty/serial/8250/8250_port.c:1867
       serial8250_interrupt+0x8d/0x160 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x216/0x9a0 kernel/irq/handle.c:209
       handle_irq_event_percpu kernel/irq/handle.c:246 [inline]
       handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:263
       handle_edge_irq+0x1f4/0x8a0 kernel/irq/chip.c:859
       generic_handle_irq_desc include/linux/irqdesc.h:188 [inline]
       handle_irq arch/x86/kernel/irq.c:209 [inline]
       call_irq_handler arch/x86/kernel/irq.c:-1 [inline]
       __common_interrupt+0x141/0x1f0 arch/x86/kernel/irq.c:280
       common_interrupt+0xb6/0xe0 arch/x86/kernel/irq.c:273
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:665
       __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:188 [inline]
       _raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:206
       spin_unlock_irq include/linux/spinlock.h:402 [inline]
       __rpm_callback+0xa7/0x950 drivers/base/power/runtime.c:383
       rpm_callback drivers/base/power/runtime.c:460 [inline]
       rpm_resume+0x104d/0x16d0 drivers/base/power/runtime.c:939
       rpm_resume+0x8b0/0x16d0 drivers/base/power/runtime.c:917
       pm_runtime_work+0x103/0x1b0 drivers/base/power/runtime.c:1004
       process_one_work kernel/workqueue.c:3322 [inline]
       process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
       worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
       kthread+0x388/0x470 kernel/kthread.c:436
       ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #2 (&tty->write_wait){-.-.}-{3:3}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
       _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
       __wake_up_common_lock+0x30/0x1f0 kernel/sched/wait.c:124
       tty_port_default_wakeup+0xc8/0x100 drivers/tty/tty_port.c:67
       serial8250_tx_chars+0x70e/0x950 drivers/tty/serial/8250/8250_port.c:1723
       serial8250_handle_irq+0x166/0x550 drivers/tty/serial/8250/8250_port.c:1853
       serial8250_default_handle_irq+0xbf/0x1e0 drivers/tty/serial/8250/8250_port.c:1867
       serial8250_interrupt+0x8d/0x160 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x216/0x9a0 kernel/irq/handle.c:209
       handle_irq_event_percpu kernel/irq/handle.c:246 [inline]
       handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:263
       handle_edge_irq+0x1f4/0x8a0 kernel/irq/chip.c:859
       generic_handle_irq_desc include/linux/irqdesc.h:188 [inline]
       handle_irq arch/x86/kernel/irq.c:209 [inline]
       call_irq_handler arch/x86/kernel/irq.c:-1 [inline]
       __common_interrupt+0x141/0x1f0 arch/x86/kernel/irq.c:280
       common_interrupt+0xb6/0xe0 arch/x86/kernel/irq.c:273
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:665
       __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:188 [inline]
       _raw_spin_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:206
       spin_unlock_irq include/linux/spinlock.h:402 [inline]
       __rpm_callback+0xa7/0x950 drivers/base/power/runtime.c:383
       rpm_callback drivers/base/power/runtime.c:460 [inline]
       rpm_resume+0x104d/0x16d0 drivers/base/power/runtime.c:939
       rpm_resume+0x8b0/0x16d0 drivers/base/power/runtime.c:917
       pm_runtime_work+0x103/0x1b0 drivers/base/power/runtime.c:1004
       process_one_work kernel/workqueue.c:3322 [inline]
       process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
       worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
       kthread+0x388/0x470 kernel/kthread.c:436
       ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #1 (&port_lock_key){-.-.}-{3:3}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
       _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
       uart_port_lock_irqsave include/linux/serial_core.h:719 [inline]
       serial8250_console_write+0x153/0x1ba0 drivers/tty/serial/8250/8250_port.c:3344
       console_emit_next_record kernel/printk/printk.c:3183 [inline]
       console_flush_one_record kernel/printk/printk.c:3269 [inline]
       console_flush_all+0x6ea/0xaf0 kernel/printk/printk.c:3343
       __console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
       console_unlock+0xd1/0x1c0 kernel/printk/printk.c:3413
       vprintk_emit+0x485/0x560 kernel/printk/printk.c:2479
       _printk+0xdd/0x130 kernel/printk/printk.c:2504
