FAULT_INJECTION: forcing a failure.
name fail_usercopy, interval 1, probability 0, space 0, times 0
======================================================
WARNING: possible circular locking dependency detected
6.1.135-syzkaller #0 Not tainted
------------------------------------------------------
syz.1.3041/14518 is trying to acquire lock:
ffffffff8c91eb80 (console_owner){-...}-{0:0}, at: console_lock_spinning_enable kernel/printk/printk.c:1818 [inline]
ffffffff8c91eb80 (console_owner){-...}-{0:0}, at: console_emit_next_record+0x82d/0xc90 kernel/printk/printk.c:2774

but task is already holding lock:
ffff8880b8f3aa58 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:537

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:537
       raw_spin_rq_lock kernel/sched/sched.h:1355 [inline]
       rq_lock kernel/sched/sched.h:1645 [inline]
       task_fork_fair+0x5c/0x350 kernel/sched/fair.c:11888
       sched_cgroup_fork+0x32c/0x3c0 kernel/sched/core.c:4685
       copy_process+0x248b/0x4060 kernel/fork.c:2383
       kernel_clone+0x225/0x8b0 kernel/fork.c:2681
       user_mode_thread+0xda/0x130 kernel/fork.c:2757
       rest_init+0x23/0x300 init/main.c:698
       start_kernel+0x0/0x539 init/main.c:893
       start_kernel+0x490/0x539 init/main.c:1140
       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:4111
       __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
       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
       check_kcov_mode kernel/kcov.c:184 [inline]
       write_comp_data kernel/kcov.c:245 [inline]
       __sanitizer_cov_trace_const_cmp8+0x32/0x80 kernel/kcov.c:320
       new_sync_write fs/read_write.c:493 [inline]
       vfs_write+0x478/0x960 fs/read_write.c:584
       ksys_write+0x143/0x240 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       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:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       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:3433
       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:1076
       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_probe_read_user_str_common kernel/trace/bpf_trace.c:204 [inline]
       ____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:310 [inline]
       bpf_probe_read_compat_str+0xdd/0x170 kernel/trace/bpf_trace.c:306
       bpf_prog_c1796171ffc7efef+0x35/0x37
       bpf_dispatcher_nop_func include/linux/bpf.h:1001 [inline]
       __bpf_prog_run include/linux/filter.h:603 [inline]
       bpf_prog_run include/linux/filter.h:610 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline]
       bpf_trace_run4+0x1f5/0x420 kernel/trace/bpf_trace.c:2325
       __traceiter_sched_switch+0x8f/0xc0 include/trace/events/sched.h:222
       trace_sched_switch include/trace/events/sched.h:222 [inline]
       __schedule+0x1d32/0x40d0 kernel/sched/core.c:6558
       preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
       irqentry_exit+0x63/0x70 kernel/entry/common.c:439
       asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
       get_current arch/x86/include/asm/current.h:15 [inline]
       __syscall_enter_from_user_work kernel/entry/common.c:97 [inline]
       syscall_enter_from_user_mode+0x2a/0x80 kernel/entry/common.c:118
       do_syscall_64+0x24/0xa0 arch/x86/entry/common.c:77
       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.1.3041/14518:
 #0: ffff8880b8f3aa58 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x26/0x140 kernel/sched/core.c:537
 #1: ffffffff8c92a9e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #1: ffffffff8c92a9e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #1: ffffffff8c92a9e0 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2283 [inline]
 #1: ffffffff8c92a9e0 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run4+0xf9/0x420 kernel/trace/bpf_trace.c:2325
 #2: ffffffff8c91ec60 (console_lock){+.+.}-{0:0}, at: _printk+0xcc/0x110 kernel/printk/printk.c:2328

