FAULT_INJECTION: forcing a failure.
name fail_usercopy, interval 1, probability 0, space 0, times 1
======================================================
WARNING: possible circular locking dependency detected
6.15.0-rc2-syzkaller-00042-g1a1d569a75f3 #0 Not tainted
------------------------------------------------------
syz.1.156/6510 is trying to acquire lock:
ffffffff8ec19ac0 (console_owner){-...}-{0:0}, at: console_trylock_spinning kernel/printk/printk.c:2048 [inline]
ffffffff8ec19ac0 (console_owner){-...}-{0:0}, at: vprintk_emit+0x552/0xa40 kernel/printk/printk.c:2449

but task is already holding lock:
ffff8880b8639b18 (&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:1513 [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:911
       cgroup_post_fork+0x27f/0x8c0 kernel/cgroup/cgroup.c:6715
       copy_process+0x39b5/0x3d10 kernel/fork.c:2658
       kernel_clone+0x242/0x930 kernel/fork.c:2844
       user_mode_thread+0x148/0x1c0 kernel/fork.c:2922
       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
       __pollwake fs/select.c:205 [inline]
       pollwake+0x1da/0x290 fs/select.c:215
       __wake_up_common kernel/sched/wait.c:89 [inline]
       __wake_up_common_lock+0x132/0x1e0 kernel/sched/wait.c:106
       tty_ldisc_lock+0x60/0xc0 drivers/tty/tty_ldisc.c:311
       tty_set_ldisc+0x5f/0x560 drivers/tty/tty_ldisc.c:529
       tty_ioctl+0xbd4/0xdc0 drivers/tty/tty_io.c:2738
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl+0xf3/0x160 fs/ioctl.c:892
       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

-> #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+0xab/0x1f0 drivers/tty/serial/8250/8250_core.c:86
       __handle_irq_event_percpu+0x29e/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+0x138/0x230 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
       __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
       _raw_spin_unlock_irqrestore+0xd9/0x140 kernel/locking/spinlock.c:194
       spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
       uart_port_unlock_irqrestore include/linux/serial_core.h:786 [inline]
       uart_write+0x3e4/0xa40 drivers/tty/serial/serial_core.c:636
       process_output_block drivers/tty/n_tty.c:561 [inline]
       n_tty_write+0xd83/0x1270 drivers/tty/n_tty.c:2377
       iterate_tty_write drivers/tty/tty_io.c:1015 [inline]
       file_tty_write+0x545/0x9d0 drivers/tty/tty_io.c:1090
       new_sync_write fs/read_write.c:591 [inline]
       vfs_write+0x711/0xd10 fs/read_write.c:684
       ksys_write+0x19d/0x2d0 fs/read_write.c:736
       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

-> #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_trylock_spinning kernel/printk/printk.c:2048 [inline]
       vprintk_emit+0x56f/0xa40 kernel/printk/printk.c:2449
       _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/0x44
       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+0x338/0x5a0 kernel/trace/bpf_trace.c:2406
       __bpf_trace_sched_switch+0x296/0x3d0 include/trace/events/sched.h:220
       __traceiter_sched_switch+0x9a/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+0x2910/0x5240 kernel/sched/core.c:6764
       __schedule_loop kernel/sched/core.c:6845 [inline]
       schedule+0x163/0x360 kernel/sched/core.c:6860
       schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6917
       __mutex_lock_common kernel/locking/mutex.c:678 [inline]
       __mutex_lock+0x805/0x10c0 kernel/locking/mutex.c:746
       rtnl_lock net/core/rtnetlink.c:80 [inline]
       rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
       rtnl_newlink+0xd68/0x1fe0 net/core/rtnetlink.c:4067
       rtnetlink_rcv_msg+0x811/0xd70 net/core/rtnetlink.c:6958
       netlink_rcv_skb+0x20a/0x480 net/netlink/af_netlink.c:2534
       netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
       netlink_unicast+0x7fa/0x9a0 net/netlink/af_netlink.c:1339
       netlink_sendmsg+0x8c3/0xcd0 net/netlink/af_netlink.c:1883
       sock_sendmsg_nosec net/socket.c:712 [inline]
       __sock_sendmsg+0x223/0x270 net/socket.c:727
       ____sys_sendmsg+0x523/0x860 net/socket.c:2566
       ___sys_sendmsg net/socket.c:2620 [inline]
       __sys_sendmsg+0x271/0x360 net/socket.c:2652
       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 ***

