FAULT_INJECTION: forcing a failure.
name fail_usercopy, interval 1, probability 0, space 0, times 0
======================================================
WARNING: possible circular locking dependency detected
6.15.0-rc1-next-20250411-syzkaller #0 Not tainted
------------------------------------------------------
syz.4.121/6447 is trying to acquire lock:
ffffffff8ec1ac40 (console_owner){-...}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:336 [inline]
ffffffff8ec1ac40 (console_owner){-...}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:346 [inline]
ffffffff8ec1ac40 (console_owner){-...}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:288 [inline]
ffffffff8ec1ac40 (console_owner){-...}-{0:0}, at: console_flush_all+0x1a5/0xec0 kernel/printk/printk.c:3203

but task is already holding lock:
ffff8880b8739f18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:605

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&rq->__lock){-.-.}-{2:2}:
       lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
       _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378
       raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:605
       raw_spin_rq_lock kernel/sched/sched.h:1532 [inline]
       task_rq_lock+0xcb/0x440 kernel/sched/core.c:707
       cgroup_move_task+0x9b/0x660 kernel/sched/psi.c:1161
       css_set_move_task+0x72e/0x950 kernel/cgroup/cgroup.c:915
       cgroup_post_fork+0x27f/0x8c0 kernel/cgroup/cgroup.c:6723
       copy_process+0x39b5/0x3d10 kernel/fork.c:2675
       kernel_clone+0x242/0x930 kernel/fork.c:2861
       user_mode_thread+0x148/0x1c0 kernel/fork.c:2939
       rest_init+0x23/0x300 init/main.c:708
       start_kernel+0x484/0x510 init/main.c:1099
       x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:513
       x86_64_start_kernel+0x66/0x70 arch/x86/kernel/head64.c:494
       common_startup_64+0x13e/0x147

-> #3 (&p->pi_lock){-.-.}-{2:2}:
       lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd8/0x130 kernel/locking/spinlock.c:162
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:557 [inline]
       try_to_wake_up+0xc6/0x15d0 kernel/sched/core.c:4212
       __wake_up_common kernel/sched/wait.c:89 [inline]
       __wake_up_common_lock+0x130/0x1e0 kernel/sched/wait.c:106
       tty_port_default_wakeup+0xa6/0xf0 drivers/tty/tty_port.c:69
       serial8250_tx_chars+0x6e2/0x930 drivers/tty/serial/8250/8250_port.c:1842
       serial8250_handle_irq+0x631/0xb80 drivers/tty/serial/8250/8250_port.c:1950
       serial8250_default_handle_irq+0xd1/0x1f0 drivers/tty/serial/8250/8250_port.c:1970
       serial8250_interrupt+0xa9/0x1f0 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x29c/0xa60 kernel/irq/handle.c:158
       handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
       handle_irq_event+0x89/0x1f0 kernel/irq/handle.c:210
       handle_edge_irq+0x25f/0xc20 kernel/irq/chip.c:831
       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+0x136/0x230 arch/x86/kernel/irq.c:292
       common_interrupt+0xb4/0xd0 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+0x13/0x20 arch/x86/kernel/paravirt.c:80
       arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
       default_idle+0x13/0x20 arch/x86/kernel/process.c:748
       default_idle_call+0x74/0xb0 kernel/sched/idle.c:117
       cpuidle_idle_call kernel/sched/idle.c:185 [inline]
       do_idle+0x22e/0x5d0 kernel/sched/idle.c:325
       cpu_startup_entry+0x42/0x60 kernel/sched/idle.c:423
       rest_init+0x2dc/0x300 init/main.c:743
       start_kernel+0x484/0x510 init/main.c:1099
       x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:513
       x86_64_start_kernel+0x66/0x70 arch/x86/kernel/head64.c:494
       common_startup_64+0x13e/0x147

-> #2 (&tty->write_wait){-.-.}-{3:3}:
       lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd8/0x130 kernel/locking/spinlock.c:162
       __wake_up_common_lock+0x25/0x1e0 kernel/sched/wait.c:105
       tty_port_default_wakeup+0xa6/0xf0 drivers/tty/tty_port.c:69
       serial8250_tx_chars+0x6e2/0x930 drivers/tty/serial/8250/8250_port.c:1842
       serial8250_handle_irq+0x631/0xb80 drivers/tty/serial/8250/8250_port.c:1950
       serial8250_default_handle_irq+0xd1/0x1f0 drivers/tty/serial/8250/8250_port.c:1970
       serial8250_interrupt+0xa9/0x1f0 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x29c/0xa60 kernel/irq/handle.c:158
       handle_irq_event_percpu kernel/irq/handle.c:193 [inline]
       handle_irq_event+0x89/0x1f0 kernel/irq/handle.c:210
       handle_edge_irq+0x25f/0xc20 kernel/irq/chip.c:831
       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+0x136/0x230 arch/x86/kernel/irq.c:292
       common_interrupt+0xb4/0xd0 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+0x13/0x20 arch/x86/kernel/paravirt.c:80
       arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
       default_idle+0x13/0x20 arch/x86/kernel/process.c:748
       default_idle_call+0x74/0xb0 kernel/sched/idle.c:117
       cpuidle_idle_call kernel/sched/idle.c:185 [inline]
       do_idle+0x22e/0x5d0 kernel/sched/idle.c:325
       cpu_startup_entry+0x42/0x60 kernel/sched/idle.c:423
       rest_init+0x2dc/0x300 init/main.c:743
       start_kernel+0x484/0x510 init/main.c:1099
       x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:513
       x86_64_start_kernel+0x66/0x70 arch/x86/kernel/head64.c:494
       common_startup_64+0x13e/0x147

