------------[ cut here ]------------
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G             L     
------------------------------------------------------
syz.6.1427/11746 is trying to acquire lock:
ffffffff8eb4c040 (console_owner){..-.}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:305 [inline]
ffffffff8eb4c040 (console_owner){..-.}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline]
ffffffff8eb4c040 (console_owner){..-.}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline]
ffffffff8eb4c040 (console_owner){..-.}-{0:0}, at: console_flush_one_record kernel/printk/printk.c:3246 [inline]
ffffffff8eb4c040 (console_owner){..-.}-{0:0}, at: console_flush_all+0x123/0xaf0 kernel/printk/printk.c:3343

but task is already holding lock:
ffff8880b863b360 (&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+0x4062/0x43e0 kernel/fork.c:2568
       kernel_clone+0x2d7/0x940 kernel/fork.c:2766
       rest_init+0xbf/0x3a0 init/main.c:688
       start_kernel+0x392/0x3e0 init/main.c:1181
       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
       pty_unthrottle+0x3c/0x60 drivers/tty/pty.c:93
       tty_unthrottle_safe+0x111/0x160 drivers/tty/tty_ioctl.c:163
       n_tty_receive_buf_common+0x100c/0x13d0 drivers/tty/n_tty.c:1730
       tty_port_default_receive_buf+0x6e/0xa0 drivers/tty/tty_port.c:37
       receive_buf drivers/tty/tty_buffer.c:452 [inline]
       flush_to_ldisc+0x247/0x6c0 drivers/tty/tty_buffer.c:502
       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
       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+0x1cc/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:1118
       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 include/linux/spinlock_api_smp.h:169 [inline]
       _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:190
       spin_unlock include/linux/spinlock.h:390 [inline]
       filemap_remove_folio+0x1b4/0x3a0 mm/filemap.c:261
       truncate_inode_folio+0x5d/0x70 mm/truncate.c:176
       shmem_undo_range+0x3fb/0x15d0 mm/shmem.c:1155
       shmem_truncate_range mm/shmem.c:1287 [inline]
       shmem_evict_inode+0x280/0xa80 mm/shmem.c:1417
       evict+0x624/0xb50 fs/inode.c:822
       dentry_kill+0x1b9/0x880 fs/dcache.c:826
       finish_dput+0x1a/0x260 fs/dcache.c:1001
       __fput+0x675/0xa50 fs/file_table.c:520
       task_work_run+0x1d9/0x270 kernel/task_work.c:233
       exit_task_work include/linux/task_work.h:40 [inline]
       do_exit+0x73a/0x2360 kernel/exit.c:1009
       do_group_exit+0x22d/0x2f0 kernel/exit.c:1152
       get_signal+0x121b/0x12c0 kernel/signal.c:3046
       arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
       __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
       exit_to_user_mode_loop kernel/entry/common.c:101 [inline]
       __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
       irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:244 [inline]
       irqentry_exit_to_user_mode include/linux/irq-entry-common.h:315 [inline]
       irqentry_exit+0x2ba/0x910 kernel/entry/common.c:165
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595

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.6.1427/11746:
 #0: ffff8880b863b360 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xb2/0x160 kernel/sched/core.c:675
 #1: ffffffff8eb4c0a0 (console_lock){+.+.}-{0:0}, at: _printk+0xdd/0x130 kernel/printk/printk.c:2504
 #2: ffffffff8ea33938 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:305 [inline]
 #2: ffffffff8ea33938 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:428 [inline]
 #2: ffffffff8ea33938 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:291 [inline]
 #2: ffffffff8ea33938 (console_srcu){....}-{0:0}, at: console_flush_one_record kernel/printk/printk.c:3246 [inline]
 #2: ffffffff8ea33938 (console_srcu){....}-{0:0}, at: console_flush_all+0x123/0xaf0 kernel/printk/printk.c:3343