3 locks held by syz.1.156/6510:
 #0: ffffffff900fd588 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline]
 #0: ffffffff900fd588 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 #0: ffffffff900fd588 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0xd68/0x1fe0 net/core/rtnetlink.c:4067
 #1: ffff8880b8639b18 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:605
 #2: ffffffff8ed3dfa0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8ed3dfa0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8ed3dfa0 (rcu_read_lock){....}-{1:3}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2362 [inline]
 #2: ffffffff8ed3dfa0 (rcu_read_lock){....}-{1:3}, at: bpf_trace_run4+0x246/0x5a0 kernel/trace/bpf_trace.c:2406

stack backtrace:
CPU: 0 UID: 0 PID: 6510 Comm: syz.1.156 Not tainted 6.15.0-rc2-syzkaller-00042-g1a1d569a75f3 #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_trylock_spinning kernel/printk/printk.c:2048 [inline]
 vprintk_emit+0x56f/0xa40 kernel/printk/printk.c:2449
 _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/0x44
 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+0x338/0x5a0 kernel/trace/bpf_trace.c:2406
 __bpf_trace_sched_switch+0x296/0x3d0 include/trace/events/sched.h:220
 __traceiter_sched_switch+0x9a/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+0x2910/0x5240 kernel/sched/core.c:6764
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0x163/0x360 kernel/sched/core.c:6860
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6917
 __mutex_lock_common kernel/locking/mutex.c:678 [inline]
 __mutex_lock+0x805/0x10c0 kernel/locking/mutex.c:746
 rtnl_lock net/core/rtnetlink.c:80 [inline]
 rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 rtnl_newlink+0xd68/0x1fe0 net/core/rtnetlink.c:4067
 rtnetlink_rcv_msg+0x811/0xd70 net/core/rtnetlink.c:6958
 netlink_rcv_skb+0x20a/0x480 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x7fa/0x9a0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8c3/0xcd0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x223/0x270 net/socket.c:727
 ____sys_sendmsg+0x523/0x860 net/socket.c:2566
 ___sys_sendmsg net/socket.c:2620 [inline]
 __sys_sendmsg+0x271/0x360 net/socket.c:2652
 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: 0033:0x7f961358e169
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:00007f961443f038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f96137b5fa0 RCX: 00007f961358e169
RDX: 0000000024040800 RSI: 0000200000000000 RDI: 0000000000000005
RBP: 00007f961443f090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f96137b5fa0 R15: 00007fff0485a638
 </TASK>
CPU: 0 UID: 0 PID: 6510 Comm: syz.1.156 Not tainted 6.15.0-rc2-syzkaller-00042-g1a1d569a75f3 #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/0x44
 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+0x338/0x5a0 kernel/trace/bpf_trace.c:2406
 __bpf_trace_sched_switch+0x296/0x3d0 include/trace/events/sched.h:220
 __traceiter_sched_switch+0x9a/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+0x2910/0x5240 kernel/sched/core.c:6764
 __schedule_loop kernel/sched/core.c:6845 [inline]
 schedule+0x163/0x360 kernel/sched/core.c:6860
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6917
 __mutex_lock_common kernel/locking/mutex.c:678 [inline]
 __mutex_lock+0x805/0x10c0 kernel/locking/mutex.c:746
 rtnl_lock net/core/rtnetlink.c:80 [inline]
 rtnl_nets_lock net/core/rtnetlink.c:341 [inline]
 rtnl_newlink+0xd68/0x1fe0 net/core/rtnetlink.c:4067
 rtnetlink_rcv_msg+0x811/0xd70 net/core/rtnetlink.c:6958
 netlink_rcv_skb+0x20a/0x480 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x7fa/0x9a0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8c3/0xcd0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x223/0x270 net/socket.c:727
 ____sys_sendmsg+0x523/0x860 net/socket.c:2566
 ___sys_sendmsg net/socket.c:2620 [inline]
 __sys_sendmsg+0x271/0x360 net/socket.c:2652
 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: 0033:0x7f961358e169
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:00007f961443f038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f96137b5fa0 RCX: 00007f961358e169
RDX: 0000000024040800 RSI: 0000200000000000 RDI: 0000000000000005
RBP: 00007f961443f090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f96137b5fa0 R15: 00007fff0485a638
 </TASK>