FAULT_INJECTION: forcing a failure.
name fail_usercopy, interval 1, probability 0, space 0, times 0
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.8.1734/12204 is trying to acquire lock:
ffffffff8c91f3a0 (console_owner){-.-.}-{0:0}, at: console_lock_spinning_enable kernel/printk/printk.c:1818 [inline]
ffffffff8c91f3a0 (console_owner){-.-.}-{0:0}, at: console_emit_next_record+0x82d/0xc90 kernel/printk/printk.c:2774

but task is already holding lock:
ffff8880b8e3ab18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xa5/0x140 kernel/sched/core.c:546

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+0x2e/0x40 kernel/locking/spinlock.c:378
       raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:538
       raw_spin_rq_lock kernel/sched/sched.h:1362 [inline]
       rq_lock kernel/sched/sched.h:1652 [inline]
       task_fork_fair+0x5c/0x350 kernel/sched/fair.c:11928
       sched_cgroup_fork+0x32c/0x3c0 kernel/sched/core.c:4686
       copy_process+0x24b8/0x4020 kernel/fork.c:2464
       kernel_clone+0x225/0x8b0 kernel/fork.c:2762
       user_mode_thread+0xda/0x130 kernel/fork.c:2838
       rest_init+0x23/0x300 init/main.c:710
       start_kernel+0x0/0x539 init/main.c:905
       start_kernel+0x490/0x539 init/main.c:1152
       secondary_startup_64_no_verify+0xcf/0xdb

-> #3 (&p->pi_lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
       try_to_wake_up+0x5c/0x1080 kernel/sched/core.c:4112
       __wake_up_common+0x2a4/0x4e0 kernel/sched/wait.c:107
       __wake_up_common_lock kernel/sched/wait.c:138 [inline]
       __wake_up+0x10e/0x190 kernel/sched/wait.c:160
       pty_close+0x265/0x440 drivers/tty/pty.c:68
       tty_release+0x383/0x1600 drivers/tty/tty_io.c:1753
       __fput+0x22c/0x920 fs/file_table.c:320
       task_work_run+0x1ca/0x250 kernel/task_work.c:203
       resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
       exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
       exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
       __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
       syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
       do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #2 (&tty->write_wait){-...}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa4/0xf0 kernel/locking/spinlock.c:162
       __wake_up_common_lock kernel/sched/wait.c:137 [inline]
       __wake_up+0xf4/0x190 kernel/sched/wait.c:160
       tty_port_default_wakeup+0x9e/0xf0 drivers/tty/tty_port.c:71
       serial8250_tx_chars+0x629/0x830 drivers/tty/serial/8250/8250_port.c:1854
       serial8250_handle_irq+0x516/0x6d0 drivers/tty/serial/8250/8250_port.c:1961
       serial8250_default_handle_irq+0xb4/0x1a0 drivers/tty/serial/8250/8250_port.c:1981
       serial8250_interrupt+0x9b/0x1c0 drivers/tty/serial/8250/8250_core.c:126
       __handle_irq_event_percpu+0x298/0xa30 kernel/irq/handle.c:158
       handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
       handle_irq_event+0x87/0x1e0 kernel/irq/handle.c:210
       handle_edge_irq+0x243/0xb20 kernel/irq/chip.c:819
       generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
       handle_irq arch/x86/kernel/irq.c:233 [inline]
       __common_interrupt+0xd7/0x1e0 arch/x86/kernel/irq.c:252
       common_interrupt+0xb0/0xd0 arch/x86/kernel/irq.c:242
       asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:682
       __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
       _raw_spin_unlock_irqrestore+0xa5/0x100 kernel/locking/spinlock.c:194
       spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
       uart_write+0x68a/0x910 drivers/tty/serial/serial_core.c:602
