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.5.330/7157 is trying to acquire lock:
ffffffff8df31660 (console_owner){-.-.}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:336 [inline]
ffffffff8df31660 (console_owner){-.-.}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:335 [inline]
ffffffff8df31660 (console_owner){-.-.}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:289 [inline]
ffffffff8df31660 (console_owner){-.-.}-{0:0}, at: console_flush_all+0x13a/0xb10 kernel/printk/printk.c:3176

but task is already holding lock:
ffff8880b883a058 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:646

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&rq->__lock){-.-.}-{2:2}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       _raw_spin_lock_nested+0x32/0x50 kernel/locking/spinlock.c:378
       raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:638
       raw_spin_rq_lock kernel/sched/sched.h:1547 [inline]
       task_rq_lock+0xbc/0x470 kernel/sched/core.c:738
       cgroup_move_task+0x92/0x2a0 kernel/sched/psi.c:1170
       css_set_move_task+0x658/0x9e0 kernel/cgroup/cgroup.c:951
       cgroup_post_fork+0x1ef/0x790 kernel/cgroup/cgroup.c:6913
       copy_process+0x3862/0x3c00 kernel/fork.c:2425
       kernel_clone+0x21e/0x840 kernel/fork.c:2609
       user_mode_thread+0xdd/0x140 kernel/fork.c:2685
       rest_init+0x23/0x300 init/main.c:722
       start_kernel+0x3ae/0x410 init/main.c:1111
       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291
       common_startup_64+0x13e/0x147

-> #3 (&p->pi_lock){-.-.}-{2:2}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:557 [inline]
       try_to_wake_up+0x67/0x12b0 kernel/sched/core.c:4181
       create_worker+0x503/0x720 kernel/workqueue.c:2834
       workqueue_init+0x3f0/0x6a0 kernel/workqueue.c:7944
       kernel_init_freeable+0x302/0x4b0 init/main.c:1578
       kernel_init+0x1d/0x1d0 init/main.c:1483
       ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

-> #2 (&pool->lock){-.-.}-{2:2}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       __queue_work+0x809/0xfb0 kernel/workqueue.c:-1
       queue_work_on+0x181/0x270 kernel/workqueue.c:2392
       serial8250_modem_status+0x1ac/0x2a0 drivers/tty/serial/8250/8250_port.c:1747
       serial8250_handle_irq+0x576/0xbb0 drivers/tty/serial/8250/8250_port.c:1824
       serial8250_default_handle_irq+0xbf/0x200 drivers/tty/serial/8250/8250_port.c:1846
       serial8250_interrupt+0x8d/0x180 drivers/tty/serial/8250/8250_core.c:82
       __handle_irq_event_percpu+0x295/0xab0 kernel/irq/handle.c:203
       handle_irq_event_percpu kernel/irq/handle.c:240 [inline]
       handle_irq_event+0x8b/0x1e0 kernel/irq/handle.c:257
       handle_edge_irq+0x23b/0xa10 kernel/irq/chip.c:855
       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:-1 [inline]
       __common_interrupt+0x141/0x1f0 arch/x86/kernel/irq.c:325
       common_interrupt+0xb6/0xe0 arch/x86/kernel/irq.c:318
       asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:688
       variable_test_bit arch/x86/include/asm/bitops.h:222 [inline]
       arch_test_bit arch/x86/include/asm/bitops.h:233 [inline]
       _test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
       cpumask_test_cpu include/linux/cpumask.h:646 [inline]
       cpu_online include/linux/cpumask.h:1205 [inline]
       trace_contention_begin+0x32/0x120 include/trace/events/lock.h:95
       __mutex_lock_common kernel/locking/mutex.c:600 [inline]
       __mutex_lock+0x198/0x1350 kernel/locking/mutex.c:760
       __unix_dgram_recvmsg+0x1e1/0xd60 net/unix/af_unix.c:2598
       sock_recvmsg_nosec+0x186/0x1c0 net/socket.c:1078
       ____sys_recvmsg+0x3aa/0x460 net/socket.c:2848
       ___sys_recvmsg+0x1b5/0x510 net/socket.c:2892
       do_recvmmsg+0x307/0x770 net/socket.c:2987
       __sys_recvmmsg net/socket.c:3061 [inline]
       __do_sys_recvmmsg net/socket.c:3084 [inline]
       __se_sys_recvmmsg net/socket.c:3077 [inline]
       __x64_sys_recvmmsg+0x190/0x240 net/socket.c:3077
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&port_lock_key){-.-.}-{3:3}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xa7/0xf0 kernel/locking/spinlock.c:162
       uart_port_lock_irqsave include/linux/serial_core.h:717 [inline]
       serial8250_console_write+0x17e/0x1ba0 drivers/tty/serial/8250/8250_port.c:3301
       console_emit_next_record kernel/printk/printk.c:3111 [inline]
       console_flush_all+0x6f3/0xb10 kernel/printk/printk.c:3199
       __console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
       console_unlock+0xbb/0x190 kernel/printk/printk.c:3298
       vprintk_emit+0x4c5/0x590 kernel/printk/printk.c:2423
       _printk+0xcf/0x120 kernel/printk/printk.c:2448
       register_console+0xa8b/0xf90 kernel/printk/printk.c:4099
       univ8250_console_init+0x3a/0x70 drivers/tty/serial/8250/8250_core.c:511
       console_init+0x10e/0x430 kernel/printk/printk.c:4298
       start_kernel+0x254/0x410 init/main.c:1048
       x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
       x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291
       common_startup_64+0x13e/0x147

