------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.5.1376/10600 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:
ffff8880b863b160 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xb2/0x160 kernel/sched/core.c:675

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&rq->__lock){-.-.}-{2:2}:
       _raw_spin_lock_nested+0x32/0x50 kernel/locking/spinlock.c:382
       raw_spin_rq_lock_nested+0x2d/0x160 kernel/sched/core.c:667
       raw_spin_rq_lock kernel/sched/sched.h:1653 [inline]
       _task_rq_lock+0xc0/0x440 kernel/sched/core.c:762
       cgroup_move_task+0x9a/0x350 kernel/sched/psi.c:1176
       css_set_move_task+0x62d/0x820 kernel/cgroup/cgroup.c:925
       cgroup_post_fork+0x209/0x9b0 kernel/cgroup/cgroup.c:7009
       copy_process+0x402b/0x4390 kernel/fork.c:2550
       kernel_clone+0x2d7/0x940 kernel/fork.c:2748
       user_mode_thread+0x110/0x180 kernel/fork.c:2824
       rest_init+0x23/0x300 init/main.c:682
       start_kernel+0x392/0x3e0 init/main.c:1175
       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

-> #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
       folio_put include/linux/mm.h:2123 [inline]
       filemap_read+0xdcb/0x11e0 mm/filemap.c:2887
       new_sync_read fs/read_write.c:493 [inline]
       vfs_read+0x595/0xa80 fs/read_write.c:574
       ksys_read+0x150/0x270 fs/read_write.c:716
       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

-> #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
       native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
       pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63
       arch_safe_halt arch/x86/kernel/process.c:767 [inline]
       default_idle+0x9/0x20 arch/x86/kernel/process.c:768
       default_idle_call+0x72/0xb0 kernel/sched/idle.c:122
       cpuidle_idle_call kernel/sched/idle.c:199 [inline]
       do_idle+0x2e0/0x540 kernel/sched/idle.c:355
       cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:454
       start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:312
       common_startup_64+0x13e/0x157

-> #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
       __report_bug+0x349/0x570 lib/bug.c:248
       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
       lockdep_assert_rq_held kernel/sched/sched.h:1641 [inline]
       update_rq_clock+0x34d/0x560 kernel/sched/core.c:865
       pick_next_task kernel/sched/core.c:6338 [inline]
       __schedule+0x388e/0x56c0 kernel/sched/core.c:7149
       preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7413
       preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12
       __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:188 [inline]
       _raw_spin_unlock_irq+0x45/0x50 kernel/locking/spinlock.c:206
       spin_unlock_irq include/linux/spinlock.h:402 [inline]
       signalfd_dequeue fs/signalfd.c:170 [inline]
       signalfd_read_iter+0x301/0xa00 fs/signalfd.c:216
       new_sync_read fs/read_write.c:493 [inline]
       vfs_read+0x595/0xa80 fs/read_write.c:574
       ksys_read+0x150/0x270 fs/read_write.c:716
       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 --> &p->pi_lock --> &rq->__lock

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

3 locks held by syz.5.1376/10600:
 #0: ffff8880b863b160 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xb2/0x160 kernel/sched/core.c:675
 #1: ffffffff8eb4bfa0 (console_lock){+.+.}-{0:0}, at: _printk+0xdd/0x130 kernel/printk/printk.c:2504
 #2: ffffffff8ea33838 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:305 [inline]
 #2: ffffffff8ea33838 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline]
 #2: ffffffff8ea33838 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline]
 #2: ffffffff8ea33838 (console_srcu){....}-{0:0}, at: console_flush_one_record kernel/printk/printk.c:3246 [inline]
 #2: ffffffff8ea33838 (console_srcu){....}-{0:0}, at: console_flush_all+0x123/0xaf0 kernel/printk/printk.c:3343