       process_output_block drivers/tty/n_tty.c:586 [inline]
       n_tty_write+0xd1a/0x11c0 drivers/tty/n_tty.c:2377
       do_tty_write drivers/tty/tty_io.c:1018 [inline]
       file_tty_write+0x4dd/0x860 drivers/tty/tty_io.c:1089
       call_write_iter include/linux/fs.h:2265 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x44c/0x960 fs/read_write.c:584
       ksys_write+0x143/0x240 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x4c/0xa0 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+0xa4/0xf0 kernel/locking/spinlock.c:162
       serial8250_console_write+0x169/0x17a0 drivers/tty/serial/8250/8250_port.c:3432
       call_console_driver kernel/printk/printk.c:1977 [inline]
       console_emit_next_record+0x947/0xc90 kernel/printk/printk.c:2777
       console_flush_all kernel/printk/printk.c:-1 [inline]
       console_unlock+0x223/0x630 kernel/printk/printk.c:2906
       vprintk_emit+0x489/0x680 kernel/printk/printk.c:2303
       _printk+0xcc/0x110 kernel/printk/printk.c:2328
       register_console+0x6c6/0x9c0 kernel/printk/printk.c:3269
       univ8250_console_init+0x41/0x43 drivers/tty/serial/8250/8250_core.c:687
       console_init+0x1bc/0x78e kernel/printk/printk.c:3359
       start_kernel+0x303/0x539 init/main.c:1088
       secondary_startup_64_no_verify+0xcf/0xdb

-> #0 (console_owner){-.-.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
       lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
       console_lock_spinning_enable kernel/printk/printk.c:1818 [inline]
       console_emit_next_record+0x84c/0xc90 kernel/printk/printk.c:2774
       console_flush_all kernel/printk/printk.c:-1 [inline]
       console_unlock+0x223/0x630 kernel/printk/printk.c:2906
       vprintk_emit+0x489/0x680 kernel/printk/printk.c:2303
       _printk+0xcc/0x110 kernel/printk/printk.c:2328
       fail_dump lib/fault-inject.c:45 [inline]
       should_fail_ex+0x37a/0x4d0 lib/fault-inject.c:147
       strncpy_from_user+0x32/0x350 lib/strncpy_from_user.c:118
       strncpy_from_user_nofault+0x6d/0x140 mm/maccess.c:186
       bpf_trace_copy_string kernel/bpf/helpers.c:746 [inline]
       bpf_bprintf_prepare+0xba0/0x13d0 kernel/bpf/helpers.c:971
       ____bpf_trace_printk kernel/trace/bpf_trace.c:384 [inline]
       bpf_trace_printk+0xd8/0x190 kernel/trace/bpf_trace.c:374
       bpf_prog_7c77c7e0f6645ad8+0x35/0x37
       bpf_dispatcher_nop_func include/linux/bpf.h:1012 [inline]
       __bpf_prog_run include/linux/filter.h:607 [inline]
       bpf_prog_run include/linux/filter.h:614 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2285 [inline]
       bpf_trace_run2+0x1cd/0x3d0 kernel/trace/bpf_trace.c:2324
       trace_contention_begin+0x142/0x190 include/trace/events/lock.h:95
       __pv_queued_spin_lock_slowpath+0xdc/0x9c0 kernel/locking/qspinlock.c:405
       pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline]
       queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51
       queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
       do_raw_spin_lock+0x217/0x280 kernel/locking/spinlock_debug.c:115
       raw_spin_rq_lock_nested+0xa5/0x140 kernel/sched/core.c:546
       raw_spin_rq_lock kernel/sched/sched.h:1362 [inline]
       rq_lock kernel/sched/sched.h:1652 [inline]
       __schedule+0x2ed/0x40b0 kernel/sched/core.c:6478
       preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6874
       irqentry_exit+0x63/0x70 kernel/entry/common.c:439
       asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696
       exit_to_user_mode_loop+0x40/0x110 kernel/entry/common.c:164
       exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
       __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
       syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
       do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

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.8.1734/12204:
 #0: ffff8880b8e3ab18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xa5/0x140 kernel/sched/core.c:546
 #1: ffffffff8c92b1e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #1: ffffffff8c92b1e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #1: ffffffff8c92b1e0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline]
 #1: ffffffff8c92b1e0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0xda/0x3d0 kernel/trace/bpf_trace.c:2324
 #2: ffffffff8c91f480 (console_lock){+.+.}-{0:0}, at: _printk+0xcc/0x110 kernel/printk/printk.c:2328

stack backtrace:
CPU: 1 PID: 12204 Comm: syz.8.1734 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 check_noncircular+0x274/0x310 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 console_lock_spinning_enable kernel/printk/printk.c:1818 [inline]
 console_emit_next_record+0x84c/0xc90 kernel/printk/printk.c:2774
 console_flush_all kernel/printk/printk.c:-1 [inline]
 console_unlock+0x223/0x630 kernel/printk/printk.c:2906
 vprintk_emit+0x489/0x680 kernel/printk/printk.c:2303
 _printk+0xcc/0x110 kernel/printk/printk.c:2328
 fail_dump lib/fault-inject.c:45 [inline]
 should_fail_ex+0x37a/0x4d0 lib/fault-inject.c:147
 strncpy_from_user+0x32/0x350 lib/strncpy_from_user.c:118
 strncpy_from_user_nofault+0x6d/0x140 mm/maccess.c:186
 bpf_trace_copy_string kernel/bpf/helpers.c:746 [inline]
 bpf_bprintf_prepare+0xba0/0x13d0 kernel/bpf/helpers.c:971
 ____bpf_trace_printk kernel/trace/bpf_trace.c:384 [inline]
 bpf_trace_printk+0xd8/0x190 kernel/trace/bpf_trace.c:374
 bpf_prog_7c77c7e0f6645ad8+0x35/0x37
 bpf_dispatcher_nop_func include/linux/bpf.h:1012 [inline]
 __bpf_prog_run include/linux/filter.h:607 [inline]
 bpf_prog_run include/linux/filter.h:614 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2285 [inline]
 bpf_trace_run2+0x1cd/0x3d0 kernel/trace/bpf_trace.c:2324
 trace_contention_begin+0x142/0x190 include/trace/events/lock.h:95
 __pv_queued_spin_lock_slowpath+0xdc/0x9c0 kernel/locking/qspinlock.c:405
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline]
 queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x217/0x280 kernel/locking/spinlock_debug.c:115
 raw_spin_rq_lock_nested+0xa5/0x140 kernel/sched/core.c:546
 raw_spin_rq_lock kernel/sched/sched.h:1362 [inline]
 rq_lock kernel/sched/sched.h:1652 [inline]
 __schedule+0x2ed/0x40b0 kernel/sched/core.c:6478
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6874
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696
RIP: 0010:exit_to_user_mode_loop+0x40/0x110 kernel/entry/common.c:164
Code: fb eb 1d e8 d2 2f a3 08 65 48 8b 05 da 5d 94 7e 4c 8b 30 41 f7 c6 0e 30 02 00 0f 84 c4 00 00 00 e8 65 54 19 00 fb 41 f6 c6 08 <74> 05 e8 09 b1 ab 08 41 f7 c6 00 10 00 00 74 08 48 89 df e8 28 4a
RSP: 0018:ffffc90010befed0 EFLAGS: 00000202
RAX: cb20e59397d70400 RBX: ffffc90010beff58 RCX: cb20e59397d70400
RDX: dffffc0000000000 RSI: ffffffff8a6c0600 RDI: ffffffff8abefec0
RBP: ffffc90010beff48 R08: dffffc0000000000 R09: ffffed100fa161ef
R10: ffffed100fa161ef R11: 1ffff1100fa161ee R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000004008 R15: ffff888077ea8000
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f365d18e1ff
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48
RSP: 002b:00007f365df59030 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: 0000000000000001 RBX: 0000000000000006 RCX: 00007f365d18e1ff
RDX: 0000000000000001 RSI: 00007f365df59090 RDI: 0000000000000006
RBP: 00007f365df59090 R08: 0000000000000000 R09: 00007f365df58df7
