[ 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... [ OK ] Started Update UTMP about System Runlevel Changes. Starting Load/Save RF Kill Switch Status... [ OK ] Started Load/Save RF Kill Switch Status. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.1.18' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 44.094257][ C0] [ 44.096603][ C0] ======================================================== [ 44.103829][ C0] WARNING: possible irq lock inversion dependency detected [ 44.111121][ C0] 5.6.0-syzkaller #0 Not tainted [ 44.116029][ C0] -------------------------------------------------------- [ 44.123205][ C0] swapper/0/0 just changed the state of lock: [ 44.129241][ C0] ffff888092c6dcd8 (&ctx->ctx_lock){..-.}-{2:2}, at: free_ioctx_users+0x30/0x1c0 [ 44.138340][ C0] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 44.145865][ C0] (&pid->wait_pidfd){+.+.}-{2:2} [ 44.145872][ C0] [ 44.145872][ C0] [ 44.145872][ C0] and interrupts could create inverse lock ordering between them. [ 44.145872][ C0] [ 44.165959][ C0] [ 44.165959][ C0] other info that might help us debug this: [ 44.174004][ C0] Possible interrupt unsafe locking scenario: [ 44.174004][ C0] [ 44.182308][ C0] CPU0 CPU1 [ 44.187666][ C0] ---- ---- [ 44.193005][ C0] lock(&pid->wait_pidfd); [ 44.197475][ C0] local_irq_disable(); [ 44.204213][ C0] lock(&ctx->ctx_lock); [ 44.211045][ C0] lock(&pid->wait_pidfd); [ 44.218048][ C0] [ 44.221485][ C0] lock(&ctx->ctx_lock); [ 44.226019][ C0] [ 44.226019][ C0] *** DEADLOCK *** [ 44.226019][ C0] [ 44.234159][ C0] 2 locks held by swapper/0/0: [ 44.239040][ C0] #0: ffffffff892e6be0 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire+0x0/0x30 [ 44.248223][ C0] #1: ffffffff892e6b90 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x5/0x30 [ 44.257489][ C0] [ 44.257489][ C0] the shortest dependencies between 2nd lock and 1st lock: [ 44.267005][ C0] -> (&pid->wait_pidfd){+.+.}-{2:2} { [ 44.272474][ C0] HARDIRQ-ON-W at: [ 44.276535][ C0] lock_acquire+0x169/0x480 [ 44.282859][ C0] _raw_spin_lock+0x2a/0x40 [ 44.289337][ C0] proc_pid_make_inode+0x187/0x2d0 [ 44.296404][ C0] proc_pid_instantiate+0x4b/0x1a0 [ 44.303319][ C0] proc_pid_lookup+0x218/0x2f0 [ 44.309879][ C0] proc_root_lookup+0x1b/0x50 [ 44.316539][ C0] __lookup_slow+0x240/0x370 [ 44.322962][ C0] walk_component+0x442/0x680 [ 44.329449][ C0] link_path_walk+0x66d/0xba0 [ 44.335940][ C0] path_openat+0x21d/0x38b0 [ 44.342262][ C0] do_filp_open+0x191/0x3a0 [ 44.348580][ C0] do_sys_openat2+0x463/0x770 [ 44.355074][ C0] __x64_sys_open+0x1af/0x1e0 [ 44.361827][ C0] do_syscall_64+0xf3/0x1b0 [ 44.368383][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 44.376094][ C0] SOFTIRQ-ON-W at: [ 44.380155][ C0] lock_acquire+0x169/0x480 [ 44.386464][ C0] _raw_spin_lock+0x2a/0x40 [ 44.392763][ C0] proc_pid_make_inode+0x187/0x2d0 [ 44.399671][ C0] proc_pid_instantiate+0x4b/0x1a0 [ 44.406701][ C0] proc_pid_lookup+0x218/0x2f0 [ 44.413419][ C0] proc_root_lookup+0x1b/0x50 [ 44.419894][ C0] __lookup_slow+0x240/0x370 [ 44.426280][ C0] walk_component+0x442/0x680 [ 44.432751][ C0] link_path_walk+0x66d/0xba0 [ 44.439225][ C0] path_openat+0x21d/0x38b0 [ 44.445544][ C0] do_filp_open+0x191/0x3a0 [ 44.451948][ C0] do_sys_openat2+0x463/0x770 [ 44.458422][ C0] __x64_sys_open+0x1af/0x1e0 [ 44.464922][ C0] do_syscall_64+0xf3/0x1b0 [ 44.471247][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 44.478933][ C0] INITIAL USE at: [ 44.482917][ C0] lock_acquire+0x169/0x480 [ 44.489164][ C0] _raw_spin_lock_irqsave+0x9e/0xc0 [ 44.496080][ C0] __wake_up+0xb8/0x150 [ 44.501948][ C0] do_notify_parent+0x167/0xce0 [ 44.508509][ C0] do_exit+0x12c5/0x1f80 [ 44.514478][ C0] call_usermodehelper_exec_async+0x47c/0x480 [ 44.522255][ C0] ret_from_fork+0x24/0x30 [ 44.528422][ C0] } [ 44.531009][ C0] ... key at: [] alloc_pid.__key+0x0/0x10 [ 44.538885][ C0] ... acquired at: [ 44.542769][ C0] lock_acquire+0x169/0x480 [ 44.547435][ C0] _raw_spin_lock+0x2a/0x40 [ 44.552099][ C0] io_submit_one+0x10f5/0x1a80 [ 44.557056][ C0] __se_sys_io_submit+0x117/0x220 [ 44.562239][ C0] do_syscall_64+0xf3/0x1b0 [ 44.566893][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 44.573055][ C0] [ 44.575479][ C0] -> (&ctx->ctx_lock){..-.}-{2:2} { [ 44.580670][ C0] IN-SOFTIRQ-W at: [ 44.584637][ C0] lock_acquire+0x169/0x480 [ 44.590778][ C0] _raw_spin_lock_irq+0x67/0x80 [ 44.597265][ C0] free_ioctx_users+0x30/0x1c0 [ 44.603688][ C0] percpu_ref_put+0x18d/0x1a0 [ 44.610108][ C0] rcu_core+0x816/0x1120 [ 44.616106][ C0] __do_softirq+0x268/0x80c [ 44.622362][ C0] irq_exit+0x223/0x230 [ 44.628162][ C0] smp_apic_timer_interrupt+0x113/0x280 [ 44.635467][ C0] apic_timer_interrupt+0xf/0x20 [ 44.642379][ C0] native_safe_halt+0xe/0x10 [ 44.648655][ C0] default_idle+0x4c/0x70 [ 44.654619][ C0] do_idle+0x1ee/0x650 [ 44.660317][ C0] cpu_startup_entry+0x15/0x20 [ 44.666738][ C0] start_kernel+0x674/0x774 [ 44.672871][ C0] secondary_startup_64+0xa4/0xb0 [ 44.679515][ C0] INITIAL USE at: [ 44.683385][ C0] lock_acquire+0x169/0x480 [ 44.689426][ C0] _raw_spin_lock_irq+0x67/0x80 [ 44.695816][ C0] io_submit_one+0x10cb/0x1a80 [ 44.702123][ C0] __se_sys_io_submit+0x117/0x220 [ 44.708696][ C0] do_syscall_64+0xf3/0x1b0 [ 44.714754][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 44.722178][ C0] } [ 44.724677][ C0] ... key at: [] ioctx_alloc.__key+0x0/0x10 [ 44.732648][ C0] ... acquired at: [ 44.736447][ C0] mark_lock+0x529/0x1b00 [ 44.740926][ C0] __lock_acquire+0xaa7/0x2b90 [ 44.745839][ C0] lock_acquire+0x169/0x480 [ 44.750495][ C0] _raw_spin_lock_irq+0x67/0x80 [ 44.755503][ C0] free_ioctx_users+0x30/0x1c0 [ 44.760412][ C0] percpu_ref_put+0x18d/0x1a0 [ 44.765242][ C0] rcu_core+0x816/0x1120 [ 44.769721][ C0] __do_softirq+0x268/0x80c [ 44.774377][ C0] irq_exit+0x223/0x230 [ 44.778699][ C0] smp_apic_timer_interrupt+0x113/0x280 [ 44.784409][ C0] apic_timer_interrupt+0xf/0x20 [ 44.789497][ C0] native_safe_halt+0xe/0x10 [ 44.794248][ C0] default_idle+0x4c/0x70 [ 44.798835][ C0] do_idle+0x1ee/0x650 [ 44.803048][ C0] cpu_startup_entry+0x15/0x20 [ 44.807961][ C0] start_kernel+0x674/0x774 [ 44.812610][ C0] secondary_startup_64+0xa4/0xb0 [ 44.817776][ C0] [ 44.820091][ C0] [ 44.820091][ C0] stack backtrace: [ 44.825956][ C0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-syzkaller #0 [ 44.833639][ C0] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 44.843683][ C0] Call Trace: [ 44.846952][ C0] [ 44.849781][ C0] dump_stack+0x1e9/0x30e [ 44.854086][ C0] print_irq_inversion_bug+0xb67/0xe90 [ 44.859606][ C0] ? arch_stack_walk+0xb4/0xe0 [ 44.864345][ C0] ? secondary_startup_64+0xa4/0xb0 [ 44.869687][ C0] check_usage_forwards+0x13f/0x240 [ 44.874878][ C0] ? save_trace+0x49/0xb60 [ 44.879268][ C0] mark_lock+0x529/0x1b00 [ 44.883578][ C0] ? check_usage_backwards+0x240/0x240 [ 44.889404][ C0] ? mark_lock+0x102/0x1b00 [ 44.893894][ C0] ? __lock_acquire+0x116c/0x2b90 [ 44.898955][ C0] __lock_acquire+0xaa7/0x2b90 [ 44.903699][ C0] ? pcpu_block_update+0x564/0x890 [ 44.908800][ C0] lock_acquire+0x169/0x480 [ 44.913276][ C0] ? free_ioctx_users+0x30/0x1c0 [ 44.918189][ C0] ? rcu_lock_acquire+0x5/0x30 [ 44.922942][ C0] ? trace_irq_disable_rcuidle+0x1f/0x1d0 [ 44.928656][ C0] ? percpu_ref_noop_confirm_switch+0x10/0x10 [ 44.935187][ C0] _raw_spin_lock_irq+0x67/0x80 [ 44.940042][ C0] ? free_ioctx_users+0x30/0x1c0 [ 44.945038][ C0] free_ioctx_users+0x30/0x1c0 [ 44.949776][ C0] ? percpu_ref_noop_confirm_switch+0x10/0x10 [ 44.955814][ C0] ? percpu_ref_noop_confirm_switch+0x10/0x10 [ 44.961850][ C0] percpu_ref_put+0x18d/0x1a0 [ 44.966517][ C0] rcu_core+0x816/0x1120 [ 44.970732][ C0] __do_softirq+0x268/0x80c [ 44.975210][ C0] ? irq_exit+0x223/0x230 [ 44.979586][ C0] irq_exit+0x223/0x230 [ 44.983738][ C0] smp_apic_timer_interrupt+0x113/0x280 [ 44.989290][ C0] apic_timer_interrupt+0xf/0x20 [ 44.994206][ C0] [ 44.997144][ C0] RIP: 0010:native_safe_halt+0xe/0x10 [ 45.002589][ C0] Code: 80 e1 07 80 c1 03 38 c1 7c bc 48 89 df e8 aa 1f a8 f9 eb b2 cc cc cc cc cc cc cc cc e9 07 00 00 00 0f 00 2d 96 04 57 00 fb f4 90 e9 07 00 00 00 0f 00 2d 86 04 57 00 f4 c3 cc cc 41 56 53 65 [ 45.022269][ C0] RSP: 0018:ffffffff89207e68 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 [ 45.030672][ C0] RAX: 1ffffffff1257401 RBX: ffffffff89281b00 RCX: dffffc0000000000 [ 45.038924][ C0] RDX: dffffc0000000000 RSI: 0000000000000000 RDI: ffffffff89282364 [ 45.046888][ C0] RBP: ffffffff896b99a0 R08: ffffffff817b9ae0 R09: fffffbfff1250361 [ 45.054849][ C0] R10: fffffbfff1250361 R11: 0000000000000000 R12: 1ffffffff1250360 [ 45.062807][ C0] R13: dffffc0000000000 R14: 1ffffffff12573ff R15: 0000000000000000 [ 45.070766][ C0] ? trace_hardirqs_on+0x30/0x70 [ 45.075695][ C0] default_idle+0x4c/0x70 [ 45.080028][ C0] do_idle+0x1ee/0x650 [ 45.084089][ C0] cpu_startup_entry+0x15/0x20 [ 45.088832][ C0] ? time_init+0x33/0x33 [ 45.093065][ C0] start_kernel+0x674/0x774 [ 45.097660][ C0] secondary_startup_64+0xa4/0xb0