[ OK ] Started Getty on tty2. Starting Load/Save RF Kill Switch Status... [ 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 Load/Save RF Kill Switch Status. [ OK ] Started Update UTMP about System Runlevel Changes. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.160' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 60.315257][ C1] [ 60.317617][ C1] ======================================================== [ 60.324790][ C1] WARNING: possible irq lock inversion dependency detected [ 60.331972][ C1] 5.6.0-syzkaller #0 Not tainted [ 60.336888][ C1] -------------------------------------------------------- [ 60.344070][ C1] swapper/1/0 just changed the state of lock: [ 60.350137][ C1] ffff88808fabbcd8 (&ctx->ctx_lock){..-.}-{2:2}, at: free_ioctx_users+0x2b/0x450 [ 60.359281][ C1] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 60.366805][ C1] (&pid->wait_pidfd){+.+.}-{2:2} [ 60.366815][ C1] [ 60.366815][ C1] [ 60.366815][ C1] and interrupts could create inverse lock ordering between them. [ 60.366815][ C1] [ 60.386204][ C1] [ 60.386204][ C1] other info that might help us debug this: [ 60.394249][ C1] Possible interrupt unsafe locking scenario: [ 60.394249][ C1] [ 60.402568][ C1] CPU0 CPU1 [ 60.407918][ C1] ---- ---- [ 60.413261][ C1] lock(&pid->wait_pidfd); [ 60.417742][ C1] local_irq_disable(); [ 60.424481][ C1] lock(&ctx->ctx_lock); [ 60.431310][ C1] lock(&pid->wait_pidfd); [ 60.438324][ C1] [ 60.441759][ C1] lock(&ctx->ctx_lock); [ 60.446242][ C1] [ 60.446242][ C1] *** DEADLOCK *** [ 60.446242][ C1] [ 60.454375][ C1] 2 locks held by swapper/1/0: [ 60.459119][ C1] #0: ffffffff899bc060 (rcu_callback){....}-{0:0}, at: rcu_core+0x520/0x1370 [ 60.467966][ C1] #1: ffffffff899bc180 (rcu_read_lock){....}-{1:2}, at: percpu_ref_switch_to_atomic_rcu+0x209/0x540 [ 60.478812][ C1] [ 60.478812][ C1] the shortest dependencies between 2nd lock and 1st lock: [ 60.488190][ C1] -> (&pid->wait_pidfd){+.+.}-{2:2} { [ 60.493647][ C1] HARDIRQ-ON-W at: [ 60.497722][ C1] lock_acquire+0x1f2/0x8f0 [ 60.504033][ C1] _raw_spin_lock+0x2a/0x40 [ 60.510361][ C1] proc_pid_make_inode+0x1f9/0x3c0 [ 60.517295][ C1] proc_pid_instantiate+0x51/0x150 [ 60.524224][ C1] proc_pid_lookup+0x1da/0x340 [ 60.531019][ C1] proc_root_lookup+0x20/0x60 [ 60.537505][ C1] __lookup_slow+0x256/0x490 [ 60.543903][ C1] walk_component+0x418/0x6a0 [ 60.550391][ C1] link_path_walk.part.0+0x4f1/0xb50 [ 60.557484][ C1] path_openat+0x25a/0x27d0 [ 60.563791][ C1] do_filp_open+0x192/0x260 [ 60.570113][ C1] do_sys_openat2+0x585/0x7d0 [ 60.576612][ C1] do_sys_open+0xc3/0x140 [ 60.582764][ C1] do_syscall_64+0xf6/0x7d0 [ 60.589076][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 60.596769][ C1] SOFTIRQ-ON-W at: [ 60.600831][ C1] lock_acquire+0x1f2/0x8f0 [ 60.607145][ C1] _raw_spin_lock+0x2a/0x40 [ 60.613511][ C1] proc_pid_make_inode+0x1f9/0x3c0 [ 60.620434][ C1] proc_pid_instantiate+0x51/0x150 [ 60.627389][ C1] proc_pid_lookup+0x1da/0x340 [ 60.633998][ C1] proc_root_lookup+0x20/0x60 [ 60.640623][ C1] __lookup_slow+0x256/0x490 [ 60.647020][ C1] walk_component+0x418/0x6a0 [ 60.653502][ C1] link_path_walk.part.0+0x4f1/0xb50 [ 60.660682][ C1] path_openat+0x25a/0x27d0 [ 60.666992][ C1] do_filp_open+0x192/0x260 [ 60.673314][ C1] do_sys_openat2+0x585/0x7d0 [ 60.679806][ C1] do_sys_open+0xc3/0x140 [ 60.686034][ C1] do_syscall_64+0xf6/0x7d0 [ 60.692371][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 60.700065][ C1] INITIAL USE at: [ 60.704034][ C1] lock_acquire+0x1f2/0x8f0 [ 60.710267][ C1] _raw_spin_lock_irqsave+0x8c/0xbf [ 60.717187][ C1] __wake_up_common_lock+0xb4/0x130 [ 60.724106][ C1] do_notify_parent+0x19e/0xe60 [ 60.730693][ C1] do_exit+0x238f/0x2dd0 [ 60.736675][ C1] call_usermodehelper_exec_async+0x507/0x710 [ 60.744462][ C1] ret_from_fork+0x24/0x30 [ 60.750593][ C1] } [ 60.753166][ C1] ... key at: [] __key.53831+0x0/0x40 [ 60.760685][ C1] ... acquired at: [ 60.764562][ C1] _raw_spin_lock+0x2a/0x40 [ 60.769219][ C1] io_submit_one+0xc1b/0x2ec0 [ 60.774072][ C1] __ia32_compat_sys_io_submit+0x1bf/0x530 [ 60.780037][ C1] do_fast_syscall_32+0x270/0xe90 [ 60.785238][ C1] entry_SYSENTER_compat+0x70/0x7f [ 60.790496][ C1] [ 60.792800][ C1] -> (&ctx->ctx_lock){..-.}-{2:2} { [ 60.797981][ C1] IN-SOFTIRQ-W at: [ 60.801948][ C1] lock_acquire+0x1f2/0x8f0 [ 60.808087][ C1] _raw_spin_lock_irq+0x5b/0x80 [ 60.814584][ C1] free_ioctx_users+0x2b/0x450 [ 60.820994][ C1] percpu_ref_switch_to_atomic_rcu+0x494/0x540 [ 60.828785][ C1] rcu_core+0x59f/0x1370 [ 60.834662][ C1] __do_softirq+0x26c/0x9f7 [ 60.840813][ C1] irq_exit+0x192/0x1d0 [ 60.846631][ C1] smp_apic_timer_interrupt+0x19e/0x600 [ 60.853818][ C1] apic_timer_interrupt+0xf/0x20 [ 60.860391][ C1] native_safe_halt+0xe/0x10 [ 60.866616][ C1] default_idle+0x49/0x350 [ 60.872860][ C1] do_idle+0x393/0x690 [ 60.878573][ C1] cpu_startup_entry+0x14/0x20 [ 60.884984][ C1] start_secondary+0x2f3/0x400 [ 60.891423][ C1] secondary_startup_64+0xa4/0xb0 [ 60.898094][ C1] INITIAL USE at: [ 60.901990][ C1] lock_acquire+0x1f2/0x8f0 [ 60.908040][ C1] _raw_spin_lock_irq+0x5b/0x80 [ 60.914447][ C1] io_submit_one+0xbd6/0x2ec0 [ 60.920675][ C1] __ia32_compat_sys_io_submit+0x1bf/0x530 [ 60.928111][ C1] do_fast_syscall_32+0x270/0xe90 [ 60.934702][ C1] entry_SYSENTER_compat+0x70/0x7f [ 60.941358][ C1] } [ 60.943847][ C1] ... key at: [] __key.55314+0x0/0x40 [ 60.951284][ C1] ... acquired at: [ 60.955081][ C1] mark_lock+0x624/0xf10 [ 60.959490][ C1] __lock_acquire+0x1d28/0x4e00 [ 60.964621][ C1] lock_acquire+0x1f2/0x8f0 [ 60.969283][ C1] _raw_spin_lock_irq+0x5b/0x80 [ 60.974300][ C1] free_ioctx_users+0x2b/0x450 [ 60.979228][ C1] percpu_ref_switch_to_atomic_rcu+0x494/0x540 [ 60.985550][ C1] rcu_core+0x59f/0x1370 [ 60.989953][ C1] __do_softirq+0x26c/0x9f7 [ 60.994609][ C1] irq_exit+0x192/0x1d0 [ 60.998921][ C1] smp_apic_timer_interrupt+0x19e/0x600 [ 61.004638][ C1] apic_timer_interrupt+0xf/0x20 [ 61.009733][ C1] native_safe_halt+0xe/0x10 [ 61.014478][ C1] default_idle+0x49/0x350 [ 61.019059][ C1] do_idle+0x393/0x690 [ 61.023280][ C1] cpu_startup_entry+0x14/0x20 [ 61.028216][ C1] start_secondary+0x2f3/0x400 [ 61.033148][ C1] secondary_startup_64+0xa4/0xb0 [ 61.038318][ C1] [ 61.040620][ C1] [ 61.040620][ C1] stack backtrace: [ 61.046493][ C1] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.6.0-syzkaller #0 [ 61.054014][ C1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 61.064098][ C1] Call Trace: [ 61.067393][ C1] [ 61.070266][ C1] dump_stack+0x188/0x20d [ 61.074579][ C1] check_usage_forwards.cold+0x20/0x29 [ 61.080071][ C1] ? check_usage_backwards+0x4e0/0x4e0 [ 61.085515][ C1] ? stack_trace_consume_entry+0x160/0x160 [ 61.091316][ C1] ? __read_once_size_nocheck.constprop.0+0x10/0x10 [ 61.097890][ C1] ? get_stack_info+0x32/0x13e [ 61.102680][ C1] ? save_trace+0x42/0x9f0 [ 61.107131][ C1] mark_lock+0x624/0xf10 [ 61.111365][ C1] ? check_usage_backwards+0x4e0/0x4e0 [ 61.116816][ C1] ? print_usage_bug+0x240/0x240 [ 61.121740][ C1] ? print_usage_bug+0x240/0x240 [ 61.126686][ C1] ? mark_lock+0x12b/0xf10 [ 61.131089][ C1] __lock_acquire+0x1d28/0x4e00 [ 61.135945][ C1] ? mark_held_locks+0xe0/0xe0 [ 61.140691][ C1] ? __wake_up_common_lock+0xde/0x130 [ 61.146056][ C1] lock_acquire+0x1f2/0x8f0 [ 61.150567][ C1] ? free_ioctx_users+0x2b/0x450 [ 61.155493][ C1] ? lock_release+0x800/0x800 [ 61.160164][ C1] ? lock_acquire+0x1f2/0x8f0 [ 61.164838][ C1] ? percpu_ref_switch_to_atomic_rcu+0x209/0x540 [ 61.171246][ C1] ? lock_release+0x800/0x800 [ 61.176010][ C1] ? _raw_spin_unlock_irqrestore+0x62/0xe0 [ 61.181920][ C1] _raw_spin_lock_irq+0x5b/0x80 [ 61.186764][ C1] ? free_ioctx_users+0x2b/0x450 [ 61.191692][ C1] free_ioctx_users+0x2b/0x450 [ 61.196494][ C1] percpu_ref_switch_to_atomic_rcu+0x494/0x540 [ 61.202658][ C1] rcu_core+0x59f/0x1370 [ 61.206883][ C1] ? __rcu_read_unlock+0x700/0x700 [ 61.211977][ C1] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 61.217538][ C1] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 61.223512][ C1] ? run_rebalance_domains+0x202/0x2c0 [ 61.228956][ C1] __do_softirq+0x26c/0x9f7 [ 61.233443][ C1] irq_exit+0x192/0x1d0 [ 61.237585][ C1] smp_apic_timer_interrupt+0x19e/0x600 [ 61.243116][ C1] apic_timer_interrupt+0xf/0x20 [ 61.248045][ C1] [ 61.250966][ C1] RIP: 0010:native_safe_halt+0xe/0x10 [ 61.256325][ C1] 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 [ 61.276036][ C1] RSP: 0018:ffffc90000d3fdb8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 [ 61.284436][ C1] RAX: 1ffffffff132930f RBX: ffff8880a95f2340 RCX: 0000000000000000 [ 61.292403][ C1] RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880a95f2c04 [ 61.300375][ C1] RBP: dffffc0000000000 R08: ffff8880a95f2340 R09: 0000000000000000 [ 61.308349][ C1] R10: 0000000000000000 R11: 0000000000000000 R12: ffffed10152be468 [ 61.316322][ C1] R13: 000000000000