-> #1 (&port_lock_key){-.-.}-{3:3}:
       lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd8/0x130 kernel/locking/spinlock.c:162
       uart_port_lock_irqsave include/linux/serial_core.h:715 [inline]
       serial8250_console_write+0x1b0/0x1e00 drivers/tty/serial/8250/8250_port.c:3415
       console_emit_next_record kernel/printk/printk.c:3138 [inline]
       console_flush_all+0x86d/0xec0 kernel/printk/printk.c:3226
       __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
       console_unlock+0x151/0x3b0 kernel/printk/printk.c:3325
       vprintk_emit+0x761/0xa40 kernel/printk/printk.c:2450
       _printk+0xd5/0x120 kernel/printk/printk.c:2475
       register_console+0xc7b/0x1080 kernel/printk/printk.c:4125
       univ8250_console_init+0x52/0x90 drivers/tty/serial/8250/8250_core.c:513
       console_init+0x1b8/0x6f0 kernel/printk/printk.c:4323
       start_kernel+0x2dd/0x510 init/main.c:1034
       x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:513
       x86_64_start_kernel+0x66/0x70 arch/x86/kernel/head64.c:494
       common_startup_64+0x13e/0x147

-> #0 (console_owner){-...}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3166 [inline]
       check_prevs_add kernel/locking/lockdep.c:3285 [inline]
       validate_chain+0xa69/0x24e0 kernel/locking/lockdep.c:3909
       __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235
       lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
       console_lock_spinning_enable kernel/printk/printk.c:1924 [inline]
       console_emit_next_record kernel/printk/printk.c:3132 [inline]
       console_flush_all+0x7fa/0xec0 kernel/printk/printk.c:3226
       __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
       console_unlock+0x151/0x3b0 kernel/printk/printk.c:3325
       vprintk_emit+0x761/0xa40 kernel/printk/printk.c:2450
       _printk+0xd5/0x120 kernel/printk/printk.c:2475
       fail_dump lib/fault-inject.c:66 [inline]
       should_fail_ex+0x405/0x570 lib/fault-inject.c:174
       strncpy_from_user+0x36/0x280 lib/strncpy_from_user.c:118
       strncpy_from_user_nofault+0x71/0x140 mm/maccess.c:193
       bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:215 [inline]
       ____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:310 [inline]
       bpf_probe_read_compat_str+0xe9/0x180 kernel/trace/bpf_trace.c:306
       bpf_prog_c1796171ffc7efef+0x3e/0x40
       bpf_dispatcher_nop_func include/linux/bpf.h:1316 [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:2363 [inline]
       bpf_trace_run4+0x336/0x5a0 kernel/trace/bpf_trace.c:2406
       __bpf_trace_sched_switch+0x296/0x3d0 include/trace/events/sched.h:220
       __traceiter_sched_switch+0x98/0xd0 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+0x2920/0x5250 kernel/sched/core.c:6766
       preempt_schedule_irq+0xfe/0x1c0 kernel/sched/core.c:7092
       irqentry_exit+0x5e/0x90 kernel/entry/common.c:354
       asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:707
       kasan_check_range+0x1ba/0x2a0 mm/kasan/generic.c:189
       instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
       atomic_long_try_cmpxchg_release include/linux/atomic/atomic-instrumented.h:4480 [inline]
       __mutex_unlock_slowpath+0x229/0x800 kernel/locking/mutex.c:924
       fdput_pos include/linux/file.h:79 [inline]
       class_fd_pos_destructor include/linux/file.h:85 [inline]
       ksys_write+0x24e/0x2d0 fs/read_write.c:742
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xf3/0x230 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.4.121/6447:
 #0: ffff8880b8739f18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:605
 #1: ffffffff8ed3f180 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #1: ffffffff8ed3f180 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #1: ffffffff8ed3f180 (rcu_read_lock){....}-{1:3}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2362 [inline]
 #1: ffffffff8ed3f180 (rcu_read_lock){....}-{1:3}, at: bpf_trace_run4+0x246/0x5a0 kernel/trace/bpf_trace.c:2406
 #2: ffffffff8ec1aca0 (console_lock){+.+.}-{0:0}, at: _printk+0xd5/0x120 kernel/printk/printk.c:2475
 #3: ffffffff8ec1a8b0 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:336 [inline]
 #3: ffffffff8ec1a8b0 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:346 [inline]
 #3: ffffffff8ec1a8b0 (console_srcu){....}-{0:0}, at: console_srcu_read_lock kernel/printk/printk.c:288 [inline]
 #3: ffffffff8ec1a8b0 (console_srcu){....}-{0:0}, at: console_flush_all+0x1a5/0xec0 kernel/printk/printk.c:3203

