FAULT_INJECTION: forcing a failure.
name fail_usercopy, interval 1, probability 0, space 0, times 0
======================================================
WARNING: possible circular locking dependency detected
6.16.0-rc3-syzkaller #0 Not tainted
------------------------------------------------------
syz.3.6947/1278 is trying to acquire lock:
ffffffff8e4d1ee0 (console_owner){-.-.}-{0:0}, at: console_lock_spinning_enable+0x9f/0xd0 kernel/printk/printk.c:1924

but task is already holding lock:
ffff8880b843a2d8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:614 [inline]
ffff8880b843a2d8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x7e/0x130 kernel/sched/core.c:599

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+0x31/0x40 kernel/locking/spinlock.c:378
       raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:606
       raw_spin_rq_lock kernel/sched/sched.h:1532 [inline]
       task_rq_lock+0xcf/0x490 kernel/sched/core.c:708
       cgroup_move_task+0x81/0x2a0 kernel/sched/psi.c:1161
       css_set_move_task+0x288/0x5f0 kernel/cgroup/cgroup.c:918
       cgroup_post_fork+0x201/0x9e0 kernel/cgroup/cgroup.c:6754
       copy_process+0x5cfc/0x76a0 kernel/fork.c:2413
       kernel_clone+0xfc/0x960 kernel/fork.c:2599
       user_mode_thread+0xc7/0x110 kernel/fork.c:2677
       rest_init+0x23/0x2b0 init/main.c:710
       start_kernel+0x3ee/0x4d0 init/main.c:1102
       x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:307
       x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:288
       common_startup_64+0x13e/0x148

-> #3 (&p->pi_lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:557 [inline]
       try_to_wake_up+0xb2/0x1680 kernel/sched/core.c:4226
       __wake_up_common+0x135/0x1f0 kernel/sched/wait.c:89
       __wake_up_common_lock kernel/sched/wait.c:106 [inline]
       __wake_up+0x31/0x60 kernel/sched/wait.c:127
       tty_port_default_wakeup+0x2a/0x40 drivers/tty/tty_port.c:69
       serial8250_tx_chars+0x68e/0x860 drivers/tty/serial/8250/8250_port.c:1838
       serial8250_handle_irq+0x761/0xcb0 drivers/tty/serial/8250/8250_port.c:1946
       serial8250_default_handle_irq+0x9a/0x210 drivers/tty/serial/8250/8250_port.c:1966
       serial8250_interrupt+0x103/0x210 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x229/0x7d0 kernel/irq/handle.c:158
       handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
       handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210
       handle_edge_irq+0x28e/0xab0 kernel/irq/chip.c:797
       generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
       handle_irq arch/x86/kernel/irq.c:254 [inline]
       call_irq_handler arch/x86/kernel/irq.c:266 [inline]
       __common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:292
       common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:285
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
       native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
       pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:81
       arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
       default_idle+0x13/0x20 arch/x86/kernel/process.c:749
       default_idle_call+0x6d/0xb0 kernel/sched/idle.c:117
       cpuidle_idle_call kernel/sched/idle.c:185 [inline]
       do_idle+0x391/0x510 kernel/sched/idle.c:325
       cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423
       start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:315
       common_startup_64+0x13e/0x148

-> #2 (&tty->write_wait){-.-.}-{3:3}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
       __wake_up_common_lock kernel/sched/wait.c:105 [inline]
       __wake_up+0x1c/0x60 kernel/sched/wait.c:127
       tty_port_default_wakeup+0x2a/0x40 drivers/tty/tty_port.c:69
       serial8250_tx_chars+0x68e/0x860 drivers/tty/serial/8250/8250_port.c:1838
       serial8250_handle_irq+0x761/0xcb0 drivers/tty/serial/8250/8250_port.c:1946
       serial8250_default_handle_irq+0x9a/0x210 drivers/tty/serial/8250/8250_port.c:1966
       serial8250_interrupt+0x103/0x210 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x229/0x7d0 kernel/irq/handle.c:158
       handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
       handle_irq_event+0xab/0x1e0 kernel/irq/handle.c:210
       handle_edge_irq+0x28e/0xab0 kernel/irq/chip.c:797
       generic_handle_irq_desc include/linux/irqdesc.h:173 [inline]
       handle_irq arch/x86/kernel/irq.c:254 [inline]
       call_irq_handler arch/x86/kernel/irq.c:266 [inline]
       __common_interrupt+0xdf/0x250 arch/x86/kernel/irq.c:292
       common_interrupt+0xba/0xe0 arch/x86/kernel/irq.c:285
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:693
       native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
       pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:81
       arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
       default_idle+0x13/0x20 arch/x86/kernel/process.c:749
       default_idle_call+0x6d/0xb0 kernel/sched/idle.c:117
       cpuidle_idle_call kernel/sched/idle.c:185 [inline]
       do_idle+0x391/0x510 kernel/sched/idle.c:325
       cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423
       start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:315
       common_startup_64+0x13e/0x148