-> #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+0xb9b/0x2140 kernel/locking/lockdep.c:3908
       __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       console_lock_spinning_enable kernel/printk/printk.c:1897 [inline]
       console_emit_next_record kernel/printk/printk.c:3105 [inline]
       console_flush_all+0x69c/0xb10 kernel/printk/printk.c:3199
       __console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
       console_unlock+0xbb/0x190 kernel/printk/printk.c:3298
       vprintk_emit+0x4c5/0x590 kernel/printk/printk.c:2423
       _printk+0xcf/0x120 kernel/printk/printk.c:2448
       fail_dump lib/fault-inject.c:66 [inline]
       should_fail_ex+0x3f5/0x560 lib/fault-inject.c:174
       strncpy_from_user+0x36/0x290 lib/strncpy_from_user.c:118
       strncpy_from_user_nofault+0x72/0x150 mm/maccess.c:192
       bpf_trace_copy_string kernel/bpf/helpers.c:758 [inline]
       bpf_bprintf_prepare+0xb91/0x13a0 kernel/bpf/helpers.c:976
       ____bpf_trace_printk kernel/trace/bpf_trace.c:372 [inline]
       bpf_trace_printk+0xdb/0x190 kernel/trace/bpf_trace.c:362
       bpf_prog_930ede9872f2967c+0x3e/0x44
       bpf_dispatcher_nop_func include/linux/bpf.h:1350 [inline]
       __bpf_prog_run include/linux/filter.h:721 [inline]
       bpf_prog_run include/linux/filter.h:728 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2075 [inline]
       bpf_trace_run2+0x284/0x4b0 kernel/trace/bpf_trace.c:2116
       __bpf_trace_contention_begin+0xdc/0x130 include/trace/events/lock.h:95
       __do_trace_contention_begin include/trace/events/lock.h:95 [inline]
       trace_contention_begin+0x114/0x140 include/trace/events/lock.h:95
       __pv_queued_spin_lock_slowpath+0xf0/0xb60 kernel/locking/qspinlock.c:219
       pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:557 [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+0x21f/0x290 kernel/locking/spinlock_debug.c:116
       raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:646
       raw_spin_rq_lock kernel/sched/sched.h:1547 [inline]
       rq_lock kernel/sched/sched.h:1869 [inline]
       __schedule+0x36b/0x4cc0 kernel/sched/core.c:6833
       __schedule_loop kernel/sched/core.c:7011 [inline]
       schedule+0x165/0x360 kernel/sched/core.c:7026
       exit_to_user_mode_loop+0x4c/0x130 kernel/entry/common.c:31
       exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
       syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
       syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
       do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
       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.5.330/7157:
 #0: ffff8880b883a058 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:646
 #1: ffffffff8df3d6e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #1: ffffffff8df3d6e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #1: ffffffff8df3d6e0 (rcu_read_lock){....}-{1:3}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2074 [inline]
 #1: ffffffff8df3d6e0 (rcu_read_lock){....}-{1:3}, at: bpf_trace_run2+0x186/0x4b0 kernel/trace/bpf_trace.c:2116
 #2: ffffffff8df316c0 (console_lock){+.+.}-{0:0}, at: _printk+0xcf/0x120 kernel/printk/printk.c:2448
 #3: ffffffff8de18f90 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:336 [inline]
 #3: ffffffff8de18f90 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:335 [inline]
 #3: ffffffff8de18f90 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:289 [inline]
 #3: ffffffff8de18f90 (console_srcu){....}-{0:0}, at: console_flush_all+0x13a/0xb10 kernel/printk/printk.c:3176