stack backtrace:
CPU: 1 UID: 0 PID: 6447 Comm: syz.4.121 Not tainted 6.15.0-rc1-next-20250411-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2079
 check_noncircular+0x142/0x160 kernel/locking/lockdep.c:2211
 check_prev_add kernel/locking/lockdep.c:3166 [inline]
 check_prevs_add kernel/locking/lockdep.c:3285 [inline]
 validate_chain+0xa69/0x24e0 kernel/locking/lockdep.c:3909
 __lock_acquire+0xad5/0xd80 kernel/locking/lockdep.c:5235
 lock_acquire+0x116/0x2f0 kernel/locking/lockdep.c:5866
 console_lock_spinning_enable kernel/printk/printk.c:1924 [inline]
 console_emit_next_record kernel/printk/printk.c:3132 [inline]
 console_flush_all+0x7fa/0xec0 kernel/printk/printk.c:3226
 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
 console_unlock+0x151/0x3b0 kernel/printk/printk.c:3325
 vprintk_emit+0x761/0xa40 kernel/printk/printk.c:2450
 _printk+0xd5/0x120 kernel/printk/printk.c:2475
 fail_dump lib/fault-inject.c:66 [inline]
 should_fail_ex+0x405/0x570 lib/fault-inject.c:174
 strncpy_from_user+0x36/0x280 lib/strncpy_from_user.c:118
 strncpy_from_user_nofault+0x71/0x140 mm/maccess.c:193
 bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:215 [inline]
 ____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:310 [inline]
 bpf_probe_read_compat_str+0xe9/0x180 kernel/trace/bpf_trace.c:306
 bpf_prog_c1796171ffc7efef+0x3e/0x40
 bpf_dispatcher_nop_func include/linux/bpf.h:1316 [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:2363 [inline]
 bpf_trace_run4+0x336/0x5a0 kernel/trace/bpf_trace.c:2406
 __bpf_trace_sched_switch+0x296/0x3d0 include/trace/events/sched.h:220
 __traceiter_sched_switch+0x98/0xd0 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+0x2920/0x5250 kernel/sched/core.c:6766
 preempt_schedule_irq+0xfe/0x1c0 kernel/sched/core.c:7092
 irqentry_exit+0x5e/0x90 kernel/entry/common.c:354
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:707
RIP: 0010:kasan_check_range+0x1ba/0x2a0 mm/kasan/generic.c:189
Code: fb 48 8d 5d 07 48 85 ed 48 0f 49 dd 48 83 e3 f8 48 29 dd 74 12 41 80 3b 00 0f 85 b3 00 00 00 49 ff c3 48 ff cd 75 ee 5b 41 5c <41> 5e 41 5f 5d c3 cc cc cc cc 40 84 ed 75 61 f7 c5 00 ff 00 00 75
RSP: 0018:ffffc9001a067ce0 EFLAGS: 00000256
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff8c349229
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffc9001a067dc0
RBP: 0000000000000000 R08: ffffc9001a067dc7 R09: 1ffff9200340cfb8
R10: dffffc0000000000 R11: fffff5200340cfb9 R12: dffffc0000000000
R13: 1ffff9200340cfb8 R14: dffffc0000000001 R15: fffff5200340cfb9
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 atomic_long_try_cmpxchg_release include/linux/atomic/atomic-instrumented.h:4480 [inline]
 __mutex_unlock_slowpath+0x229/0x800 kernel/locking/mutex.c:924
 fdput_pos include/linux/file.h:79 [inline]
 class_fd_pos_destructor include/linux/file.h:85 [inline]
 ksys_write+0x24e/0x2d0 fs/read_write.c:742
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f971738cc1f
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:00007f9718248030 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000009 RCX: 00007f971738cc1f
RDX: 0000000000000001 RSI: 00007f9718248090 RDI: 0000000000000009
RBP: 00007f9718248090 R08: 0000000000000000 R09: 00007f9718247df7
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000002
R13: 0000000000000000 R14: 00007f97175b6160 R15: 00007ffd2960df68
 </TASK>
CPU: 1 UID: 0 PID: 6447 Comm: syz.4.121 Not tainted 6.15.0-rc1-next-20250411-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 fail_dump lib/fault-inject.c:73 [inline]
