[ OK ] Started Getty on tty4. [ OK ] Started Getty on tty3. [ 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 '10.128.0.167' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 58.671399][ C0] [ 58.673864][ C0] ======================================================== [ 58.681147][ C0] WARNING: possible irq lock inversion dependency detected [ 58.688583][ C0] 5.6.0-syzkaller #0 Not tainted [ 58.693678][ C0] -------------------------------------------------------- [ 58.700864][ C0] swapper/0/0 just changed the state of lock: [ 58.706939][ C0] ffff88809462dcd8 (&ctx->ctx_lock){..-.}-{2:2}, at: free_ioctx_users+0x2b/0x450 [ 58.716075][ C0] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 58.723598][ C0] (&pid->wait_pidfd){+.+.}-{2:2} [ 58.723610][ C0] [ 58.723610][ C0] [ 58.723610][ C0] and interrupts could create inverse lock ordering between them. [ 58.723610][ C0] [ 58.742934][ C0] [ 58.742934][ C0] other info that might help us debug this: [ 58.751171][ C0] Possible interrupt unsafe locking scenario: [ 58.751171][ C0] [ 58.759675][ C0] CPU0 CPU1 [ 58.765048][ C0] ---- ---- [ 58.770551][ C0] lock(&pid->wait_pidfd); [ 58.775077][ C0] local_irq_disable(); [ 58.781829][ C0] lock(&ctx->ctx_lock); [ 58.788670][ C0] lock(&pid->wait_pidfd); [ 58.795711][ C0] [ 58.799196][ C0] lock(&ctx->ctx_lock); [ 58.803707][ C0] [ 58.803707][ C0] *** DEADLOCK *** [ 58.803707][ C0] [ 58.811863][ C0] 2 locks held by swapper/0/0: [ 58.816607][ C0] #0: ffffffff899bc060 (rcu_callback){....}-{0:0}, at: rcu_core+0x520/0x1370 [ 58.825631][ C0] #1: ffffffff899bc180 (rcu_read_lock){....}-{1:2}, at: percpu_ref_switch_to_atomic_rcu+0x209/0x540 [ 58.836493][ C0] [ 58.836493][ C0] the shortest dependencies between 2nd lock and 1st lock: [ 58.846091][ C0] -> (&pid->wait_pidfd){+.+.}-{2:2} { [ 58.851537][ C0] HARDIRQ-ON-W at: [ 58.855595][ C0] lock_acquire+0x1f2/0x8f0 [ 58.861942][ C0] _raw_spin_lock+0x2a/0x40 [ 58.868267][ C0] proc_pid_make_inode+0x1f9/0x3c0 [ 58.875790][ C0] proc_pid_instantiate+0x51/0x150 [ 58.882708][ C0] proc_pid_lookup+0x1da/0x340 [ 58.889285][ C0] proc_root_lookup+0x20/0x60 [ 58.895763][ C0] __lookup_slow+0x256/0x490 [ 58.902250][ C0] walk_component+0x418/0x6a0 [ 58.908737][ C0] link_path_walk.part.0+0x4f1/0xb50 [ 58.915844][ C0] path_openat+0x25a/0x27d0 [ 58.922332][ C0] do_filp_open+0x192/0x260 [ 58.928646][ C0] do_sys_openat2+0x585/0x7d0 [ 58.935134][ C0] do_sys_open+0xc3/0x140 [ 58.941263][ C0] do_syscall_64+0xf6/0x7d0 [ 58.947582][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 58.955290][ C0] SOFTIRQ-ON-W at: [ 58.959350][ C0] lock_acquire+0x1f2/0x8f0 [ 58.965665][ C0] _raw_spin_lock+0x2a/0x40 [ 58.972068][ C0] proc_pid_make_inode+0x1f9/0x3c0 [ 58.979005][ C0] proc_pid_instantiate+0x51/0x150 [ 58.985927][ C0] proc_pid_lookup+0x1da/0x340 [ 58.992489][ C0] proc_root_lookup+0x20/0x60 [ 58.998975][ C0] __lookup_slow+0x256/0x490 [ 59.005372][ C0] walk_component+0x418/0x6a0 [ 59.011860][ C0] link_path_walk.part.0+0x4f1/0xb50 [ 59.018951][ C0] path_openat+0x25a/0x27d0 [ 59.025261][ C0] do_filp_open+0x192/0x260 [ 59.031563][ C0] do_sys_openat2+0x585/0x7d0 [ 59.038095][ C0] do_sys_open+0xc3/0x140 [ 59.044224][ C0] do_syscall_64+0xf6/0x7d0 [ 59.050739][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 59.058755][ C0] INITIAL USE at: [ 59.062768][ C0] lock_acquire+0x1f2/0x8f0 [ 59.069004][ C0] _raw_spin_lock_irqsave+0x8c/0xbf [ 59.076234][ C0] __wake_up_common_lock+0xb4/0x130 [ 59.083156][ C0] do_notify_parent+0x19e/0xe60 [ 59.089743][ C0] do_exit+0x238f/0x2dd0 [ 59.096425][ C0] call_usermodehelper_exec_async+0x507/0x710 [ 59.104222][ C0] ret_from_fork+0x24/0x30 [ 59.110624][ C0] } [ 59.113208][ C0] ... key at: [] __key.53831+0x0/0x40 [ 59.120738][ C0] ... acquired at: [ 59.124625][ C0] _raw_spin_lock+0x2a/0x40 [ 59.129289][ C0] io_submit_one+0xc1b/0x2ec0 [ 59.134136][ C0] __ia32_compat_sys_io_submit+0x1bf/0x530 [ 59.140098][ C0] do_fast_syscall_32+0x270/0xe90 [ 59.145284][ C0] entry_SYSENTER_compat+0x70/0x7f [ 59.150550][ C0] [ 59.152968][ C0] -> (&ctx->ctx_lock){..-.}-{2:2} { [ 59.158439][ C0] IN-SOFTIRQ-W at: [ 59.163097][ C0] lock_acquire+0x1f2/0x8f0 [ 59.169225][ C0] _raw_spin_lock_irq+0x5b/0x80 [ 59.175716][ C0] free_ioctx_users+0x2b/0x450 [ 59.182214][ C0] percpu_ref_switch_to_atomic_rcu+0x494/0x540 [ 59.190016][ C0] rcu_core+0x59f/0x1370 [ 59.195895][ C0] __do_softirq+0x26c/0x9f7 [ 59.202036][ C0] irq_exit+0x192/0x1d0 [ 59.207828][ C0] smp_apic_timer_interrupt+0x19e/0x600 [ 59.216661][ C0] apic_timer_interrupt+0xf/0x20 [ 59.223245][ C0] native_safe_halt+0xe/0x10 [ 59.229569][ C0] default_idle+0x49/0x350 [ 59.235699][ C0] do_idle+0x393/0x690 [ 59.241408][ C0] cpu_startup_entry+0x14/0x20 [ 59.247810][ C0] start_kernel+0x867/0x8a1 [ 59.253955][ C0] secondary_startup_64+0xa4/0xb0 [ 59.260619][ C0] INITIAL USE at: [ 59.264506][ C0] lock_acquire+0x1f2/0x8f0 [ 59.270612][ C0] _raw_spin_lock_irq+0x5b/0x80 [ 59.277056][ C0] io_submit_one+0xbd6/0x2ec0 [ 59.283288][ C0] __ia32_compat_sys_io_submit+0x1bf/0x530 [ 59.290656][ C0] do_fast_syscall_32+0x270/0xe90 [ 59.297226][ C0] entry_SYSENTER_compat+0x70/0x7f [ 59.303922][ C0] } [ 59.306447][ C0] ... key at: [] __key.55314+0x0/0x40 [ 59.313932][ C0] ... acquired at: [ 59.317736][ C0] mark_lock+0x624/0xf10 [ 59.322254][ C0] __lock_acquire+0x1d28/0x4e00 [ 59.327265][ C0] lock_acquire+0x1f2/0x8f0 [ 59.331963][ C0] _raw_spin_lock_irq+0x5b/0x80 [ 59.336989][ C0] free_ioctx_users+0x2b/0x450 [ 59.341919][ C0] percpu_ref_switch_to_atomic_rcu+0x494/0x540 [ 59.348230][ C0] rcu_core+0x59f/0x1370 [ 59.352636][ C0] __do_softirq+0x26c/0x9f7 [ 59.357335][ C0] irq_exit+0x192/0x1d0 [ 59.362452][ C0] smp_apic_timer_interrupt+0x19e/0x600 [ 59.368148][ C0] apic_timer_interrupt+0xf/0x20 [ 59.373234][ C0] native_safe_halt+0xe/0x10 [ 59.377972][ C0] default_idle+0x49/0x350 [ 59.382552][ C0] do_idle+0x393/0x690 [ 59.387573][ C0] cpu_startup_entry+0x14/0x20 [ 59.392506][ C0] start_kernel+0x867/0x8a1 [ 59.397176][ C0] secondary_startup_64+0xa4/0xb0 [ 59.402389][ C0] [ 59.404703][ C0] [ 59.404703][ C0] stack backtrace: [ 59.410576][ C0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-syzkaller #0 [ 59.418355][ C0] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 59.428912][ C0] Call