FAULT_INJECTION: forcing a failure.
name fail_usercopy, interval 1, probability 0, space 0, times 0
======================================================
WARNING: possible circular locking dependency detected
6.14.0-rc6-syzkaller-00103-g4003c9e78778 #0 Not tainted
------------------------------------------------------
syz.0.1821/12948 is trying to acquire lock:
ffffffff8ea15038 ((console_sem).lock){-.-.}-{2:2}, at: down_trylock+0x20/0xa0 kernel/locking/semaphore.c:139

but task is already holding lock:
ffff8880b863e958 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xb0/0x140 kernel/sched/core.c:606

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (&rq->__lock){-.-.}-{2:2}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378
       raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:598
       raw_spin_rq_lock kernel/sched/sched.h:1521 [inline]
       task_rq_lock+0xc6/0x360 kernel/sched/core.c:700
       cgroup_move_task+0x9b/0x5a0 kernel/sched/psi.c:1161
       css_set_move_task+0x72e/0x950 kernel/cgroup/cgroup.c:898
       cgroup_post_fork+0x284/0x8b0 kernel/cgroup/cgroup.c:6695
       copy_process+0x398a/0x3cf0 kernel/fork.c:2629
       kernel_clone+0x226/0x8e0 kernel/fork.c:2815
       user_mode_thread+0x144/0x1c0 kernel/fork.c:2893
       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:515
       x86_64_start_kernel+0x66/0x70 arch/x86/kernel/head64.c:496
       common_startup_64+0x13e/0x147

-> #1 (&p->pi_lock){-.-.}-{2:2}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:551 [inline]
       try_to_wake_up+0xc2/0x1470 kernel/sched/core.c:4214
       up+0x72/0x90 kernel/locking/semaphore.c:191
       __up_console_sem kernel/printk/printk.c:343 [inline]
       __console_unlock+0x123/0x1f0 kernel/printk/printk.c:2869
       __console_flush_and_unlock kernel/printk/printk.c:3271 [inline]
       console_unlock+0x18f/0x3b0 kernel/printk/printk.c:3309
       do_con_write+0x4b29/0x4c20 drivers/tty/vt/vt.c:3105
       con_write+0x26/0x40 drivers/tty/vt/vt.c:3432
       process_output_block drivers/tty/n_tty.c:574 [inline]
       n_tty_write+0xd64/0x1230 drivers/tty/n_tty.c:2389
       iterate_tty_write drivers/tty/tty_io.c:1015 [inline]
       file_tty_write+0x548/0x9b0 drivers/tty/tty_io.c:1090
       new_sync_write fs/read_write.c:586 [inline]
       vfs_write+0xad1/0xd10 fs/read_write.c:679
       ksys_write+0x18f/0x2b0 fs/read_write.c:731
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 ((console_sem).lock){-.-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3163 [inline]
       check_prevs_add kernel/locking/lockdep.c:3282 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
       __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
       down_trylock+0x20/0xa0 kernel/locking/semaphore.c:139
       __down_trylock_console_sem+0x109/0x250 kernel/printk/printk.c:326
       console_trylock kernel/printk/printk.c:2852 [inline]
       console_trylock_spinning kernel/printk/printk.c:2009 [inline]
       vprintk_emit+0x3d7/0xa10 kernel/printk/printk.c:2431
       _printk+0xd5/0x120 kernel/printk/printk.c:2457
       fail_dump lib/fault-inject.c:66 [inline]
       should_fail_ex+0x3eb/0x550 lib/fault-inject.c:174
       strncpy_from_user+0x36/0x270 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:1290 [inline]
       __bpf_prog_run include/linux/filter.h:701 [inline]
       bpf_prog_run include/linux/filter.h:708 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2371 [inline]
       bpf_trace_run4+0x336/0x590 kernel/trace/bpf_trace.c:2414
       __bpf_trace_sched_switch+0x294/0x3d0 include/trace/events/sched.h:222
       __traceiter_sched_switch+0x9a/0xd0 include/trace/events/sched.h:222
       __do_trace_sched_switch include/trace/events/sched.h:222 [inline]
       trace_sched_switch include/trace/events/sched.h:222 [inline]
       __schedule+0x23ad/0x4c90 kernel/sched/core.c:6762
       preempt_schedule_common+0x84/0xd0 kernel/sched/core.c:6944
       preempt_schedule+0xe1/0xf0 kernel/sched/core.c:6968
       preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk.S:12
       class_preempt_destructor include/linux/preempt.h:480 [inline]
       file_ref_put include/linux/file_ref.h:161 [inline]
       fput+0x20d/0x290 fs/file_table.c:516
       fdput include/linux/file.h:63 [inline]
       fdput_pos include/linux/file.h:80 [inline]
       class_fd_pos_destructor include/linux/file.h:85 [inline]
       ksys_write+0x251/0x2b0 fs/read_write.c:737
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  (console_sem).lock --> &p->pi_lock --> &rq->__lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&rq->__lock);
                               lock(&p->pi_lock);
                               lock(&rq->__lock);
  lock((console_sem).lock);