-> #1 (&port_lock_key){-.-.}-{3:3}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
       uart_port_lock_irqsave include/linux/serial_core.h:717 [inline]
       serial8250_console_write+0x181/0x1890 drivers/tty/serial/8250/8250_port.c:3415
       console_emit_next_record kernel/printk/printk.c:3138 [inline]
       console_flush_all+0x801/0xc60 kernel/printk/printk.c:3226
       __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
       console_unlock+0xd8/0x210 kernel/printk/printk.c:3325
       vprintk_emit+0x418/0x6d0 kernel/printk/printk.c:2450
       _printk+0xc7/0x100 kernel/printk/printk.c:2475
       register_console+0xc2d/0x11b0 kernel/printk/printk.c:4125
       univ8250_console_init+0x5f/0x90 drivers/tty/serial/8250/8250_core.c:513
       console_init+0x14f/0x680 kernel/printk/printk.c:4323
       start_kernel+0x29f/0x4d0 init/main.c:1036
       x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:307
       x86_64_start_kernel+0x130/0x190 arch/x86/kernel/head64.c:288
       common_startup_64+0x13e/0x148

-> #0 (console_owner){-.-.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3168 [inline]
       check_prevs_add kernel/locking/lockdep.c:3287 [inline]
       validate_chain kernel/locking/lockdep.c:3911 [inline]
       __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5240
       lock_acquire kernel/locking/lockdep.c:5871 [inline]
       lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5828
       console_lock_spinning_enable+0xb0/0xd0 kernel/printk/printk.c:1924
       console_emit_next_record kernel/printk/printk.c:3132 [inline]
       console_flush_all+0x7aa/0xc60 kernel/printk/printk.c:3226
       __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
       console_unlock+0xd8/0x210 kernel/printk/printk.c:3325
       vprintk_emit+0x418/0x6d0 kernel/printk/printk.c:2450
       _printk+0xc7/0x100 kernel/printk/printk.c:2475
       fail_dump lib/fault-inject.c:66 [inline]
       should_fail_ex+0x4e7/0x640 lib/fault-inject.c:174
       strncpy_from_user+0x3b/0x2e0 lib/strncpy_from_user.c:118
       strncpy_from_user_nofault+0x7f/0x180 mm/maccess.c:193
       bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:215 [inline]
       ____bpf_probe_read_user_str kernel/trace/bpf_trace.c:224 [inline]
       bpf_probe_read_user_str+0x26/0x70 kernel/trace/bpf_trace.c:221
       bpf_prog_bc7c5c6b9645592f+0x3e/0x44
       bpf_dispatcher_nop_func include/linux/bpf.h:1322 [inline]
       __bpf_prog_run include/linux/filter.h:718 [inline]
       bpf_prog_run include/linux/filter.h:725 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2258 [inline]
       bpf_trace_run4+0x249/0x5a0 kernel/trace/bpf_trace.c:2301
       __bpf_trace_sched_switch+0x145/0x190 include/trace/events/sched.h:220
       __traceiter_sched_switch+0x6f/0xc0 include/trace/events/sched.h:220
       __do_trace_sched_switch include/trace/events/sched.h:220 [inline]
       trace_sched_switch include/trace/events/sched.h:220 [inline]
       __schedule+0x1bee/0x5de0 kernel/sched/core.c:6782
       __schedule_loop kernel/sched/core.c:6863 [inline]
       schedule+0xe7/0x3a0 kernel/sched/core.c:6878
       mISDN_read+0x47e/0x910 drivers/isdn/mISDN/timerdev.c:112
       vfs_read+0x1e4/0xc60 fs/read_write.c:570
       ksys_read+0x12a/0x250 fs/read_write.c:715
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xcd/0x4c0 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 ***

4 locks held by syz.3.6947/1278:
 #0: ffff8880b843a2d8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:614 [inline]
 #0: ffff8880b843a2d8 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x7e/0x130 kernel/sched/core.c:599
 #1: ffffffff8e5c4940 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #1: ffffffff8e5c4940 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #1: ffffffff8e5c4940 (rcu_read_lock){....}-{1:3}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2257 [inline]
 #1: ffffffff8e5c4940 (rcu_read_lock){....}-{1:3}, at: bpf_trace_run4+0x1cf/0x5a0 kernel/trace/bpf_trace.c:2301
 #2: ffffffff8e5b2320 (console_lock){+.+.}-{0:0}, at: _printk+0xc7/0x100 kernel/printk/printk.c:2475
 #3: ffffffff8e5b2390 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:336 [inline]
 #3: ffffffff8e5b2390 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:346 [inline]
 #3: ffffffff8e5b2390 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:288 [inline]
 #3: ffffffff8e5b2390 (console_srcu){....}-{0:0}, at: console_flush_all+0x158/0xc60 kernel/printk/printk.c:3203