 should_fail_ex+0x424/0x570 lib/fault-inject.c:174
 strncpy_from_user+0x36/0x280 lib/strncpy_from_user.c:118
 strncpy_from_user_nofault+0x71/0x140 mm/maccess.c:193
 bpf_probe_read_user_str_common kernel/trace/bpf_trace.c:215 [inline]
 ____bpf_probe_read_compat_str kernel/trace/bpf_trace.c:310 [inline]
 bpf_probe_read_compat_str+0xe9/0x180 kernel/trace/bpf_trace.c:306
 bpf_prog_c1796171ffc7efef+0x3e/0x40
 bpf_dispatcher_nop_func include/linux/bpf.h:1316 [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:2363 [inline]
 bpf_trace_run4+0x336/0x5a0 kernel/trace/bpf_trace.c:2406
 __bpf_trace_sched_switch+0x296/0x3d0 include/trace/events/sched.h:220
 __traceiter_sched_switch+0x98/0xd0 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+0x2920/0x5250 kernel/sched/core.c:6766
 preempt_schedule_irq+0xfe/0x1c0 kernel/sched/core.c:7092
 irqentry_exit+0x5e/0x90 kernel/entry/common.c:354
 asm_sysvec_reschedule_ipi+0x1a/0x20 arch/x86/include/asm/idtentry.h:707
RIP: 0010:kasan_check_range+0x1ba/0x2a0 mm/kasan/generic.c:189
Code: fb 48 8d 5d 07 48 85 ed 48 0f 49 dd 48 83 e3 f8 48 29 dd 74 12 41 80 3b 00 0f 85 b3 00 00 00 49 ff c3 48 ff cd 75 ee 5b 41 5c <41> 5e 41 5f 5d c3 cc cc cc cc 40 84 ed 75 61 f7 c5 00 ff 00 00 75
RSP: 0018:ffffc9001a067ce0 EFLAGS: 00000256
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff8c349229
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffffc9001a067dc0
RBP: 0000000000000000 R08: ffffc9001a067dc7 R09: 1ffff9200340cfb8
R10: dffffc0000000000 R11: fffff5200340cfb9 R12: dffffc0000000000
R13: 1ffff9200340cfb8 R14: dffffc0000000001 R15: fffff5200340cfb9
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 atomic_long_try_cmpxchg_release include/linux/atomic/atomic-instrumented.h:4480 [inline]
 __mutex_unlock_slowpath+0x229/0x800 kernel/locking/mutex.c:924
 fdput_pos include/linux/file.h:79 [inline]
 class_fd_pos_destructor include/linux/file.h:85 [inline]
 ksys_write+0x24e/0x2d0 fs/read_write.c:742
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f971738cc1f
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:00007f9718248030 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000009 RCX: 00007f971738cc1f
RDX: 0000000000000001 RSI: 00007f9718248090 RDI: 0000000000000009
RBP: 00007f9718248090 R08: 0000000000000000 R09: 00007f9718247df7
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000002
R13: 0000000000000000 R14: 00007f97175b6160 R15: 00007ffd2960df68
 </TASK>
----------------
Code disassembly (best guess):
   0:	fb                   	sti
   1:	48 8d 5d 07          	lea    0x7(%rbp),%rbx
   5:	48 85 ed             	test   %rbp,%rbp
   8:	48 0f 49 dd          	cmovns %rbp,%rbx
   c:	48 83 e3 f8          	and    $0xfffffffffffffff8,%rbx
  10:	48 29 dd             	sub    %rbx,%rbp
  13:	74 12                	je     0x27
  15:	41 80 3b 00          	cmpb   $0x0,(%r11)
  19:	0f 85 b3 00 00 00    	jne    0xd2
  1f:	49 ff c3             	inc    %r11
  22:	48 ff cd             	dec    %rbp
  25:	75 ee                	jne    0x15
  27:	5b                   	pop    %rbx
  28:	41 5c                	pop    %r12
* 2a:	41 5e                	pop    %r14 <-- trapping instruction
  2c:	41 5f                	pop    %r15
  2e:	5d                   	pop    %rbp
  2f:	c3                   	ret
  30:	cc                   	int3
  31:	cc                   	int3
  32:	cc                   	int3
  33:	cc                   	int3
  34:	40 84 ed             	test   %bpl,%bpl
  37:	75 61                	jne    0x9a
  39:	f7 c5 00 ff 00 00    	test   $0xff00,%ebp
  3f:	75                   	.byte 0x75