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.3.215/7215 is trying to acquire lock:
ffffffff8cd24160 (console_owner){-...}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:339 [inline]
ffffffff8cd24160 (console_owner){-...}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:232 [inline]
ffffffff8cd24160 (console_owner){-...}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:292 [inline]
ffffffff8cd24160 (console_owner){-...}-{0:0}, at: console_flush_all+0x10f/0xd00 kernel/printk/printk.c:2992

but task is already holding lock:
ffff8880b8e3c018 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:566

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:378
       raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:558
       raw_spin_rq_lock kernel/sched/sched.h:1372 [inline]
       rq_lock kernel/sched/sched.h:1681 [inline]
       task_fork_fair+0x62/0x1f0 kernel/sched/fair.c:12688
       sched_cgroup_fork+0x333/0x3c0 kernel/sched/core.c:4816
       copy_process+0x21e4/0x3d70 kernel/fork.c:2614
       kernel_clone+0x21b/0x840 kernel/fork.c:2914
       user_mode_thread+0xde/0x130 kernel/fork.c:2992
       rest_init+0x27/0x300 init/main.c:709
       arch_call_rest_init+0xe/0x10 init/main.c:841
       start_kernel+0x459/0x4e0 init/main.c:1086
       x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555
       copy_bootdata+0x0/0xe0 arch/x86/kernel/head64.c:536
       secondary_startup_64_no_verify+0x179/0x17b

-> #3 (&p->pi_lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa8/0xf0 kernel/locking/spinlock.c:162
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:522 [inline]
       try_to_wake_up+0x60/0x1140 kernel/sched/core.c:4232
       __wake_up_common+0x2a4/0x4e0 kernel/sched/wait.c:107
       __wake_up_common_lock kernel/sched/wait.c:138 [inline]
       __wake_up+0x112/0x190 kernel/sched/wait.c:160
       tty_port_default_wakeup+0xa2/0xf0 drivers/tty/tty_port.c:69
       serial8250_tx_chars+0x6bd/0x8a0 drivers/tty/serial/8250/8250_port.c:1837
       serial8250_handle_irq+0x534/0x6e0 drivers/tty/serial/8250/8250_port.c:1944
       serial8250_default_handle_irq+0xb8/0x1a0 drivers/tty/serial/8250/8250_port.c:1964
       serial8250_interrupt+0x9f/0x1c0 drivers/tty/serial/8250/8250_core.c:127
       __handle_irq_event_percpu+0x276/0x930 kernel/irq/handle.c:158
       handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
       handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:210
       handle_edge_irq+0x247/0xb30 kernel/irq/chip.c:831
       generic_handle_irq_desc include/linux/irqdesc.h:161 [inline]
       handle_irq arch/x86/kernel/irq.c:240 [inline]
       __common_interrupt+0x13b/0x230 arch/x86/kernel/irq.c:259
       common_interrupt+0xb4/0xd0 arch/x86/kernel/irq.c:249
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:678
       lock_acquire+0xa/0x410 kernel/locking/lockdep.c:5722
       down_read+0x46/0x2e0 kernel/locking/rwsem.c:1520
       anon_vma_lock_read include/linux/rmap.h:131 [inline]
       validate_mm+0x1a8/0x420 mm/mmap.c:316
       do_vmi_align_munmap+0x148a/0x1660 mm/mmap.c:2597
       do_vmi_munmap+0x252/0x2d0 mm/mmap.c:2660
       __mmap_region mm/mmap.c:2710 [inline]
       mmap_region+0x741/0x2020 mm/mmap.c:2941
       do_mmap+0x92f/0x10a0 mm/mmap.c:1385
       vm_mmap_pgoff+0x1c0/0x400 mm/util.c:556
       ksys_mmap_pgoff+0x520/0x700 mm/mmap.c:1431
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 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+0xa8/0xf0 kernel/locking/spinlock.c:162
       __wake_up_common_lock kernel/sched/wait.c:137 [inline]
       __wake_up+0xf8/0x190 kernel/sched/wait.c:160
       tty_port_default_wakeup+0xa2/0xf0 drivers/tty/tty_port.c:69
       serial8250_tx_chars+0x6bd/0x8a0 drivers/tty/serial/8250/8250_port.c:1837
       serial8250_handle_irq+0x534/0x6e0 drivers/tty/serial/8250/8250_port.c:1944
       serial8250_default_handle_irq+0xb8/0x1a0 drivers/tty/serial/8250/8250_port.c:1964
       serial8250_interrupt+0x9f/0x1c0 drivers/tty/serial/8250/8250_core.c:127
       __handle_irq_event_percpu+0x276/0x930 kernel/irq/handle.c:158
       handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
       handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:210
       handle_edge_irq+0x247/0xb30 kernel/irq/chip.c:831
       generic_handle_irq_desc include/linux/irqdesc.h:161 [inline]
       handle_irq arch/x86/kernel/irq.c:240 [inline]
       __common_interrupt+0x13b/0x230 arch/x86/kernel/irq.c:259
       common_interrupt+0xb4/0xd0 arch/x86/kernel/irq.c:249
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:678
       __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
       _raw_spin_unlock_irqrestore+0xa9/0x110 kernel/locking/spinlock.c:194
       spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
       uart_write+0x45b/0x5d0 drivers/tty/serial/serial_core.c:634
       process_output_block drivers/tty/n_tty.c:580 [inline]
       n_tty_write+0xd27/0x11d0 drivers/tty/n_tty.c:2395
       iterate_tty_write drivers/tty/tty_io.c:1017 [inline]
       file_tty_write+0x54b/0x980 drivers/tty/tty_io.c:1088
       call_write_iter include/linux/fs.h:2018 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x43b/0x940 fs/read_write.c:584
       ksys_write+0x147/0x250 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 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+0xa8/0xf0 kernel/locking/spinlock.c:162
       serial8250_console_write+0x16d/0x17a0 drivers/tty/serial/8250/8250_port.c:3433
       console_emit_next_record kernel/printk/printk.c:2944 [inline]
       console_flush_all+0x6cd/0xd00 kernel/printk/printk.c:3000
       console_unlock+0xae/0x340 kernel/printk/printk.c:3069
       vprintk_emit+0x477/0x600 kernel/printk/printk.c:2341
       _printk+0xd0/0x110 kernel/printk/printk.c:2366
       register_console+0x91b/0xe60 kernel/printk/printk.c:3583
       univ8250_console_init+0x45/0x50 drivers/tty/serial/8250/8250_core.c:717
       console_init+0x17b/0x5e0 kernel/printk/printk.c:3726
       start_kernel+0x2c0/0x4e0 init/main.c:1022
       x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:555
       copy_bootdata+0x0/0xe0 arch/x86/kernel/head64.c:536
       secondary_startup_64_no_verify+0x179/0x17b