stack backtrace:
CPU: 0 UID: 0 PID: 1278 Comm: syz.3.6947 Not tainted 6.16.0-rc3-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2046
 check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3168 [inline]
 check_prevs_add kernel/locking/lockdep.c:3287 [inline]
 validate_chain kernel/locking/lockdep.c:3911 [inline]
 __lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5240
 lock_acquire kernel/locking/lockdep.c:5871 [inline]
 lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5828
 console_lock_spinning_enable+0xb0/0xd0 kernel/printk/printk.c:1924
 console_emit_next_record kernel/printk/printk.c:3132 [inline]
 console_flush_all+0x7aa/0xc60 kernel/printk/printk.c:3226
 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
 console_unlock+0xd8/0x210 kernel/printk/printk.c:3325
 vprintk_emit+0x418/0x6d0 kernel/printk/printk.c:2450
 _printk+0xc7/0x100 kernel/printk/printk.c:2475
 fail_dump lib/fault-inject.c:66 [inline]
 should_fail_ex+0x4e7/0x640 lib/fault-inject.c:174
 strncpy_from_user+0x3b/0x2e0 lib/strncpy_from_user.c:118
 strncpy_from_user_nofault+0x7f/0x180 mm/maccess.c:193
 bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:215 [inline]
 ____bpf_probe_read_user_str kernel/trace/bpf_trace.c:224 [inline]
 bpf_probe_read_user_str+0x26/0x70 kernel/trace/bpf_trace.c:221
 bpf_prog_bc7c5c6b9645592f+0x3e/0x44
 bpf_dispatcher_nop_func include/linux/bpf.h:1322 [inline]
 __bpf_prog_run include/linux/filter.h:718 [inline]
 bpf_prog_run include/linux/filter.h:725 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2258 [inline]
 bpf_trace_run4+0x249/0x5a0 kernel/trace/bpf_trace.c:2301
 __bpf_trace_sched_switch+0x145/0x190 include/trace/events/sched.h:220
 __traceiter_sched_switch+0x6f/0xc0 include/trace/events/sched.h:220
 __do_trace_sched_switch include/trace/events/sched.h:220 [inline]
 trace_sched_switch include/trace/events/sched.h:220 [inline]
 __schedule+0x1bee/0x5de0 kernel/sched/core.c:6782
 __schedule_loop kernel/sched/core.c:6863 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6878
 mISDN_read+0x47e/0x910 drivers/isdn/mISDN/timerdev.c:112
 vfs_read+0x1e4/0xc60 fs/read_write.c:570
 ksys_read+0x12a/0x250 fs/read_write.c:715
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f345b58e929
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:00007f345c33b038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f345b7b5fa0 RCX: 00007f345b58e929
RDX: 0000000000001001 RSI: 00002000000019c0 RDI: 0000000000000006
RBP: 00007f345c33b090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f345b7b5fa0 R15: 00007fff12a20728
 </TASK>
CPU: 0 UID: 0 PID: 1278 Comm: syz.3.6947 Not tainted 6.16.0-rc3-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 fail_dump lib/fault-inject.c:73 [inline]
 should_fail_ex+0x512/0x640 lib/fault-inject.c:174
 strncpy_from_user+0x3b/0x2e0 lib/strncpy_from_user.c:118
 strncpy_from_user_nofault+0x7f/0x180 mm/maccess.c:193
 bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:215 [inline]
 ____bpf_probe_read_user_str kernel/trace/bpf_trace.c:224 [inline]
 bpf_probe_read_user_str+0x26/0x70 kernel/trace/bpf_trace.c:221
 bpf_prog_bc7c5c6b9645592f+0x3e/0x44
 bpf_dispatcher_nop_func include/linux/bpf.h:1322 [inline]
 __bpf_prog_run include/linux/filter.h:718 [inline]
 bpf_prog_run include/linux/filter.h:725 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2258 [inline]
 bpf_trace_run4+0x249/0x5a0 kernel/trace/bpf_trace.c:2301
 __bpf_trace_sched_switch+0x145/0x190 include/trace/events/sched.h:220
 __traceiter_sched_switch+0x6f/0xc0 include/trace/events/sched.h:220
 __do_trace_sched_switch include/trace/events/sched.h:220 [inline]
 trace_sched_switch include/trace/events/sched.h:220 [inline]
 __schedule+0x1bee/0x5de0 kernel/sched/core.c:6782
 __schedule_loop kernel/sched/core.c:6863 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6878
 mISDN_read+0x47e/0x910 drivers/isdn/mISDN/timerdev.c:112
 vfs_read+0x1e4/0xc60 fs/read_write.c:570
 ksys_read+0x12a/0x250 fs/read_write.c:715
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f345b58e929
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:00007f345c33b038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f345b7b5fa0 RCX: 00007f345b58e929
RDX: 0000000000001001 RSI: 00002000000019c0 RDI: 0000000000000006
RBP: 00007f345c33b090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f345b7b5fa0 R15: 00007fff12a20728
 </TASK>