[ OK ] Started Getty on tty2. [ OK ] Started Getty on tty1. [ OK ] Started Serial Getty on ttyS0. [ OK ] Reached target Login Prompts. [ OK ] Reached target Multi-User System. [ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... Starting Load/Save RF Kill Switch Status... [ OK ] Started Update UTMP about System Runlevel Changes. [ OK ] Started Load/Save RF Kill Switch Status. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.10.27' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 43.321764][ C0] [ 43.324249][ C0] ======================================================== [ 43.331735][ C0] WARNING: possible irq lock inversion dependency detected [ 43.339167][ C0] 5.6.0-syzkaller #0 Not tainted [ 43.344369][ C0] -------------------------------------------------------- [ 43.351542][ C0] swapper/0/0 just changed the state of lock: [ 43.357579][ C0] ffff8880a84d9cd8 (&ctx->ctx_lock){..-.}-{2:2}, at: free_ioctx_users+0x30/0x1c0 [ 43.366775][ C0] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 43.374290][ C0] (&pid->wait_pidfd){+.+.}-{2:2} [ 43.374296][ C0] [ 43.374296][ C0] [ 43.374296][ C0] and interrupts could create inverse lock ordering between them. [ 43.374296][ C0] [ 43.393594][ C0] [ 43.393594][ C0] other info that might help us debug this: [ 43.403451][ C0] Possible interrupt unsafe locking scenario: [ 43.403451][ C0] [ 43.411741][ C0] CPU0 CPU1 [ 43.417087][ C0] ---- ---- [ 43.422562][ C0] lock(&pid->wait_pidfd); [ 43.427217][ C0] local_irq_disable(); [ 43.434124][ C0] lock(&ctx->ctx_lock); [ 43.441095][ C0] lock(&pid->wait_pidfd); [ 43.448095][ C0] [ 43.451534][ C0] lock(&ctx->ctx_lock); [ 43.456037][ C0] [ 43.456037][ C0] *** DEADLOCK *** [ 43.456037][ C0] [ 43.465683][ C0] 2 locks held by swapper/0/0: [ 43.470417][ C0] #0: ffffffff892e6c20 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire+0x0/0x30 [ 43.479710][ C0] #1: ffffffff892e6bd0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 [ 43.489238][ C0] [ 43.489238][ C0] the shortest dependencies between 2nd lock and 1st lock: [ 43.498830][ C0] -> (&pid->wait_pidfd){+.+.}-{2:2} { [ 43.504296][ C0] HARDIRQ-ON-W at: [ 43.508347][ C0] lock_acquire+0x169/0x480 [ 43.514669][ C0] _raw_spin_lock+0x2a/0x40 [ 43.521101][ C0] proc_pid_make_inode+0x187/0x2d0 [ 43.528009][ C0] proc_pid_instantiate+0x4b/0x1a0 [ 43.535000][ C0] proc_pid_lookup+0x218/0x2f0 [ 43.541644][ C0] proc_root_lookup+0x1b/0x50 [ 43.548114][ C0] __lookup_slow+0x240/0x370 [ 43.554584][ C0] walk_component+0x442/0x680 [ 43.561162][ C0] link_path_walk+0x66d/0xba0 [ 43.567658][ C0] path_openat+0x21d/0x38b0 [ 43.573956][ C0] do_filp_open+0x191/0x3a0 [ 43.580561][ C0] do_sys_openat2+0x463/0x770 [ 43.587158][ C0] __x64_sys_open+0x1af/0x1e0 [ 43.593817][ C0] do_syscall_64+0xf3/0x1b0 [ 43.600270][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 43.607984][ C0] SOFTIRQ-ON-W at: [ 43.612036][ C0] lock_acquire+0x169/0x480 [ 43.618369][ C0] _raw_spin_lock+0x2a/0x40 [ 43.624675][ C0] proc_pid_make_inode+0x187/0x2d0 [ 43.631816][ C0] proc_pid_instantiate+0x4b/0x1a0 [ 43.638743][ C0] proc_pid_lookup+0x218/0x2f0 [ 43.645331][ C0] proc_root_lookup+0x1b/0x50 [ 43.651814][ C0] __lookup_slow+0x240/0x370 [ 43.658218][ C0] walk_component+0x442/0x680 [ 43.664701][ C0] link_path_walk+0x66d/0xba0 [ 43.671413][ C0] path_openat+0x21d/0x38b0 [ 43.677729][ C0] do_filp_open+0x191/0x3a0 [ 43.684028][ C0] do_sys_openat2+0x463/0x770 [ 43.690651][ C0] __x64_sys_open+0x1af/0x1e0 [ 43.697244][ C0] do_syscall_64+0xf3/0x1b0 [ 43.703564][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 43.711262][ C0] INITIAL USE at: [ 43.715237][ C0] lock_acquire+0x169/0x480 [ 43.721456][ C0] _raw_spin_lock_irqsave+0x9e/0xc0 [ 43.728504][ C0] __wake_up+0xb8/0x150 [ 43.734433][ C0] do_notify_parent+0x167/0xce0 [ 43.741140][ C0] do_exit+0x12c5/0x1f80 [ 43.747106][ C0] call_usermodehelper_exec_async+0x47c/0x480 [ 43.754894][ C0] ret_from_fork+0x24/0x30 [ 43.761558][ C0] } [ 43.764124][ C0] ... key at: [] alloc_pid.__key+0x0/0x10 [ 43.771988][ C0] ... acquired at: [ 43.775852][ C0] lock_acquire+0x169/0x480 [ 43.780713][ C0] _raw_spin_lock+0x2a/0x40 [ 43.785731][ C0] io_submit_one+0x10f5/0x1a80 [ 43.790742][ C0] __se_sys_io_submit+0x117/0x220 [ 43.795929][ C0] do_syscall_64+0xf3/0x1b0 [ 43.800584][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 43.806621][ C0] [ 43.808956][ C0] -> (&ctx->ctx_lock){..-.}-{2:2} { [ 43.814223][ C0] IN-SOFTIRQ-W at: [ 43.818178][ C0] lock_acquire+0x169/0x480 [ 43.824320][ C0] _raw_spin_lock_irq+0x67/0x80 [ 43.830809][ C0] free_ioctx_users+0x30/0x1c0 [ 43.837344][ C0] percpu_ref_put+0x18d/0x1a0 [ 43.843649][ C0] rcu_core+0x816/0x1120 [ 43.849612][ C0] __do_softirq+0x268/0x80c [ 43.855752][ C0] irq_exit+0x223/0x230 [ 43.861644][ C0] smp_apic_timer_interrupt+0x113/0x280 [ 43.868831][ C0] apic_timer_interrupt+0xf/0x20 [ 43.875488][ C0] native_safe_halt+0xe/0x10 [ 43.881715][ C0] default_idle+0x4c/0x70 [ 43.887804][ C0] do_idle+0x1ee/0x650 [ 43.893512][ C0] cpu_startup_entry+0x15/0x20 [ 43.900097][ C0] start_kernel+0x674/0x774 [ 43.906261][ C0] secondary_startup_64+0xa4/0xb0 [ 43.913051][ C0] INITIAL USE at: [ 43.916933][ C0] lock_acquire+0x169/0x480 [ 43.923157][ C0] _raw_spin_lock_irq+0x67/0x80 [ 43.929831][ C0] io_submit_one+0x10cb/0x1a80 [ 43.936253][ C0] __se_sys_io_submit+0x117/0x220 [ 43.943960][ C0] do_syscall_64+0xf3/0x1b0 [ 43.950019][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 43.957457][ C0] } [ 43.959942][ C0] ... key at: [] ioctx_alloc.