-> #0 (console_owner){-...}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
       lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
       console_lock_spinning_enable kernel/printk/printk.c:1871 [inline]
       console_emit_next_record kernel/printk/printk.c:2938 [inline]
       console_flush_all+0x693/0xd00 kernel/printk/printk.c:3000
       console_unlock+0xae/0x340 kernel/printk/printk.c:3069
       vprintk_emit+0x477/0x600 kernel/printk/printk.c:2341
       _printk+0xd0/0x110 kernel/printk/printk.c:2366
       fail_dump lib/fault-inject.c:45 [inline]
       should_fail_ex+0x37e/0x4d0 lib/fault-inject.c:153
       strncpy_from_user+0x36/0x2e0 lib/strncpy_from_user.c:118
       strncpy_from_user_nofault+0x71/0x140 mm/maccess.c:186
       bpf_trace_copy_string kernel/bpf/helpers.c:755 [inline]
       bpf_bprintf_prepare+0xb9b/0x1400 kernel/bpf/helpers.c:980
       ____bpf_trace_printk kernel/trace/bpf_trace.c:381 [inline]
       bpf_trace_printk+0xdc/0x190 kernel/trace/bpf_trace.c:371
       bpf_prog_7c77c7e0f6645ad8+0x3d/0x3f
       bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline]
       __bpf_prog_run include/linux/filter.h:612 [inline]
       bpf_prog_run include/linux/filter.h:619 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline]
       bpf_trace_run2+0x1d1/0x3c0 kernel/trace/bpf_trace.c:2361
       __bpf_trace_contention_begin+0xdd/0x130 include/trace/events/lock.h:95
       trace_contention_begin+0xe9/0x110 include/trace/events/lock.h:95
       __pv_queued_spin_lock_slowpath+0xe0/0x9d0 kernel/locking/qspinlock.c:405
       pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:586 [inline]
       queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
       queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
       do_raw_spin_lock+0x24e/0x2c0 kernel/locking/spinlock_debug.c:115
       raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:566
       raw_spin_rq_lock kernel/sched/sched.h:1372 [inline]
       rq_lock kernel/sched/sched.h:1681 [inline]
       __schedule+0x2dd/0x44d0 kernel/sched/core.c:6613
       schedule+0xbd/0x170 kernel/sched/core.c:6773
       exit_to_user_mode_loop+0x47/0x110 kernel/entry/common.c:165
       exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
       __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
       syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
       do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
       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 ***

4 locks held by syz.3.215/7215:
 #0: ffff8880b8e3c018 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:566
 #1: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline]
 #1: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline]
 #1: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2321 [inline]
 #1: ffffffff8cd2ff20 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0xde/0x3c0 kernel/trace/bpf_trace.c:2361
 #2: ffffffff8cd24240 (console_lock){+.+.}-{0:0}, at: _printk+0xd0/0x110 kernel/printk/printk.c:2366
 #3: ffffffff8cc0ba50 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:339 [inline]
 #3: ffffffff8cc0ba50 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:232 [inline]
 #3: ffffffff8cc0ba50 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:292 [inline]
 #3: ffffffff8cc0ba50 (console_srcu){....}-{0:0}, at: console_flush_all+0x10f/0xd00 kernel/printk/printk.c:2992