stack backtrace:
CPU: 0 UID: 0 PID: 11746 Comm: syz.6.1427 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 cb 28 a0 00 4c 01 3b 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d e9 20 bd 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:ffffc90003ea6ff8 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8880b873b300 RCX: 0000000000000002
RDX: 0000000000000000 RSI: ffffffff8e4b3e80 RDI: ffffffff8c4bdc80
RBP: dffffc0000000000 R08: ffffffff90579f37 R09: 1ffffffff20af3e6
R10: dffffc0000000000 R11: ffffffff819fdfa0 R12: ffff8880292d65a8
R13: dffffc0000000001 R14: ffff8880b873c1c8 R15: ffff8880b873b300
 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 include/linux/spinlock_api_smp.h:169 [inline]
 _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:190
 spin_unlock include/linux/spinlock.h:390 [inline]
 filemap_remove_folio+0x1b4/0x3a0 mm/filemap.c:261
 truncate_inode_folio+0x5d/0x70 mm/truncate.c:176
 shmem_undo_range+0x3fb/0x15d0 mm/shmem.c:1155
 shmem_truncate_range mm/shmem.c:1287 [inline]
 shmem_evict_inode+0x280/0xa80 mm/shmem.c:1417
 evict+0x624/0xb50 fs/inode.c:822
 dentry_kill+0x1b9/0x880 fs/dcache.c:826
 finish_dput+0x1a/0x260 fs/dcache.c:1001
 __fput+0x675/0xa50 fs/file_table.c:520
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x73a/0x2360 kernel/exit.c:1009
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1152
 get_signal+0x121b/0x12c0 kernel/signal.c:3046
 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:101 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:244 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:315 [inline]
 irqentry_exit+0x2ba/0x910 kernel/entry/common.c:165
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
RIP: 0033:0x7f2f65f9e0e1
Code: Unable to access opcode bytes at 0x7f2f65f9e0b7.
RSP: 002b:fffffffffffffe70 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f2f66226090 RCX: 00007f2f65f9e0d9
RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000
RBP: 00007f2f66035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f2f66226128 R14: 00007f2f66226090 R15: 00007ffdb8d332c8
 </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.6.1427/11746
WARNING: kernel/sched/sched.h:1641 at update_rq_clock+0x34d/0x560 kernel/sched/core.c:865, CPU#0: syz.6.1427/11746
Modules linked in:
CPU: 0 UID: 0 PID: 11746 Comm: syz.6.1427 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 cb 28 a0 00 4c 01 3b 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d e9 20 bd 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:ffffc90003ea6ff8 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8880b873b300 RCX: 0000000000000002
RDX: 0000000000000000 RSI: ffffffff8e4b3e80 RDI: ffffffff8c4bdc80
RBP: dffffc0000000000 R08: ffffffff90579f37 R09: 1ffffffff20af3e6
R10: dffffc0000000000 R11: ffffffff819fdfa0 R12: ffff8880292d65a8
R13: dffffc0000000001 R14: ffff8880b873c1c8 R15: ffff8880b873b300
FS:  0000000000000000(0000) GS:ffff888124f3f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9118b23ff8 CR3: 0000000077960000 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 include/linux/spinlock_api_smp.h:169 [inline]
 _raw_spin_unlock+0x3f/0x50 kernel/locking/spinlock.c:190
 spin_unlock include/linux/spinlock.h:390 [inline]
 filemap_remove_folio+0x1b4/0x3a0 mm/filemap.c:261
 truncate_inode_folio+0x5d/0x70 mm/truncate.c:176
 shmem_undo_range+0x3fb/0x15d0 mm/shmem.c:1155
 shmem_truncate_range mm/shmem.c:1287 [inline]
 shmem_evict_inode+0x280/0xa80 mm/shmem.c:1417
 evict+0x624/0xb50 fs/inode.c:822
 dentry_kill+0x1b9/0x880 fs/dcache.c:826
 finish_dput+0x1a/0x260 fs/dcache.c:1001
 __fput+0x675/0xa50 fs/file_table.c:520
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x73a/0x2360 kernel/exit.c:1009
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1152
 get_signal+0x121b/0x12c0 kernel/signal.c:3046
 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:101 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:244 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:315 [inline]
 irqentry_exit+0x2ba/0x910 kernel/entry/common.c:165
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595
RIP: 0033:0x7f2f65f9e0e1
Code: Unable to access opcode bytes at 0x7f2f65f9e0b7.
RSP: 002b:fffffffffffffe70 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007f2f66226090 RCX: 00007f2f65f9e0d9
RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000
RBP: 00007f2f66035024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f2f66226128 R14: 00007f2f66226090 R15: 00007ffdb8d332c8
 </TASK>