__key+0x0/0x10 [ 43.968115][ C0] ... acquired at: [ 43.972012][ C0] mark_lock+0x529/0x1b00 [ 43.976489][ C0] __lock_acquire+0xaa7/0x2b90 [ 43.981604][ C0] lock_acquire+0x169/0x480 [ 43.987897][ C0] _raw_spin_lock_irq+0x67/0x80 [ 43.993044][ C0] free_ioctx_users+0x30/0x1c0 [ 43.998162][ C0] percpu_ref_put+0x18d/0x1a0 [ 44.003494][ C0] rcu_core+0x816/0x1120 [ 44.007889][ C0] __do_softirq+0x268/0x80c [ 44.012551][ C0] irq_exit+0x223/0x230 [ 44.016878][ C0] smp_apic_timer_interrupt+0x113/0x280 [ 44.022659][ C0] apic_timer_interrupt+0xf/0x20 [ 44.027856][ C0] native_safe_halt+0xe/0x10 [ 44.032598][ C0] default_idle+0x4c/0x70 [ 44.037084][ C0] do_idle+0x1ee/0x650 [ 44.041397][ C0] cpu_startup_entry+0x15/0x20 [ 44.046307][ C0] start_kernel+0x674/0x774 [ 44.050957][ C0] secondary_startup_64+0xa4/0xb0 [ 44.056316][ C0] [ 44.058629][ C0] [ 44.058629][ C0] stack backtrace: [ 44.064493][ C0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-syzkaller #0 [ 44.072012][ C0] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 44.082493][ C0] Call Trace: [ 44.085783][ C0] [ 44.088643][ C0] dump_stack+0x1e9/0x30e [ 44.093138][ C0] print_irq_inversion_bug+0xb67/0xe90 [ 44.098869][ C0] ? arch_stack_walk+0xb4/0xe0 [ 44.103608][ C0] ? secondary_startup_64+0xa4/0xb0 [ 44.108788][ C0] check_usage_forwards+0x13f/0x240 [ 44.113959][ C0] ? save_trace+0x49/0xb60 [ 44.118350][ C0] mark_lock+0x529/0x1b00 [ 44.122649][ C0] ? check_usage_backwards+0x240/0x240 [ 44.128098][ C0] ? mark_lock+0x102/0x1b00 [ 44.132574][ C0] ? __lock_acquire+0x116c/0x2b90 [ 44.137568][ C0] __lock_acquire+0xaa7/0x2b90 [ 44.142584][ C0] ? pcpu_block_update+0x564/0x890 [ 44.147683][ C0] lock_acquire+0x169/0x480 [ 44.152638][ C0] ? free_ioctx_users+0x30/0x1c0 [ 44.157554][ C0] ? rcu_lock_acquire+0x5/0x30 [ 44.162310][ C0] ? trace_irq_disable_rcuidle+0x1f/0x1d0 [ 44.168063][ C0] ? percpu_ref_noop_confirm_switch+0x10/0x10 [ 44.174132][ C0] _raw_spin_lock_irq+0x67/0x80 [ 44.178960][ C0] ? free_ioctx_users+0x30/0x1c0 [ 44.183866][ C0] free_ioctx_users+0x30/0x1c0 [ 44.188607][ C0] ? percpu_ref_noop_confirm_switch+0x10/0x10 [ 44.194743][ C0] ? percpu_ref_noop_confirm_switch+0x10/0x10 [ 44.200825][ C0] percpu_ref_put+0x18d/0x1a0 [ 44.205504][ C0] rcu_core+0x816/0x1120 [ 44.210453][ C0] __do_softirq+0x268/0x80c [ 44.215040][ C0] ? irq_exit+0x223/0x230 [ 44.219384][ C0] irq_exit+0x223/0x230 [ 44.223626][ C0] smp_apic_timer_interrupt+0x113/0x280 [ 44.229147][ C0] apic_timer_interrupt+0xf/0x20 [ 44.234056][ C0] [ 44.236969][ C0] RIP: 0010:native_safe_halt+0xe/0x10 [ 44.242573][ C0] Code: 80 e1 07 80 c1 03 38 c1 7c bc 48 89 df e8 4a 29 a7 f9 eb b2 cc cc cc cc cc cc cc cc e9 07 00 00 00 0f 00 2d 36 c3 58 00 fb f4 90 e9 07 00 00 00 0f 00 2d 26 c3 58 00 f4 c3 cc cc 41 56 53 65 [ 44.262743][ C0] RSP: 0018:ffffffff89207e68 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 [ 44.271358][ C0] RAX: 1ffffffff1257409 RBX: ffffffff89281b00 RCX: dffffc0000000000 [ 44.279330][ C0] RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffffffff89282364 [ 44.287376][ C0] RBP: ffffffff896b9ee0 R08: ffffffff8178ec90 R09: fffffbfff1250361 [ 44.296415][ C0] R10: fffffbfff1250361 R11: 0000000000000000 R12: 1ffffffff1250360 [ 44.305319][ C0] R13: dffffc0000000000 R14: 1ffffffff1257407 R15: 0000000000000000 [ 44.313355][ C0] ? trace_hardirqs_on+0x30/0x70 [ 44.318382][ C0] default_idle+0x4c/0x70 [ 44.323466][ C0] do