[ OK ] Started Getty on tty4. [ OK ] Started Getty on tty3. [ OK ] Started Getty on tty2. [ OK ] Started Serial Getty on ttyS0. [ OK ] Started Getty on tty1. [ 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. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.1.3' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 65.768388][ C0] [ 65.770821][ C0] ======================================================== [ 65.778000][ C0] WARNING: possible irq lock inversion dependency detected [ 65.785191][ C0] 5.6.0-syzkaller #0 Not tainted [ 65.790102][ C0] -------------------------------------------------------- [ 65.797278][ C0] swapper/0/0 just changed the state of lock: [ 65.803317][ C0] ffff888094f93cd8 (&ctx->ctx_lock){..-.}-{2:2}, at: free_ioctx_users+0x2b/0x450 [ 65.812425][ C0] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 65.819941][ C0] (&pid->wait_pidfd){+.+.}-{2:2} [ 65.819951][ C0] [ 65.819951][ C0] [ 65.819951][ C0] and interrupts could create inverse lock ordering between them. [ 65.819951][ C0] [ 65.839835][ C0] [ 65.839835][ C0] other info that might help us debug this: [ 65.847892][ C0] Possible interrupt unsafe locking scenario: [ 65.847892][ C0] [ 65.856223][ C0] CPU0 CPU1 [ 65.861589][ C0] ---- ---- [ 65.867044][ C0] lock(&pid->wait_pidfd); [ 65.871534][ C0] local_irq_disable(); [ 65.878463][ C0] lock(&ctx->ctx_lock); [ 65.885293][ C0] lock(&pid->wait_pidfd); [ 65.892301][ C0] [ 65.895731][ C0] lock(&ctx->ctx_lock); [ 65.900565][ C0] [ 65.900565][ C0] *** DEADLOCK *** [ 65.900565][ C0] [ 65.908871][ C0] 2 locks held by swapper/0/0: [ 65.913702][ C0] #0: ffffffff899bc060 (rcu_callback){....}-{0:0}, at: rcu_core+0x520/0x1370 [ 65.922640][ C0] #1: ffffffff899bc180 (rcu_read_lock){....}-{1:2}, at: percpu_ref_switch_to_atomic_rcu+0x209/0x540 [ 65.933614][ C0] [ 65.933614][ C0] the shortest dependencies between 2nd lock and 1st lock: [ 65.943275][ C0] -> (&pid->wait_pidfd){+.+.}-{2:2} { [ 65.948803][ C0] HARDIRQ-ON-W at: [ 65.952873][ C0] lock_acquire+0x1f2/0x8f0 [ 65.959196][ C0] _raw_spin_lock+0x2a/0x40 [ 65.965512][ C0] proc_pid_make_inode+0x1f9/0x3c0 [ 65.972437][ C0] proc_pid_instantiate+0x51/0x150 [ 65.979347][ C0] proc_pid_lookup+0x1da/0x340 [ 65.985917][ C0] proc_root_lookup+0x20/0x60 [ 65.992392][ C0] __lookup_slow+0x256/0x490 [ 65.998780][ C0] walk_component+0x418/0x6a0 [ 66.005264][ C0] link_path_walk.part.0+0x4f1/0xb50 [ 66.012442][ C0] path_openat+0x25a/0x27d0 [ 66.018764][ C0] do_filp_open+0x192/0x260 [ 66.025203][ C0] do_sys_openat2+0x585/0x7d0 [ 66.031708][ C0] do_sys_open+0xc3/0x140 [ 66.037873][ C0] do_syscall_64+0xf6/0x7d0 [ 66.044287][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 66.052003][ C0] SOFTIRQ-ON-W at: [ 66.056096][ C0] lock_acquire+0x1f2/0x8f0 [ 66.062510][ C0] _raw_spin_lock+0x2a/0x40 [ 66.068835][ C0] proc_pid_make_inode+0x1f9/0x3c0 [ 66.075834][ C0] proc_pid_instantiate+0x51/0x150 [ 66.082764][ C0] proc_pid_lookup+0x1da/0x340 [ 66.089444][ C0] proc_root_lookup+0x20/0x60 [ 66.096076][ C0] __lookup_slow+0x256/0x490 [ 66.102636][ C0] walk_component+0x418/0x6a0 [ 66.110093][ C0] link_path_walk.part.0+0x4f1/0xb50 [ 66.117192][ C0] path_openat+0x25a/0x27d0 [ 66.123615][ C0] do_filp_open+0x192/0x260 [ 66.130110][ C0] do_sys_openat2+0x585/0x7d0 [ 66.136640][ C0] do_sys_open+0xc3/0x140 [ 66.142926][ C0] do_syscall_64+0xf6/0x7d0 [ 66.149247][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 66.156934][ C0] INITIAL USE at: [ 66.160900][ C0] lock_acquire+0x1f2/0x8f0 [ 66.167129][ C0] _raw_spin_lock_irqsave+0x8c/0xbf [ 66.174049][ C0] __wake_up_common_lock+0xb4/0x130 [ 66.181078][ C0] do_notify_parent+0x19e/0xe60 [ 66.187766][ C0] do_exit+0x238f/0x2dd0 [ 66.193863][ C0] call_usermodehelper_exec_async+0x507/0x710 [ 66.201690][ C0] ret_from_fork+0x24/0x30 [ 66.207818][ C0] } [ 66.210389][ C0] ... key at: [] __key.53831+0x0/0x40 [ 66.217919][ C0] ... acquired at: [ 66.221800][ C0] _raw_spin_lock+0x2a/0x40 [ 66.226451][ C0] io_submit_one+0xc1b/0x2ec0 [ 66.231272][ C0] __ia32_compat_sys_io_submit+0x1bf/0x530 [ 66.237353][ C0] do_fast_syscall_32+0x270/0xe90 [ 66.242538][ C0] entry_SYSENTER_compat+0x70/0x7f [ 66.247817][ C0] [ 66.250159][ C0] -> (&ctx->ctx_lock){..-.}-{2:2} { [ 66.255335][ C0] IN-SOFTIRQ-W at: [ 66.259300][ C0] lock_acquire+0x1f2/0x8f0 [ 66.265435][ C0] _raw_spin_lock_irq+0x5b/0x80 [ 66.271923][ C0] free_ioctx_users+0x2b/0x450 [ 66.278348][ C0] percpu_ref_switch_to_atomic_rcu+0x494/0x540 [ 66.286252][ C0] rcu_core+0x59f/0x1370 [ 66.292132][ C0] __do_softirq+0x26c/0x9f7 [ 66.298269][ C0] irq_exit+0x192/0x1d0 [ 66.304066][ C0] smp_apic_timer_interrupt+0x19e/0x600 [ 66.311253][ C0] apic_timer_interrupt+0xf/0x20 [ 66.317821][ C0] native_safe_halt+0xe/0x10 [ 66.324188][ C0] default_idle+0x49/0x350 [ 66.330285][ C0] do_idle+0x393/0x690 [ 66.335996][ C0] cpu_startup_entry+0x14/0x20 [ 66.342396][ C0] start_kernel+0x867/0x8a1 [ 66.348545][ C0] secondary_startup_64+0xa4/0xb0 [ 66.355191][ C0] INITIAL USE at: [ 66.359070][ C0] lock_acquire+0x1f2/0x8f0 [ 66.365125][ C0] _raw_spin_lock_irq+0x5b/0x80 [ 66.371848][ C0] io_submit_one+0xbd6/0x2ec0 [ 66.378095][ C0] __ia32_compat_sys_io_submit+0x1bf/0x530 [ 66.385463][ C0] do_fast_syscall_32+0x270/0xe90 [ 66.392035][ C0] entry_SYSENTER_compat+0x70/0x7f [ 66.398687][ C0] } [ 66.401171][ C0] ... key at: [] __key.55314+0x0/0x40 [ 66.408602][ C0] ... acquired at: [ 66.412409][ C0] mark_lock+0x624/0xf10 [ 66.416803][ C0] __lock_acquire+0x1d28/0x4e00 [ 66.421818][ C0] lock_acquire+0x1f2/0x8f0 [ 66.426475][ C0] _raw_spin_lock_irq+0x5b/0x80 [ 66.431514][ C0] free_ioctx_users+0x2b/0x450 [ 66.437227][ C0] percpu_ref_switch_to_atomic_rcu+0x494/0x540 [ 66.443558][ C0] rcu_core+0x59f/0x1370 [ 66.447980][ C0] __do_softirq+0x26c/0x9f7 [ 66.452639][ C0] irq_exit+0x192/0x1d0 [ 66.456953][ C0] smp_apic_timer_interrupt+0x19e/0x600 [ 66.462830][ C0] apic_timer_interrupt+0xf/0x20 [ 66.467932][ C0] native_safe_halt+0xe/0x10 [ 66.472684][ C0] default_idle+0x49/0x350 [ 66.477369][ C0] do_idle+0x393/0x690 [ 66.481630][ C0] cpu_startup_entry+0x14/0x20 [ 66.486573][ C0] start_kernel+0x867/0x8a1 [ 66.491253][ C0] secondary_startup_64+0xa4/0xb0 [ 66.497119][ C0] [ 66.499436][ C0] [ 66.499436][ C0] stack backtrace: [ 66.505467][ C0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-syzkaller #0 [ 66.513166][ C0] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 66.523231][ C0] Call Trace: [ 66.526784][ C0] [ 66.529631][ C0] dump_stack+0x188/0x20d [ 66.533994][ C0] check_usage_forwards.cold+0x20/0x29 [ 66.539738][ C0] ? check_usage_backwards+0x4e0/0x4e0 [ 66.545406][ C0] ? stack_trace_consume_entry+0x160/0x160 [ 66.551390][ C0] ? __read_once_size_nocheck.constprop.0+0x10/0x10 [ 66.557988][ C0] ? save_trace+0x42/0x9f0 [ 66.562387][ C0] mark_lock+0x624/0xf10 [ 66.566636][ C0] ? check_usage_backwards+0x4e0/0x4e0 [ 66.573056][ C0] ? print_usage_bug+0x240/0x240 [ 66.577974][ C0] ? print_usage_bug+0x240/0x240 [ 66.582889][ C0] ? mark_lock+0x12b/0xf10 [ 66.587294][ C0] __lock_acquire+0x1d28/0x4e00 [ 66.592124][ C0] ? mark_held_locks+0xe0/0xe0 [ 66.597241][ C0] ? __wake_up_common_lock+0xde/0x130 [ 66.602700][ C0] lock_acquire+0x1f2/0x8f0 [ 66.607182][ C0] ? free_ioctx_users+0x2b/0x450 [ 66.612109][ C0] ? lock_release+0x800/0x800 [ 66.616760][ C0] ? lock_acquire+0x1f2/0x8f0 [ 66.621416][ C0] ? percpu_ref_switch_to_atomic_rcu+0x209/0x540 [ 66.627960][ C0] ? lock_release+0x800/0x800 [ 66.632620][ C0] ? _raw_spin_unlock_irqrestore+0x62/0xe0 [ 66.638406][ C0] _raw_spin_lock_irq+0x5b/0x80 [ 66.643259][ C0] ? free_ioctx_users+0x2b/0x450 [ 66.648290][ C0] free_ioctx_users+0x2b/0x450 [ 66.653072][ C0] percpu_ref_switch_to_atomic_rcu+0x494/0x540 [ 66.659215][ C0] rcu_core+0x59f/0x1370 [ 66.663443][ C0] ? __rcu_read_unlock+0x700/0x700 [ 66.668540][ C0] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 66.674073][ C0] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 66.680030][ C0] ? run_rebalance_domains+0x202/0x2c0 [ 66.685479][ C0] __do_softirq+0x26c/0x9f7 [ 66.689973][ C0] irq_exit+0x192/0x1d0 [ 66.694116][ C0] smp_apic_timer_interrupt+0x19e/0x600 [ 66.699836][ C0] apic_timer_interrupt+0xf/0x20 [ 66.704850][ C0] [ 66.707778][ C0] RIP: 0010:native_safe_halt+0xe/0x10 [ 66.713140][ 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 [ 66.734928][ C0] RSP: 0018:ffffffff89807d98 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 [ 66.743317][ C0] RAX: 1ffffffff132930f RBX: ffffffff898864c0 RCX: 0000000000000000 [ 66.751400][ C0] RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffffffff89886d84 [ 66.759480][ C0] RBP: dffffc0000000000 R08: ffffffff898864c0 R09: 0000000000000000 [ 66.767537][ C0] R10: 0000000000000000 R11: 0000000000000000 R12: fffffbfff1310c98 [ 66.775597][ C0] R13: 0000000000000000 R14: ffffffff8a890cc0 R15: 0000000000000000 [ 66.783658][ C0] default_idle+0x49/0x350 [ 66.788159][ C0] do_idle+0x393/0x690 [ 66.792221][ C0] ? rcu_read_lock_held+0x9c/0xb0 [ 66.797239][ C0] ? arch_cpu_idle_exit+0x70/0x70 [ 66.802263][ C0] ? schedule+0xe7/0x2a0 [ 66.806511][ C0] ? trace_init_perf_perm_irq_work_exit+0xe/0xe [ 66.812844][ C0] cpu_startup_entry+0x14/0x20 [ 66.817594][ C0] start_kernel+0x867/0x8a1 [ 66.822958][ C0] ? mem_encrypt_init+0x5/0x5 [ 66.827630][ C0] ? x86_family+0x3d/0x50 [ 66.831935][ C0] ? load_ucode_bsp+0x23d/0x27d [ 66.836986][ C0] secondary_startup_64+0xa4/0xb0