stack backtrace:
CPU: 0 UID: 0 PID: 7157 Comm: syz.5.330 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
 check_noncircular+0x134/0x160 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+0xb9b/0x2140 kernel/locking/lockdep.c:3908
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 console_lock_spinning_enable kernel/printk/printk.c:1897 [inline]
 console_emit_next_record kernel/printk/printk.c:3105 [inline]
 console_flush_all+0x69c/0xb10 kernel/printk/printk.c:3199
 __console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
 console_unlock+0xbb/0x190 kernel/printk/printk.c:3298
 vprintk_emit+0x4c5/0x590 kernel/printk/printk.c:2423
 _printk+0xcf/0x120 kernel/printk/printk.c:2448
 fail_dump lib/fault-inject.c:66 [inline]
 should_fail_ex+0x3f5/0x560 lib/fault-inject.c:174
 strncpy_from_user+0x36/0x290 lib/strncpy_from_user.c:118
 strncpy_from_user_nofault+0x72/0x150 mm/maccess.c:192
 bpf_trace_copy_string kernel/bpf/helpers.c:758 [inline]
 bpf_bprintf_prepare+0xb91/0x13a0 kernel/bpf/helpers.c:976
 ____bpf_trace_printk kernel/trace/bpf_trace.c:372 [inline]
 bpf_trace_printk+0xdb/0x190 kernel/trace/bpf_trace.c:362
 bpf_prog_930ede9872f2967c+0x3e/0x44
 bpf_dispatcher_nop_func include/linux/bpf.h:1350 [inline]
 __bpf_prog_run include/linux/filter.h:721 [inline]
 bpf_prog_run include/linux/filter.h:728 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2075 [inline]
 bpf_trace_run2+0x284/0x4b0 kernel/trace/bpf_trace.c:2116
 __bpf_trace_contention_begin+0xdc/0x130 include/trace/events/lock.h:95
 __do_trace_contention_begin include/trace/events/lock.h:95 [inline]
 trace_contention_begin+0x114/0x140 include/trace/events/lock.h:95
 __pv_queued_spin_lock_slowpath+0xf0/0xb60 kernel/locking/qspinlock.c:219
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:557 [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+0x21f/0x290 kernel/locking/spinlock_debug.c:116
 raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:646
 raw_spin_rq_lock kernel/sched/sched.h:1547 [inline]
 rq_lock kernel/sched/sched.h:1869 [inline]
 __schedule+0x36b/0x4cc0 kernel/sched/core.c:6833
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026
 exit_to_user_mode_loop+0x4c/0x130 kernel/entry/common.c:31
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5b9ef8e17f
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:00007f5b9fdd9030 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: 0000000000000001 RBX: 0000000000000006 RCX: 00007f5b9ef8e17f
RDX: 0000000000000001 RSI: 00007f5b9fdd9090 RDI: 0000000000000006
RBP: 00007f5b9fdd9090 R08: 0000000000000000 R09: 00007f5b9fdd8df7
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 00007f5b9f1e6038 R14: 00007f5b9f1e5fa0 R15: 00007ffe0ea20018
 </TASK>
CPU: 0 UID: 0 PID: 7157 Comm: syz.5.330 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 fail_dump lib/fault-inject.c:73 [inline]
 should_fail_ex+0x414/0x560 lib/fault-inject.c:174
 strncpy_from_user+0x36/0x290 lib/strncpy_from_user.c:118
 strncpy_from_user_nofault+0x72/0x150 mm/maccess.c:192
 bpf_trace_copy_string kernel/bpf/helpers.c:758 [inline]
 bpf_bprintf_prepare+0xb91/0x13a0 kernel/bpf/helpers.c:976
 ____bpf_trace_printk kernel/trace/bpf_trace.c:372 [inline]
 bpf_trace_printk+0xdb/0x190 kernel/trace/bpf_trace.c:362
 bpf_prog_930ede9872f2967c+0x3e/0x44
 bpf_dispatcher_nop_func include/linux/bpf.h:1350 [inline]
 __bpf_prog_run include/linux/filter.h:721 [inline]
 bpf_prog_run include/linux/filter.h:728 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2075 [inline]
 bpf_trace_run2+0x284/0x4b0 kernel/trace/bpf_trace.c:2116
 __bpf_trace_contention_begin+0xdc/0x130 include/trace/events/lock.h:95
 __do_trace_contention_begin include/trace/events/lock.h:95 [inline]
 trace_contention_begin+0x114/0x140 include/trace/events/lock.h:95
 __pv_queued_spin_lock_slowpath+0xf0/0xb60 kernel/locking/qspinlock.c:219
 pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:557 [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+0x21f/0x290 kernel/locking/spinlock_debug.c:116
 raw_spin_rq_lock_nested+0xad/0x140 kernel/sched/core.c:646
 raw_spin_rq_lock kernel/sched/sched.h:1547 [inline]
 rq_lock kernel/sched/sched.h:1869 [inline]
 __schedule+0x36b/0x4cc0 kernel/sched/core.c:6833
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026
 exit_to_user_mode_loop+0x4c/0x130 kernel/entry/common.c:31
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5b9ef8e17f
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:00007f5b9fdd9030 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: 0000000000000001 RBX: 0000000000000006 RCX: 00007f5b9ef8e17f
RDX: 0000000000000001 RSI: 00007f5b9fdd9090 RDI: 0000000000000006
RBP: 00007f5b9fdd9090 R08: 0000000000000000 R09: 00007f5b9fdd8df7
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 00007f5b9f1e6038 R14: 00007f5b9f1e5fa0 R15: 00007ffe0ea20018
 </TASK>