Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.15.203' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 61.347562][ C0] [ 61.350037][ C0] ======================================================== [ 61.357239][ C0] WARNING: possible irq lock inversion dependency detected [ 61.364434][ C0] 5.6.0-syzkaller #0 Not tainted [ 61.369363][ C0] -------------------------------------------------------- [ 61.377164][ C0] swapper/0/0 just changed the state of lock: [ 61.383225][ C0] ffff888095689cd8 (&ctx->ctx_lock){..-.}-{2:2}, at: free_ioctx_users+0x2b/0x450 [ 61.392351][ C0] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 61.399994][ C0] (&pid->wait_pidfd){+.+.}-{2:2} [ 61.400012][ C0] [ 61.400012][ C0] [ 61.400012][ C0] and interrupts could create inverse lock ordering between them. [ 61.400012][ C0] [ 61.419327][ C0] [ 61.419327][ C0] other info that might help us debug this: [ 61.427367][ C0] Possible interrupt unsafe locking scenario: [ 61.427367][ C0] [ 61.435673][ C0] CPU0 CPU1 [ 61.443273][ C0] ---- ---- [ 61.448628][ C0] lock(&pid->wait_pidfd); [ 61.453106][ C0] local_irq_disable(); [ 61.459837][ C0] lock(&ctx->ctx_lock); [ 61.466672][ C0] lock(&pid->wait_pidfd); [ 61.473666][ C0] [ 61.477113][ C0] lock(&ctx->ctx_lock); [ 61.481726][ C0] [ 61.481726][ C0] *** DEADLOCK *** [ 61.481726][ C0] [ 61.489861][ C0] 2 locks held by swapper/0/0: [ 61.494602][ C0] #0: ffffffff899bc060 (rcu_callback){....}-{0:0}, at: rcu_core+0x520/0x1370 [ 61.503456][ C0] #1: ffffffff899bc180 (rcu_read_lock){....}-{1:2}, at: percpu_ref_switch_to_atomic_rcu+0x209/0x540 [ 61.514298][ C0] [ 61.514298][ C0] the shortest dependencies between 2nd lock and 1st lock: [ 61.523654][ C0] -> (&pid->wait_pidfd){+.+.}-{2:2} { [ 61.529105][ C0] HARDIRQ-ON-W at: [ 61.533169][ C0] lock_acquire+0x1f2/0x8f0 [ 61.539487][ C0] _raw_spin_lock+0x2a/0x40 [ 61.545791][ C0] proc_pid_make_inode+0x1f9/0x3c0 [ 61.552702][ C0] proc_pid_instantiate+0x51/0x150 [ 61.559612][ C0] proc_pid_lookup+0x1da/0x340 [ 61.566189][ C0] proc_root_lookup+0x20/0x60 [ 61.572699][ C0] __lookup_slow+0x256/0x490 [ 61.579136][ C0] walk_component+0x418/0x6a0 [ 61.585627][ C0] link_path_walk.part.0+0x4f1/0xb50 [ 61.592723][ C0] path_openat+0x25a/0x27d0 [ 61.599045][ C0] do_filp_open+0x192/0x260 [ 61.605347][ C0] do_sys_openat2+0x585/0x7d0 [ 61.611824][ C0] do_sys_open+0xc3/0x140 [ 61.617972][ C0] do_syscall_64+0xf6/0x7d0 [ 61.624318][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 61.632140][ C0] SOFTIRQ-ON-W at: [ 61.636214][ C0] lock_acquire+0x1f2/0x8f0 [ 61.642525][ C0] _raw_spin_lock+0x2a/0x40 [ 61.648849][ C0] proc_pid_make_inode+0x1f9/0x3c0 [ 61.655790][ C0] proc_pid_instantiate+0x51/0x150 [ 61.662701][ C0] proc_pid_lookup+0x1da/0x340 [ 61.669275][ C0] proc_root_lookup+0x20/0x60 [ 61.675763][ C0] __lookup_slow+0x256/0x490 [ 61.682165][ C0] walk_component+0x418/0x6a0 [ 61.688827][ C0] link_path_walk.part.0+0x4f1/0xb50 [ 61.696008][ C0] path_openat+0x25a/0x27d0 [ 61.702328][ C0] do_filp_open+0x192/0x260 [ 61.708634][ C0] do_sys_openat2+0x585/0x7d0 [ 61.715117][ C0] do_sys_open+0xc3/0x140 [ 61.721263][ C0] do_syscall_64+0xf6/0x7d0 [ 61.727607][ C0] entry_SYSCALL_64_after_hwframe+0x49/0xb3 [ 61.735309][ C0] INITIAL USE at: [ 61.739402][ C0] lock_acquire+0x1f2/0x8f0 [ 61.745753][ C0] _raw_spin_lock_irqsave+0x8c/0xbf [ 61.752693][ C0] __wake_up_common_lock+0xb4/0x130 [ 61.759613][ C0] do_notify_parent+0x19e/0xe60 [ 61.766203][ C0] do_exit+0x238f/0x2dd0 [ 61.772175][ C0] call_usermodehelper_exec_async+0x507/0x710 [ 61.780040][ C0] ret_from_fork+0x24/0x30 [ 61.786474][ C0] } [ 61.789064][ C0] ... key at: [] __key.53831+0x0/0x40 [ 61.796618][ C0] ... acquired at: [ 61.800502][ C0] _raw_spin_lock+0x2a/0x40 [ 61.805439][ C0] io_submit_one+0xc1b/0x2ec0 [ 61.810529][ C0] __ia32_compat_sys_io_submit+0x1bf/0x530 [ 61.816587][ C0] do_fast_syscall_32+0x270/0xe90 [ 61.821763][ C0] entry_SYSENTER_compat+0x70/0x7f [ 61.827020][ C0] [ 61.829323][ C0] -> (&ctx->ctx_lock){..-.}-{2:2} { [ 61.834686][ C0] IN-SOFTIRQ-W at: [ 61.838649][ C0] lock_acquire+0x1f2/0x8f0 [ 61.844776][ C0] _raw_spin_lock_irq+0x5b/0x80 [ 61.851253][ C0] free_ioctx_users+0x2b/0x450 [ 61.857660][ C0] percpu_ref_switch_to_atomic_rcu+0x494/0x540 [ 61.865611][ C0] rcu_core+0x59f/0x1370 [ 61.871497][ C0] __do_softirq+0x26c/0x9f7 [ 61.877656][ C0] irq_exit+0x192/0x1d0 [ 61.883461][ C0] smp_apic_timer_interrupt+0x19e/0x600 [ 61.890640][ C0] apic_timer_interrupt+0xf/0x20 [ 61.897207][ C0] native_safe_halt+0xe/0x10 [ 61.903432][ C0] default_idle+0x49/0x350 [ 61.909492][ C0] do_idle+0x393/0x690 [ 61.915185][ C0] cpu_startup_entry+0x14/0x20 [ 61.921595][ C0] start_kernel+0x867/0x8a1 [ 61.927748][ C0] secondary_startup_64+0xa4/0xb0 [ 61.934406][ C0] INITIAL USE at: [ 61.938298][ C0] lock_acquire+0x1f2/0x8f0 [ 61.945307][ C0] _raw_spin_lock_irq+0x5b/0x80 [ 61.951710][ C0] io_submit_one+0xbd6/0x2ec0 [ 61.957926][ C0] __ia32_compat_sys_io_submit+0x1bf/0x530 [ 61.965297][ C0] do_fast_syscall_32+0x270/0xe90 [ 61.971926][ C0] entry_SYSENTER_compat+0x70/0x7f [ 61.978592][ C0] } [ 61.981082][ C0] ... key at: [] __key.55314+0x0/0x40 [ 61.988642][ C0] ... acquired at: [ 61.992488][ C0] mark_lock+0x624/0xf10 [ 61.996910][ C0] __lock_acquire+0x1d28/0x4e00 [ 62.001942][ C0] lock_acquire+0x1f2/0x8f0 [ 62.006599][ C0] _raw_spin_lock_irq+0x5b/0x80 [ 62.011604][ C0] free_ioctx_users+0x2b/0x450 [ 62.016536][ C0] percpu_ref_switch_to_atomic_rcu+0x494/0x540 [ 62.022839][ C0] rcu_core+0x59f/0x1370 [ 62.027317][ C0] __do_softirq+0x26c/0x9f7 [ 62.031970][ C0] irq_exit+0x192/0x1d0 [ 62.036276][ C0] smp_apic_timer_interrupt+0x19e/0x600 [ 62.041986][ C0] apic_timer_interrupt+0xf/0x20 [ 62.047083][ C0] native_safe_halt+0xe/0x10 [ 62.051958][ C0] default_idle+0x49/0x350 [ 62.056545][ C0] do_idle+0x393/0x690 [ 62.060768][ C0] cpu_startup_entry+0x14/0x20 [ 62.065715][ C0] start_kernel+0x867/0x8a1 [ 62.070386][ C0] secondary_startup_64+0xa4/0xb0 [ 62.075556][ C0] [ 62.077874][ C0] [ 62.077874][ C0] stack backtrace: [ 62.083776][ C0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-syzkaller #0 [ 62.091317][ C0] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 62.101360][ C0] Call Trace: [ 62.104631][ C0] [ 62.107469][ C0] dump_stack+0x188/0x20d [ 62.111782][ C0] check_usage_forwards.cold+0x20/0x29 [ 62.117260][ C0] ? check_usage_backwards+0x4e0/0x4e0 [ 62.122739][ C0] ? stack_trace_consume_entry+0x160/0x160 [ 62.128576][ C0] ? __read_once_size_nocheck.constprop.0+0x10/0x10 [ 62.135293][ C0] ? save_trace+0x42/0x9f0 [ 62.139817][ C0] mark_lock+0x624/0xf10 [ 62.144047][ C0] ? check_usage_backwards+0x4e0/0x4e0 [ 62.149503][ C0] ? print_usage_bug+0x240/0x240 [ 62.154463][ C0] ? print_usage_bug+0x240/0x240 [ 62.159438][ C0] ? mark_lock+0x12b/0xf10 [ 62.163843][ C0] __lock_acquire+0x1d28/0x4e00 [ 62.168684][ C0] ? mark_held_locks+0xe0/0xe0 [ 62.173506][ C0] ? __wake_up_common_lock+0xde/0x130 [ 62.178922][ C0] lock_acquire+0x1f2/0x8f0 [ 62.183524][ C0] ? free_ioctx_users+0x2b/0x450 [ 62.188773][ C0] ? lock_release+0x800/0x800 [ 62.193438][ C0] ? lock_acquire+0x1f2/0x8f0 [ 62.198370][ C0] ? percpu_ref_switch_to_atomic_rcu+0x209/0x540 [ 62.204709][ C0] ? lock_release+0x800/0x800 [ 62.209377][ C0] ? _raw_spin_unlock_irqrestore+0x62/0xe0 [ 62.215263][ C0] _raw_spin_lock_irq+0x5b/0x80 [ 62.220097][ C0] ? free_ioctx_users+0x2b/0x450 [ 62.225023][ C0] free_ioctx_users+0x2b/0x450 [ 62.229862][ C0] percpu_ref_switch_to_atomic_rcu+0x494/0x540 [ 62.236026][ C0] rcu_core+0x59f/0x1370 [ 62.240251][ C0] ? __rcu_read_unlock+0x700/0x700 [ 62.245375][ C0] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 62.250904][ C0] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 62.256889][ C0] ? run_rebalance_domains+0x202/0x2c0 [ 62.262444][ C0] __do_softirq+0x26c/0x9f7 [ 62.267000][ C0] irq_exit+0x192/0x1d0 [ 62.271146][ C0] smp_apic_timer_interrupt+0x19e/0x600 [ 62.276670][ C0] apic_timer_interrupt+0xf/0x20 [ 62.281581][ C0] [ 62.284516][ C0] RIP: 0010:native_safe_halt+0xe/0x10 [ 62.289887][ 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 [ 62.309483][ C0] RSP: 0018:ffffffff89807d98 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13 [ 62.317902][ C0] RAX: 1ffffffff132930f RBX: ffffffff898864c0 RCX: 0000000000000000 [ 62.325915][ C0] RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffffffff89886d84 [ 62.333885][ C0] RBP: dffffc0000000000 R08: ffffffff898864c0 R09: 0000000000000000 [ 62.341855][ C0] R10: 0000000000000000 R11: 0000000000000000 R12: fffffbfff1310c98 [ 62.349821][ C0] R13: 0000000000000000 R14: ffffffff8a890cc0 R15: 0000000000000000 [ 62.357799][ C0] default_idle+0x49/0x350 [ 62.362266][ C0] do_idle+0x393/0x690 [ 62.366524][ C0] ? rcu_read_lock_held+0x9c/0xb0 [ 62.371545][ C0] ? arch_cpu_idle_exit+0x70/0x70 [ 62.376620][ C0] ? schedule+0xe7/0x2a0 [ 62.380935][ C0] ? trace_init_perf_perm_irq_work_exit+0xe/0xe [ 62.387169][ C0] cpu_startup_entry+0x14/0x20 [ 62.392099][ C0] start_kernel+0x867/0x8a1 [ 62.396670][ C0] ? mem_encrypt_init+0x5/0x5 [ 62.401339][ C0] ? x86_family+0x3d/0x50 [ 62.405782][ C0] ? load_ucode_bsp+0x23d/0x27d [ 62.410627][ C0] secondary_startup_64+0xa4/0xb0