       register_console+0xbc3/0xfc0 kernel/printk/printk.c:4208
       univ8250_console_init+0x3a/0x70 drivers/tty/serial/8250/8250_core.c:515
       console_init+0x10b/0x4a0 kernel/printk/printk.c:4407
       start_kernel+0x238/0x3e0 init/main.c:1112
       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x137/0x1b0 arch/x86/kernel/head64.c:291
       common_startup_64+0x13e/0x157

-> #0 (console_owner){....}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain kernel/locking/lockdep.c:3908 [inline]
       __lock_acquire+0x1520/0x2cf0 kernel/locking/lockdep.c:5237
       lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
       console_lock_spinning_enable kernel/printk/printk.c:1902 [inline]
       console_emit_next_record kernel/printk/printk.c:3177 [inline]
       console_flush_one_record kernel/printk/printk.c:3269 [inline]
       console_flush_all+0x693/0xaf0 kernel/printk/printk.c:3343
       __console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
       console_unlock+0xd1/0x1c0 kernel/printk/printk.c:3413
       vprintk_emit+0x485/0x560 kernel/printk/printk.c:2479
       _printk+0xdd/0x130 kernel/printk/printk.c:2504
       vpanic+0x476/0xa60 kernel/panic.c:640
       panic+0xc5/0xd0 kernel/panic.c:788
       check_panic_on_warn kernel/panic.c:525 [inline]
       __warn+0x315/0x4c0 kernel/panic.c:1104
       __report_bug+0x276/0x570 lib/bug.c:254
       report_bug+0x16a/0x220 lib/bug.c:286
       handle_bug+0x9c/0x200 arch/x86/kernel/traps.c:436
       exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:490
       asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:593
       __set_task_frozen+0x260/0x340 kernel/freezer.c:139
       task_call_func+0x1aa/0x260 kernel/sched/core.c:4495
       __freeze_task kernel/freezer.c:150 [inline]
       freeze_task+0x229/0x3b0 kernel/freezer.c:169
       try_to_freeze_tasks+0x190/0x620 kernel/power/process.c:54
       freeze_processes+0xce/0x1e0 kernel/power/process.c:137
       hibernate+0x247/0x680 kernel/power/hibernate.c:801
       state_store+0x234/0x290 kernel/power/main.c:821
       kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
       new_sync_write fs/read_write.c:595 [inline]
       vfs_write+0x612/0xba0 fs/read_write.c:687
       ksys_write+0x150/0x270 fs/read_write.c:739
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  console_owner --> &tty->write_wait --> &p->pi_lock

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

10 locks held by syz.2.58/6258:
 #0: ffff88807a374d30 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1259
 #1: ffff88805014c450 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
 #1: ffff88805014c450 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
 #2: ffff88807f4c7c80 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540 fs/kernfs/file.c:336
 #3: ffff88801e2a11e8 (kn->active#59){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
 #3: ffff88801e2a11e8 (kn->active#59){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22b/0x540 fs/kernfs/file.c:337
 #4: ffffffff8ea02160 (system_transition_mutex){+.+.}-{4:4}, at: lock_system_sleep+0x49/0x70 kernel/power/main.c:71
 #5: ffffffff8e80a058 (tasklist_lock){.+.+}-{3:3}, at: try_to_freeze_tasks+0xe5/0x620 kernel/power/process.c:52
 #6: ffffffff8eb7b7b8 (freezer_lock){....}-{3:3}, at: freeze_task+0x7e/0x3b0 kernel/freezer.c:168
 #7: ffff8880523ba990 (&p->pi_lock){-.-.}-{2:2}, at: task_call_func+0x42/0x260 kernel/sched/core.c:4476
 #8: ffffffff8eb4bfa0 (console_lock){+.+.}-{0:0}, at: _printk+0xdd/0x130 kernel/printk/printk.c:2504
 #9: ffffffff8ea33838 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:305 [inline]
 #9: ffffffff8ea33838 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline]
 #9: ffffffff8ea33838 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline]
 #9: ffffffff8ea33838 (console_srcu){....}-{0:0}, at: console_flush_one_record kernel/printk/printk.c:3246 [inline]
 #9: ffffffff8ea33838 (console_srcu){....}-{0:0}, at: console_flush_all+0x123/0xaf0 kernel/printk/printk.c:3343

stack backtrace:
CPU: 1 UID: 0 PID: 6258 Comm: syz.2.58 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
 <TASK>
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043
 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain kernel/locking/lockdep.c:3908 [inline]