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 00007f365d3e6218 R14: 00007f365d3e6180 R15: 00007fff2d294788
 </TASK>
CPU: 1 PID: 12204 Comm: syz.8.1734 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail_ex+0x399/0x4d0 lib/fault-inject.c:147
 strncpy_from_user+0x32/0x350 lib/strncpy_from_user.c:118
 strncpy_from_user_nofault+0x6d/0x140 mm/maccess.c:186
 bpf_trace_copy_string kernel/bpf/helpers.c:746 [inline]
 bpf_bprintf_prepare+0xba0/0x13d0 kernel/bpf/helpers.c:971
 ____bpf_trace_printk kernel/trace/bpf_trace.c:384 [inline]
 bpf_trace_printk+0xd8/0x190 kernel/trace/bpf_trace.c:374
 bpf_prog_7c77c7e0f6645ad8+0x35/0x37
 bpf_dispatcher_nop_func include/linux/bpf.h:1012 [inline]
 __bpf_prog_run include/linux/filter.h:607 [inline]
 bpf_prog_run include/linux/filter.h:614 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2285 [inline]
 bpf_trace_run2+0x1cd/0x3d0 kernel/trace/bpf_trace.c:2324
 trace_contention_begin+0x142/0x190 include/trace/events/lock.h:95
 __pv_queued_spin_lock_slowpath+0xdc/0x9c0 kernel/locking/qspinlock.c:405
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:591 [inline]
 queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x217/0x280 kernel/locking/spinlock_debug.c:115
 raw_spin_rq_lock_nested+0xa5/0x140 kernel/sched/core.c:546
 raw_spin_rq_lock kernel/sched/sched.h:1362 [inline]
 rq_lock kernel/sched/sched.h:1652 [inline]
 __schedule+0x2ed/0x40b0 kernel/sched/core.c:6478
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6874
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:696
RIP: 0010:exit_to_user_mode_loop+0x40/0x110 kernel/entry/common.c:164
Code: fb eb 1d e8 d2 2f a3 08 65 48 8b 05 da 5d 94 7e 4c 8b 30 41 f7 c6 0e 30 02 00 0f 84 c4 00 00 00 e8 65 54 19 00 fb 41 f6 c6 08 <74> 05 e8 09 b1 ab 08 41 f7 c6 00 10 00 00 74 08 48 89 df e8 28 4a
RSP: 0018:ffffc90010befed0 EFLAGS: 00000202
RAX: cb20e59397d70400 RBX: ffffc90010beff58 RCX: cb20e59397d70400
RDX: dffffc0000000000 RSI: ffffffff8a6c0600 RDI: ffffffff8abefec0
RBP: ffffc90010beff48 R08: dffffc0000000000 R09: ffffed100fa161ef
R10: ffffed100fa161ef R11: 1ffff1100fa161ee R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000004008 R15: ffff888077ea8000
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f365d18e1ff
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 f9 92 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 4c 93 02 00 48
RSP: 002b:00007f365df59030 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: 0000000000000001 RBX: 0000000000000006 RCX: 00007f365d18e1ff
RDX: 0000000000000001 RSI: 00007f365df59090 RDI: 0000000000000006
RBP: 00007f365df59090 R08: 0000000000000000 R09: 00007f365df58df7
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 00007f365d3e6218 R14: 00007f365d3e6180 R15: 00007fff2d294788
 </TASK>
----------------
Code disassembly (best guess):
   0:	fb                   	sti
   1:	eb 1d                	jmp    0x20
   3:	e8 d2 2f a3 08       	call   0x8a32fda
   8:	65 48 8b 05 da 5d 94 	mov    %gs:0x7e945dda(%rip),%rax        # 0x7e945dea
   f:	7e
  10:	4c 8b 30             	mov    (%rax),%r14
  13:	41 f7 c6 0e 30 02 00 	test   $0x2300e,%r14d
  1a:	0f 84 c4 00 00 00    	je     0xe4
  20:	e8 65 54 19 00       	call   0x19548a
  25:	fb                   	sti
  26:	41 f6 c6 08          	test   $0x8,%r14b
* 2a:	74 05                	je     0x31 <-- trapping instruction
  2c:	e8 09 b1 ab 08       	call   0x8abb13a
  31:	41 f7 c6 00 10 00 00 	test   $0x1000,%r14d
  38:	74 08                	je     0x42
  3a:	48 89 df             	mov    %rbx,%rdi
  3d:	e8                   	.byte 0xe8
  3e:	28                   	.byte 0x28
  3f:	4a                   	rex.WX