stack backtrace:
CPU: 0 UID: 0 PID: 10600 Comm: syz.5.1376 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 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
 __report_bug+0x349/0x570 lib/bug.c:248
 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:lockdep_assert_rq_held kernel/sched/sched.h:1641 [inline]
RIP: 0010:update_rq_clock+0x34d/0x560 kernel/sched/core.c:865
Code: 48 c1 e8 03 80 3c 28 00 74 08 48 89 df e8 fb 1a a0 00 4c 01 3b 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d e9 60 be 7b ff cc 90 <0f> 0b 90 e9 42 fd ff ff 48 89 df 48 83 c4 10 5b 41 5c 41 5d 41 5e
RSP: 0018:ffffc9000d4e7798 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8880b873b100 RCX: 0000000000000002
RDX: 0000000000000000 RSI: ffffffff8e4adf3a RDI: ffffffff8c4bbf80
RBP: dffffc0000000000 R08: ffffffff90574837 R09: 1ffffffff20ae906
R10: dffffc0000000000 R11: ffffffff819fde60 R12: ffff888031dd07e8
R13: dffffc0000000001 R14: ffff8880b873bfc8 R15: ffff8880b873b100
 pick_next_task kernel/sched/core.c:6338 [inline]
 __schedule+0x388e/0x56c0 kernel/sched/core.c:7149
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7413
 preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:188 [inline]
 _raw_spin_unlock_irq+0x45/0x50 kernel/locking/spinlock.c:206
 spin_unlock_irq include/linux/spinlock.h:402 [inline]
 signalfd_dequeue fs/signalfd.c:170 [inline]
 signalfd_read_iter+0x301/0xa00 fs/signalfd.c:216
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x595/0xa80 fs/read_write.c:574
 ksys_read+0x150/0x270 fs/read_write.c:716
 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: 0033:0x7ff09d79e0d9
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:00007ff09b9f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007ff09da25fa0 RCX: 00007ff09d79e0d9
RDX: 00000000fffffef0 RSI: 00002000000008c0 RDI: 0000000000000005
RBP: 00007ff09d835024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff09da26038 R14: 00007ff09da25fa0 R15: 00007fff057caf68
 </TASK>
debug_locks && !(lock_is_held(&(__rq_lockp(rq))->dep_map) != 0)
WARNING: kernel/sched/sched.h:1641 at lockdep_assert_rq_held kernel/sched/sched.h:1641 [inline], CPU#0: syz.5.1376/10600
WARNING: kernel/sched/sched.h:1641 at update_rq_clock+0x34d/0x560 kernel/sched/core.c:865, CPU#0: syz.5.1376/10600
Modules linked in:
CPU: 0 UID: 0 PID: 10600 Comm: syz.5.1376 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:lockdep_assert_rq_held kernel/sched/sched.h:1641 [inline]
RIP: 0010:update_rq_clock+0x34d/0x560 kernel/sched/core.c:865
Code: 48 c1 e8 03 80 3c 28 00 74 08 48 89 df e8 fb 1a a0 00 4c 01 3b 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d e9 60 be 7b ff cc 90 <0f> 0b 90 e9 42 fd ff ff 48 89 df 48 83 c4 10 5b 41 5c 41 5d 41 5e
RSP: 0018:ffffc9000d4e7798 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8880b873b100 RCX: 0000000000000002
RDX: 0000000000000000 RSI: ffffffff8e4adf3a RDI: ffffffff8c4bbf80
RBP: dffffc0000000000 R08: ffffffff90574837 R09: 1ffffffff20ae906
R10: dffffc0000000000 R11: ffffffff819fde60 R12: ffff888031dd07e8
R13: dffffc0000000001 R14: ffff8880b873bfc8 R15: ffff8880b873b100
FS:  00007ff09b9f66c0(0000) GS:ffff888124f55000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000020000000a000 CR3: 00000000761bd000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 pick_next_task kernel/sched/core.c:6338 [inline]
 __schedule+0x388e/0x56c0 kernel/sched/core.c:7149
 preempt_schedule_common+0x82/0xd0 kernel/sched/core.c:7413
 preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:188 [inline]
 _raw_spin_unlock_irq+0x45/0x50 kernel/locking/spinlock.c:206
 spin_unlock_irq include/linux/spinlock.h:402 [inline]
 signalfd_dequeue fs/signalfd.c:170 [inline]
 signalfd_read_iter+0x301/0xa00 fs/signalfd.c:216
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x595/0xa80 fs/read_write.c:574
 ksys_read+0x150/0x270 fs/read_write.c:716
 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: 0033:0x7ff09d79e0d9
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:00007ff09b9f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007ff09da25fa0 RCX: 00007ff09d79e0d9
RDX: 00000000fffffef0 RSI: 00002000000008c0 RDI: 0000000000000005
RBP: 00007ff09d835024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff09da26038 R14: 00007ff09da25fa0 R15: 00007fff057caf68
 </TASK>