stack backtrace:
CPU: 1 PID: 14518 Comm: syz.1.3041 Not tainted 6.1.135-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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_probe_read_user_str_common kernel/trace/bpf_trace.c:204 [inline]
 ____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:310 [inline]
 bpf_probe_read_compat_str+0xdd/0x170 kernel/trace/bpf_trace.c:306
 bpf_prog_c1796171ffc7efef+0x35/0x37
 bpf_dispatcher_nop_func include/linux/bpf.h:1001 [inline]
 __bpf_prog_run include/linux/filter.h:603 [inline]
 bpf_prog_run include/linux/filter.h:610 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline]
 bpf_trace_run4+0x1f5/0x420 kernel/trace/bpf_trace.c:2325
 __traceiter_sched_switch+0x8f/0xc0 include/trace/events/sched.h:222
 trace_sched_switch include/trace/events/sched.h:222 [inline]
 __schedule+0x1d32/0x40d0 kernel/sched/core.c:6558
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__syscall_enter_from_user_work kernel/entry/common.c:97 [inline]
RIP: 0010:syscall_enter_from_user_mode+0x2a/0x80 kernel/entry/common.c:118
Code: 41 56 53 48 89 f3 49 89 fe 48 8b 7c 24 10 e8 ed fa ff ff 66 90 66 90 e8 24 29 78 f7 e8 9f 27 78 f7 fb 65 48 8b 05 a6 77 f3 75 <48> 8b 70 08 40 f6 c6 3f 74 0b 4c 89 f7 5b 41 5e e9 71 c0 5e f7 48
RSP: 0018:ffffc90003667f08 EFLAGS: 00000286
RAX: ffff888030718000 RBX: 0000000000000001 RCX: 9b34cb49ef77cb00
RDX: dffffc0000000000 RSI: ffffffff8a6bff00 RDI: ffffffff8abf0ea0
RBP: ffffc90003667f48 R08: dffffc0000000000 R09: fffffbfff1bfcf4e
R10: fffffbfff1bfcf4e R11: 1ffffffff1bfcf4d R12: 0000000000000000
R13: 0000000000000000 R14: ffffc90003667f58 R15: 0000000000000000
 do_syscall_64+0x24/0xa0 arch/x86/entry/common.c:77
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f57ff98e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5800784038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f57ffbb5fa0 RCX: 00007f57ff98e969
RDX: 0000000000033fe0 RSI: 0000200000000000 RDI: 0000000000000006
RBP: 00007f5800784090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f57ffbb5fa0 R15: 00007fff350a3598
 </TASK>
CPU: 1 PID: 14518 Comm: syz.1.3041 Not tainted 6.1.135-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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_probe_read_user_str_common kernel/trace/bpf_trace.c:204 [inline]
 ____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:310 [inline]
 bpf_probe_read_compat_str+0xdd/0x170 kernel/trace/bpf_trace.c:306
 bpf_prog_c1796171ffc7efef+0x35/0x37
 bpf_dispatcher_nop_func include/linux/bpf.h:1001 [inline]
 __bpf_prog_run include/linux/filter.h:603 [inline]
 bpf_prog_run include/linux/filter.h:610 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2284 [inline]
 bpf_trace_run4+0x1f5/0x420 kernel/trace/bpf_trace.c:2325
 __traceiter_sched_switch+0x8f/0xc0 include/trace/events/sched.h:222
 trace_sched_switch include/trace/events/sched.h:222 [inline]
 __schedule+0x1d32/0x40d0 kernel/sched/core.c:6558
 preempt_schedule_irq+0xb1/0x150 kernel/sched/core.c:6873
 irqentry_exit+0x63/0x70 kernel/entry/common.c:439
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__syscall_enter_from_user_work kernel/entry/common.c:97 [inline]
RIP: 0010:syscall_enter_from_user_mode+0x2a/0x80 kernel/entry/common.c:118
Code: 41 56 53 48 89 f3 49 89 fe 48 8b 7c 24 10 e8 ed fa ff ff 66 90 66 90 e8 24 29 78 f7 e8 9f 27 78 f7 fb 65 48 8b 05 a6 77 f3 75 <48> 8b 70 08 40 f6 c6 3f 74 0b 4c 89 f7 5b 41 5e e9 71 c0 5e f7 48
RSP: 0018:ffffc90003667f08 EFLAGS: 00000286
RAX: ffff888030718000 RBX: 0000000000000001 RCX: 9b34cb49ef77cb00
RDX: dffffc0000000000 RSI: ffffffff8a6bff00 RDI: ffffffff8abf0ea0
RBP: ffffc90003667f48 R08: dffffc0000000000 R09: fffffbfff1bfcf4e
R10: fffffbfff1bfcf4e R11: 1ffffffff1bfcf4d R12: 0000000000000000
R13: 0000000000000000 R14: ffffc90003667f58 R15: 0000000000000000
 do_syscall_64+0x24/0xa0 arch/x86/entry/common.c:77
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f57ff98e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5800784038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f57ffbb5fa0 RCX: 00007f57ff98e969
RDX: 0000000000033fe0 RSI: 0000200000000000 RDI: 0000000000000006
RBP: 00007f5800784090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f57ffbb5fa0 R15: 00007fff350a3598
 </TASK>
----------------
Code disassembly (best guess):
   0:	41 56                	push   %r14
   2:	53                   	push   %rbx
   3:	48 89 f3             	mov    %rsi,%rbx
   6:	49 89 fe             	mov    %rdi,%r14
   9:	48 8b 7c 24 10       	mov    0x10(%rsp),%rdi
   e:	e8 ed fa ff ff       	call   0xfffffb00
  13:	66 90                	xchg   %ax,%ax
  15:	66 90                	xchg   %ax,%ax
  17:	e8 24 29 78 f7       	call   0xf7782940
  1c:	e8 9f 27 78 f7       	call   0xf77827c0
  21:	fb                   	sti
  22:	65 48 8b 05 a6 77 f3 	mov    %gs:0x75f377a6(%rip),%rax        # 0x75f377d0
  29:	75
* 2a:	48 8b 70 08          	mov    0x8(%rax),%rsi <-- trapping instruction
  2e:	40 f6 c6 3f          	test   $0x3f,%sil
  32:	74 0b                	je     0x3f
  34:	4c 89 f7             	mov    %r14,%rdi
  37:	5b                   	pop    %rbx
  38:	41 5e                	pop    %r14
  3a:	e9 71 c0 5e f7       	jmp    0xf75ec0b0
  3f:	48                   	rex.W