Trace: [ 59.432204][ C0] [ 59.435077][ C0] dump_stack+0x188/0x20d [ 59.439392][ C0] check_usage_forwards.cold+0x20/0x29 [ 59.444833][ C0] ? check_usage_backwards+0x4e0/0x4e0 [ 59.450273][ C0] ? stack_trace_consume_entry+0x160/0x160 [ 59.456061][ C0] ? __read_once_size_nocheck.constprop.0+0x10/0x10 [ 59.462773][ C0] ? save_trace+0x42/0x9f0 [ 59.467193][ C0] mark_lock+0x624/0xf10 [ 59.471433][ C0] ? check_usage_backwards+0x4e0/0x4e0 [ 59.476964][ C0] ? print_usage_bug+0x240/0x240 [ 59.481938][ C0] ? print_usage_bug+0x240/0x240 [ 59.486858][ C0] ? mark_lock+0x12b/0xf10 [ 59.491278][ C0] __lock_acquire+0x1d28/0x4e00 [ 59.496133][ C0] ? mark_held_locks+0xe0/0xe0 [ 59.500888][ C0] ? __wake_up_common_lock+0xde/0x130 [ 59.506474][ C0] lock_acquire+0x1f2/0x8f0 [ 59.510959][ C0] ? free_ioctx_users+0x2b/0x450 [ 59.516257][ C0] ? lock_release+0x800/0x800 [ 59.520910][ C0] ? lock_acquire+0x1f2/0x8f0 [ 59.526616][ C0] ? percpu_ref_switch_to_atomic_rcu+0x209/0x540 [ 59.533612][ C0] ? lock_release+0x800/0x800 [ 59.538326][ C0] ? _raw_spin_unlock_irqrestore+0x62/0xe0 [ 59.544473][ C0] _raw_spin_lock_irq+0x5b/0x80 [ 59.549600][ C0] ? free_ioctx_users+0x2b/0x450 [ 59.556489][ C0] free_ioctx_users+0x2b/0x450 [ 59.562620][ C0] percpu_ref_switch_to_atomic_rcu+0x494/0x540 [ 59.569633][ C0] rcu_core+0x59f/0x1370 [ 59.573859][ C0] ? __rcu_read_unlock+0x700/0x700 [ 59.579031][ C0] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 59.584561][ C0] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 59.590602][ C0] ? run_rebalance_domains+0x202/0x2c0 [ 59.596038][ C0] __do_softirq+0x26c/0x9f7 [ 59.600526][ C0] irq_exit+0x192/0x1d0 [ 59.604659][ C0] smp_apic_timer_interrupt+0x19e/0x600 [ 59.610201][ C0] apic_timer_interrupt+0xf/0x20 [ 59.615109][ C0] [ 59.618035][ C0] RIP: 0010:native_safe_halt+0xe/0x10 [ 59.623380][ C0] Code: cc cc cc cc cc cc cc cc cc cc cc cc e9 07 00 00 00 0f 00 2d 84 1e 59 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 74 1e 59 00 fb f4 cc 41 56 41 55 41 54 55 53 e8 83 91 91 f9 e8 ce 2c ca fb 0f 1f [ 59.642959][ C0] RSP: 0018:ffffffff89807d98 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 [ 59.651342][ C0] RAX: 1ffffffff132930f RBX: ffffffff898864c0 RCX: 0000000000000000 [ 59.659285][ C0] RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffffffff89886d84 [ 59.667249][ C0] RBP: dffffc0000000000 R08: ffffffff898864c0 R09: 0000000000000000 [ 59.675205][ C0] R10: 0000000000000000 R11: 0000000000000000 R12: fffffbfff1310c98 [ 59.683160][ C0] R13: 0000000000000000 R14: ffffffff8a890cc0 R15: 0000000000000000 [ 59.691130][ C0] default_idle+0x49/0x350 [ 59.695536][ C0] do_idle+0x393/0x690 [ 59.699610][ C0] ? rcu_read_lock_held+0x9c/0xb0 [ 59.704615][ C0] ? arch_cpu_idle_exit+0x70/0x70 [ 59.709617][ C0] ? schedule+0xe7/0x2a0 [ 59.713837][ C0] ? trace_init_perf_perm_irq_work_exit+0xe/0xe [ 59.720051][ C0] cpu_startup_entry+0x14/0x20 [ 59.724807][ C0] start_kernel+0x867/0x8a1 [ 59.729286][ C0] ? mem_encrypt_init+0x5/0x5 [ 59.733958][ C0] ? x86_family+0x3d/0x50 [ 59.738275][ C0] ? load_ucode_bsp+0x23d/0x27d [ 59.743103][ C0] secondary_startup_64+0xa4/0xb0