stack backtrace:
CPU: 1 PID: 7215 Comm: syz.3.215 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_noncircular+0x2bd/0x3c0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 console_lock_spinning_enable kernel/printk/printk.c:1871 [inline]
 console_emit_next_record kernel/printk/printk.c:2938 [inline]
 console_flush_all+0x693/0xd00 kernel/printk/printk.c:3000
 console_unlock+0xae/0x340 kernel/printk/printk.c:3069
 vprintk_emit+0x477/0x600 kernel/printk/printk.c:2341
 _printk+0xd0/0x110 kernel/printk/printk.c:2366
 fail_dump lib/fault-inject.c:45 [inline]
 should_fail_ex+0x37e/0x4d0 lib/fault-inject.c:153
 strncpy_from_user+0x36/0x2e0 lib/strncpy_from_user.c:118
 strncpy_from_user_nofault+0x71/0x140 mm/maccess.c:186
 bpf_trace_copy_string kernel/bpf/helpers.c:755 [inline]
 bpf_bprintf_prepare+0xb9b/0x1400 kernel/bpf/helpers.c:980
 ____bpf_trace_printk kernel/trace/bpf_trace.c:381 [inline]
 bpf_trace_printk+0xdc/0x190 kernel/trace/bpf_trace.c:371
 bpf_prog_7c77c7e0f6645ad8+0x3d/0x3f
 bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline]
 __bpf_prog_run include/linux/filter.h:612 [inline]
 bpf_prog_run include/linux/filter.h:619 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline]
 bpf_trace_run2+0x1d1/0x3c0 kernel/trace/bpf_trace.c:2361
 __bpf_trace_contention_begin+0xdd/0x130 include/trace/events/lock.h:95
 trace_contention_begin+0xe9/0x110 include/trace/events/lock.h:95
 __pv_queued_spin_lock_slowpath+0xe0/0x9d0 kernel/locking/qspinlock.c:405
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:586 [inline]
 queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x24e/0x2c0 kernel/locking/spinlock_debug.c:115
 raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:566
 raw_spin_rq_lock kernel/sched/sched.h:1372 [inline]
 rq_lock kernel/sched/sched.h:1681 [inline]
 __schedule+0x2dd/0x44d0 kernel/sched/core.c:6613
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 exit_to_user_mode_loop+0x47/0x110 kernel/entry/common.c:165
 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f2e5f38e1ff
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:00007f2e5d5f6030 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: 0000000000000001 RBX: 000000000000000f RCX: 00007f2e5f38e1ff
RDX: 0000000000000001 RSI: 00007f2e5d5f6090 RDI: 000000000000000f
RBP: 00007f2e5d5f6090 R08: 0000000000000000 R09: 00007f2e5d5f5df7
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 00007f2e5f5e6218 R14: 00007f2e5f5e6180 R15: 00007ffe25015bf8
 </TASK>
CPU: 1 PID: 7215 Comm: syz.3.215 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail_ex+0x39d/0x4d0 lib/fault-inject.c:153
 strncpy_from_user+0x36/0x2e0 lib/strncpy_from_user.c:118
 strncpy_from_user_nofault+0x71/0x140 mm/maccess.c:186
 bpf_trace_copy_string kernel/bpf/helpers.c:755 [inline]
 bpf_bprintf_prepare+0xb9b/0x1400 kernel/bpf/helpers.c:980
 ____bpf_trace_printk kernel/trace/bpf_trace.c:381 [inline]
 bpf_trace_printk+0xdc/0x190 kernel/trace/bpf_trace.c:371
 bpf_prog_7c77c7e0f6645ad8+0x3d/0x3f
 bpf_dispatcher_nop_func include/linux/bpf.h:1224 [inline]
 __bpf_prog_run include/linux/filter.h:612 [inline]
 bpf_prog_run include/linux/filter.h:619 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2322 [inline]
 bpf_trace_run2+0x1d1/0x3c0 kernel/trace/bpf_trace.c:2361
 __bpf_trace_contention_begin+0xdd/0x130 include/trace/events/lock.h:95
 trace_contention_begin+0xe9/0x110 include/trace/events/lock.h:95
 __pv_queued_spin_lock_slowpath+0xe0/0x9d0 kernel/locking/qspinlock.c:405
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:586 [inline]
 queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
 queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
 do_raw_spin_lock+0x24e/0x2c0 kernel/locking/spinlock_debug.c:115
 raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:566
 raw_spin_rq_lock kernel/sched/sched.h:1372 [inline]
 rq_lock kernel/sched/sched.h:1681 [inline]
 __schedule+0x2dd/0x44d0 kernel/sched/core.c:6613
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 exit_to_user_mode_loop+0x47/0x110 kernel/entry/common.c:165
 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
 do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f2e5f38e1ff
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:00007f2e5d5f6030 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: 0000000000000001 RBX: 000000000000000f RCX: 00007f2e5f38e1ff
RDX: 0000000000000001 RSI: 00007f2e5d5f6090 RDI: 000000000000000f
RBP: 00007f2e5d5f6090 R08: 0000000000000000 R09: 00007f2e5d5f5df7
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 00007f2e5f5e6218 R14: 00007f2e5f5e6180 R15: 00007ffe25015bf8
 </TASK>