 *** DEADLOCK ***

2 locks held by syz.0.1821/12948:
 #0: ffff8880b863e958 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xb0/0x140 kernel/sched/core.c:606
 #1: ffffffff8eb393e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #1: ffffffff8eb393e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffffff8eb393e0 (rcu_read_lock){....}-{1:3}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2370 [inline]
 #1: ffffffff8eb393e0 (rcu_read_lock){....}-{1:3}, at: bpf_trace_run4+0x244/0x590 kernel/trace/bpf_trace.c:2414

stack backtrace:
CPU: 1 UID: 0 PID: 12948 Comm: syz.0.1821 Not tainted 6.14.0-rc6-syzkaller-00103-g4003c9e78778 #0
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+0x13a/0x1b0 kernel/locking/lockdep.c:2076
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2208
 check_prev_add kernel/locking/lockdep.c:3163 [inline]
 check_prevs_add kernel/locking/lockdep.c:3282 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
 down_trylock+0x20/0xa0 kernel/locking/semaphore.c:139
 __down_trylock_console_sem+0x109/0x250 kernel/printk/printk.c:326
 console_trylock kernel/printk/printk.c:2852 [inline]
 console_trylock_spinning kernel/printk/printk.c:2009 [inline]
 vprintk_emit+0x3d7/0xa10 kernel/printk/printk.c:2431
 _printk+0xd5/0x120 kernel/printk/printk.c:2457
 fail_dump lib/fault-inject.c:66 [inline]
 should_fail_ex+0x3eb/0x550 lib/fault-inject.c:174
 strncpy_from_user+0x36/0x270 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:1290 [inline]
 __bpf_prog_run include/linux/filter.h:701 [inline]
 bpf_prog_run include/linux/filter.h:708 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2371 [inline]
 bpf_trace_run4+0x336/0x590 kernel/trace/bpf_trace.c:2414
 __bpf_trace_sched_switch+0x294/0x3d0 include/trace/events/sched.h:222
 __traceiter_sched_switch+0x9a/0xd0 include/trace/events/sched.h:222
 __do_trace_sched_switch include/trace/events/sched.h:222 [inline]
 trace_sched_switch include/trace/events/sched.h:222 [inline]
 __schedule+0x23ad/0x4c90 kernel/sched/core.c:6762
 preempt_schedule_common+0x84/0xd0 kernel/sched/core.c:6944
 preempt_schedule+0xe1/0xf0 kernel/sched/core.c:6968
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk.S:12
 class_preempt_destructor include/linux/preempt.h:480 [inline]
 file_ref_put include/linux/file_ref.h:161 [inline]
 fput+0x20d/0x290 fs/file_table.c:516
 fdput include/linux/file.h:63 [inline]
 fdput_pos include/linux/file.h:80 [inline]
 class_fd_pos_destructor include/linux/file.h:85 [inline]
 ksys_write+0x251/0x2b0 fs/read_write.c:737
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8ca838bc1f
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:00007f8ca9204030 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000000000a RCX: 00007f8ca838bc1f
RDX: 0000000000000001 RSI: 00007f8ca9204090 RDI: 000000000000000a
RBP: 00007f8ca9204090 R08: 0000000000000000 R09: 00007f8ca9203df7
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f8ca85a6160 R15: 00007ffe25400078
 </TASK>
CPU: 1 UID: 0 PID: 12948 Comm: syz.0.1821 Not tainted 6.14.0-rc6-syzkaller-00103-g4003c9e78778 #0
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+0x40a/0x550 lib/fault-inject.c:174
 strncpy_from_user+0x36/0x270 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:1290 [inline]
 __bpf_prog_run include/linux/filter.h:701 [inline]
 bpf_prog_run include/linux/filter.h:708 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2371 [inline]
 bpf_trace_run4+0x336/0x590 kernel/trace/bpf_trace.c:2414
 __bpf_trace_sched_switch+0x294/0x3d0 include/trace/events/sched.h:222
 __traceiter_sched_switch+0x9a/0xd0 include/trace/events/sched.h:222
 __do_trace_sched_switch include/trace/events/sched.h:222 [inline]
 trace_sched_switch include/trace/events/sched.h:222 [inline]
 __schedule+0x23ad/0x4c90 kernel/sched/core.c:6762
 preempt_schedule_common+0x84/0xd0 kernel/sched/core.c:6944
 preempt_schedule+0xe1/0xf0 kernel/sched/core.c:6968
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk.S:12
 class_preempt_destructor include/linux/preempt.h:480 [inline]
 file_ref_put include/linux/file_ref.h:161 [inline]
 fput+0x20d/0x290 fs/file_table.c:516
 fdput include/linux/file.h:63 [inline]
 fdput_pos include/linux/file.h:80 [inline]
 class_fd_pos_destructor include/linux/file.h:85 [inline]
 ksys_write+0x251/0x2b0 fs/read_write.c:737
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8ca838bc1f
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:00007f8ca9204030 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000000000a RCX: 00007f8ca838bc1f
RDX: 0000000000000001 RSI: 00007f8ca9204090 RDI: 000000000000000a
RBP: 00007f8ca9204090 R08: 0000000000000000 R09: 00007f8ca9203df7
R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f8ca85a6160 R15: 00007ffe25400078
 </TASK>
loop0: detected capacity change from 0 to 32768