syzbot

kauditd_printk_skb: 9 callbacks suppressed
audit: type=1800 audit(1731828236.598:84): pid=8906 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="syz.1.810" name="bus" dev="overlay" ino=1020 res=0 errno=0
audit: type=1800 audit(1731828236.698:85): pid=8913 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="syz.1.810" name="bus" dev="overlay" ino=1020 res=0 errno=0
======================================================
WARNING: possible circular locking dependency detected
6.12.0-rc7-syzkaller-00212-g4a5df3796467 #0 Not tainted
------------------------------------------------------
kauditd/29 is trying to acquire lock:
ffff88805b364618 (&p->pi_lock){-.-.}-{2:2}, at: class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:551 [inline]
ffff88805b364618 (&p->pi_lock){-.-.}-{2:2}, at: try_to_wake_up+0xbe/0x14b0 kernel/sched/core.c:4165

but task is already holding lock:
ffffffff8e813418 ((console_sem).lock){-.-.}-{2:2}, at: up+0x1d/0x90 kernel/locking/semaphore.c:187

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 ((console_sem).lock){-.-.}-{2:2}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
       __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:2827 [inline]
       console_trylock_spinning kernel/printk/printk.c:1990 [inline]
       vprintk_emit+0x3d7/0xa10 kernel/printk/printk.c:2406
       _printk+0xd5/0x120 kernel/printk/printk.c:2432
       fail_dump lib/fault-inject.c:46 [inline]
       should_fail_ex+0x391/0x4e0 lib/fault-inject.c:154
       strncpy_from_user+0x36/0x260 lib/strncpy_from_user.c:118
       strncpy_from_user_nofault+0x71/0x140 mm/maccess.c:186
       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
       0xffffffffa0000859
       bpf_dispatcher_nop_func include/linux/bpf.h:1265 [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:2316 [inline]
       bpf_trace_run2+0x2ec/0x540 kernel/trace/bpf_trace.c:2357
       trace_tlb_flush+0x118/0x140 include/trace/events/tlb.h:38
       switch_mm_irqs_off+0x77a/0xa70
       context_switch kernel/sched/core.c:5312 [inline]
       __schedule+0x10c7/0x4bd0 kernel/sched/core.c:6693
       preempt_schedule_notrace+0x100/0x140 kernel/sched/core.c:6965
       preempt_schedule_notrace_thunk+0x1a/0x30 arch/x86/entry/thunk.S:13
       rcu_is_watching+0x7e/0xb0 kernel/rcu/tree.c:738
       trace_lock_acquire include/trace/events/lock.h:24 [inline]
       lock_acquire+0xe3/0x550 kernel/locking/lockdep.c:5796
       rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
       rcu_read_lock include/linux/rcupdate.h:849 [inline]
       atomic_notifier_call_chain+0x43/0x180 kernel/notifier.c:230
       do_con_write+0xab1/0x4c30 drivers/tty/vt/vt.c:3086
       con_put_char+0x95/0xf0 drivers/tty/vt/vt.c:3442
       tty_put_char+0xe3/0x190 drivers/tty/tty_io.c:3167
       do_output_char+0x6b1/0x970 drivers/tty/n_tty.c:469
       process_output drivers/tty/n_tty.c:494 [inline]
       n_tty_write+0xe06/0x1230 drivers/tty/n_tty.c:2400
       iterate_tty_write drivers/tty/tty_io.c:1015 [inline]
       file_tty_write+0x546/0x9b0 drivers/tty/tty_io.c:1090
       new_sync_write fs/read_write.c:590 [inline]
       vfs_write+0xaeb/0xd30 fs/read_write.c:683
       ksys_write+0x183/0x2b0 fs/read_write.c:736
       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

-> #1 (&rq->__lock){-.-.}-{2:2}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
       _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:1506 [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+0x256/0x880 kernel/cgroup/cgroup.c:6692
       copy_process+0x39e9/0x3d50 kernel/fork.c:2600
       kernel_clone+0x223/0x880 kernel/fork.c:2786
       user_mode_thread+0x132/0x1a0 kernel/fork.c:2864
       rest_init+0x23/0x300 init/main.c:712
       start_kernel+0x47f/0x500 init/main.c:1105
       x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:507
       x86_64_start_kernel+0x9f/0xa0 arch/x86/kernel/head64.c:488
       common_startup_64+0x13e/0x147

-> #0 (&p->pi_lock){-.-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
       __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
       __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+0xbe/0x14b0 kernel/sched/core.c:4165
       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:2844
       __console_flush_and_unlock kernel/printk/printk.c:3241 [inline]
       console_unlock+0x18f/0x3b0 kernel/printk/printk.c:3279
       vprintk_emit+0x730/0xa10 kernel/printk/printk.c:2407
       _printk+0xd5/0x120 kernel/printk/printk.c:2432
       kauditd_printk_skb kernel/audit.c:546 [inline]
       kauditd_hold_skb+0x1be/0x210 kernel/audit.c:581
       kauditd_send_queue+0x2b1/0x310 kernel/audit.c:766
       kauditd_thread+0x74a/0x9b0 kernel/audit.c:890
       kthread+0x2f0/0x390 kernel/kthread.c:389
       ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

other info that might help us debug this:

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

 Possible unsafe locking scenario:

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

 *** DEADLOCK ***

1 lock held by kauditd/29:
 #0: ffffffff8e813418 ((console_sem).lock){-.-.}-{2:2}, at: up+0x1d/0x90 kernel/locking/semaphore.c:187

stack backtrace:
CPU: 1 UID: 0 PID: 29 Comm: kauditd Not tainted 6.12.0-rc7-syzkaller-00212-g4a5df3796467 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
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:2074
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
 __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+0xbe/0x14b0 kernel/sched/core.c:4165
 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:2844
 __console_flush_and_unlock kernel/printk/printk.c:3241 [inline]
 console_unlock+0x18f/0x3b0 kernel/printk/printk.c:3279
 vprintk_emit+0x730/0xa10 kernel/printk/printk.c:2407
 _printk+0xd5/0x120 kernel/printk/printk.c:2432
 kauditd_printk_skb kernel/audit.c:546 [inline]
 kauditd_hold_skb+0x1be/0x210 kernel/audit.c:581
 kauditd_send_queue+0x2b1/0x310 kernel/audit.c:766
 kauditd_thread+0x74a/0x9b0 kernel/audit.c:890
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>