 __lock_acquire+0x1520/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
 console_lock_spinning_enable kernel/printk/printk.c:1902 [inline]
 console_emit_next_record kernel/printk/printk.c:3177 [inline]
 console_flush_one_record kernel/printk/printk.c:3269 [inline]
 console_flush_all+0x693/0xaf0 kernel/printk/printk.c:3343
 __console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
 console_unlock+0xd1/0x1c0 kernel/printk/printk.c:3413
 vprintk_emit+0x485/0x560 kernel/printk/printk.c:2479
 _printk+0xdd/0x130 kernel/printk/printk.c:2504
 vpanic+0x476/0xa60 kernel/panic.c:640
 panic+0xc5/0xd0 kernel/panic.c:788
 check_panic_on_warn kernel/panic.c:525 [inline]
 __warn+0x315/0x4c0 kernel/panic.c:1104
 __report_bug+0x276/0x570 lib/bug.c:254
 report_bug+0x16a/0x220 lib/bug.c:286
 handle_bug+0x9c/0x200 arch/x86/kernel/traps.c:436
 exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:490
 asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:593
RIP: 0010:__set_task_frozen+0x260/0x340 kernel/freezer.c:139
Code: 00 80 00 00 89 e8 5b 41 5c 41 5d 41 5e 41 5f 5d e9 20 43 5e ff cc e8 7f 14 15 00 90 0f 0b 90 e9 f7 fe ff ff e8 71 14 15 00 90 <0f> 0b 90 eb 93 44 89 e1 80 e1 07 80 c1 03 38 c1 0f 8c c3 fd ff ff
RSP: 0018:ffffc9000575fa10 EFLAGS: 00010083
RAX: ffffffff81b1fdff RBX: ffff8880523b9f00 RCX: 0000000000080000
RDX: ffffc90005c01000 RSI: 000000000000c582 RDI: 000000000000c583
RBP: 0000000000000003 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff81b1fba0 R12: ffff8880523b9f18
R13: 1ffff1100a4773e3 R14: 0000000000000000 R15: ffff8880523baa98
 task_call_func+0x1aa/0x260 kernel/sched/core.c:4495
 __freeze_task kernel/freezer.c:150 [inline]
 freeze_task+0x229/0x3b0 kernel/freezer.c:169
 try_to_freeze_tasks+0x190/0x620 kernel/power/process.c:54
 freeze_processes+0xce/0x1e0 kernel/power/process.c:137
 hibernate+0x247/0x680 kernel/power/hibernate.c:801
 state_store+0x234/0x290 kernel/power/main.c:821
 kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f190579e019
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:00007f1906753028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1905a25fa0 RCX: 00007f190579e019
RDX: 0000000000000004 RSI: 0000200000000200 RDI: 0000000000000003
RBP: 00007f190583500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1905a26038 R14: 00007f1905a25fa0 R15: 00007ffcbc16cc08
 </TASK>
CPU: 1 UID: 0 PID: 6258 Comm: syz.2.58 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
 <TASK>
 vpanic+0x56c/0xa60 kernel/panic.c:651
 panic+0xc5/0xd0 kernel/panic.c:788
 check_panic_on_warn kernel/panic.c:525 [inline]
 __warn+0x315/0x4c0 kernel/panic.c:1104
 __report_bug+0x276/0x570 lib/bug.c:254
 report_bug+0x16a/0x220 lib/bug.c:286
 handle_bug+0x9c/0x200 arch/x86/kernel/traps.c:436
 exc_invalid_op+0x1a/0x50 arch/x86/kernel/traps.c:490
 asm_exc_invalid_op+0x1a/0x20 arch/x86/include/asm/idtentry.h:593
RIP: 0010:__set_task_frozen+0x260/0x340 kernel/freezer.c:139
Code: 00 80 00 00 89 e8 5b 41 5c 41 5d 41 5e 41 5f 5d e9 20 43 5e ff cc e8 7f 14 15 00 90 0f 0b 90 e9 f7 fe ff ff e8 71 14 15 00 90 <0f> 0b 90 eb 93 44 89 e1 80 e1 07 80 c1 03 38 c1 0f 8c c3 fd ff ff
RSP: 0018:ffffc9000575fa10 EFLAGS: 00010083
RAX: ffffffff81b1fdff RBX: ffff8880523b9f00 RCX: 0000000000080000
RDX: ffffc90005c01000 RSI: 000000000000c582 RDI: 000000000000c583
RBP: 0000000000000003 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff81b1fba0 R12: ffff8880523b9f18
R13: 1ffff1100a4773e3 R14: 0000000000000000 R15: ffff8880523baa98
 task_call_func+0x1aa/0x260 kernel/sched/core.c:4495
 __freeze_task kernel/freezer.c:150 [inline]
 freeze_task+0x229/0x3b0 kernel/freezer.c:169
 try_to_freeze_tasks+0x190/0x620 kernel/power/process.c:54
 freeze_processes+0xce/0x1e0 kernel/power/process.c:137
 hibernate+0x247/0x680 kernel/power/hibernate.c:801
 state_store+0x234/0x290 kernel/power/main.c:821
 kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f190579e019
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:00007f1906753028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f1905a25fa0 RCX: 00007f190579e019
RDX: 0000000000000004 RSI: 0000200000000200 RDI: 0000000000000003
RBP: 00007f190583500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1905a26038 R14: 00007f1905a25fa0 R15: 00007ffcbc16cc08
 </TASK>
Shutting down cpus with NMI
Kernel Offset: disabled
Rebooting in 86400 seconds..