[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 55.096229][ T26] audit: type=1800 audit(1567274096.511:25): pid=8501 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 55.139409][ T26] audit: type=1800 audit(1567274096.511:26): pid=8501 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 55.185423][ T26] audit: type=1800 audit(1567274096.511:27): pid=8501 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.233' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 67.399452][ C1] [ 67.402120][ C1] ======================================================== [ 67.409304][ C1] WARNING: possible irq lock inversion dependency detected [ 67.416489][ C1] 5.3.0-rc6-next-20190827 #74 Not tainted [ 67.422179][ C1] -------------------------------------------------------- [ 67.429472][ C1] swapper/1/0 just changed the state of lock: [ 67.435743][ C1] ffff8880a5b3bb58 (&(&ctx->ctx_lock)->rlock){..-.}, at: free_ioctx_users+0x2d/0x490 [ 67.445300][ C1] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 67.453014][ C1] (&fiq->waitq){+.+.} [ 67.453023][ C1] [ 67.453023][ C1] [ 67.453023][ C1] and interrupts could create inverse lock ordering between them. [ 67.453023][ C1] [ 67.471689][ C1] [ 67.471689][ C1] other info that might help us debug this: [ 67.479791][ C1] Possible interrupt unsafe locking scenario: [ 67.479791][ C1] [ 67.488542][ C1] CPU0 CPU1 [ 67.494002][ C1] ---- ---- [ 67.499520][ C1] lock(&fiq->waitq); [ 67.503575][ C1] local_irq_disable(); [ 67.510415][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 67.518146][ C1] lock(&fiq->waitq); [ 67.524859][ C1] [ 67.528311][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 67.533712][ C1] [ 67.533712][ C1] *** DEADLOCK *** [ 67.533712][ C1] [ 67.541935][ C1] 2 locks held by swapper/1/0: [ 67.546724][ C1] #0: ffffffff88fa7e40 (rcu_callback){....}, at: rcu_core+0x60e/0x1560 [ 67.555057][ C1] #1: ffffffff88fa7e80 (rcu_read_lock_sched){....}, at: percpu_ref_switch_to_atomic_rcu+0x20e/0x570 [ 67.565902][ C1] [ 67.565902][ C1] the shortest dependencies between 2nd lock and 1st lock: [ 67.575413][ C1] -> (&fiq->waitq){+.+.} { [ 67.579902][ C1] HARDIRQ-ON-W at: [ 67.583969][ C1] lock_acquire+0x190/0x410 [ 67.590292][ C1] _raw_spin_lock+0x2f/0x40 [ 67.596760][ C1] flush_bg_queue+0x1f3/0x3c0 [ 67.603361][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 67.611265][ C1] fuse_request_send_background+0x58/0x110 [ 67.618990][ C1] cuse_channel_open+0x5ba/0x830 [ 67.625922][ C1] misc_open+0x395/0x4c0 [ 67.632185][ C1] chrdev_open+0x245/0x6b0 [ 67.638506][ C1] do_dentry_open+0x4df/0x1250 [ 67.645099][ C1] vfs_open+0xa0/0xd0 [ 67.651332][ C1] path_openat+0x10e9/0x46d0 [ 67.657741][ C1] do_filp_open+0x1a1/0x280 [ 67.664205][ C1] do_sys_open+0x3fe/0x5d0 [ 67.670495][ C1] __x64_sys_openat+0x9d/0x100 [ 67.677078][ C1] do_syscall_64+0xfa/0x760 [ 67.683483][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 67.691390][ C1] SOFTIRQ-ON-W at: [ 67.695535][ C1] lock_acquire+0x190/0x410 [ 67.701858][ C1] _raw_spin_lock+0x2f/0x40 [ 67.708512][ C1] flush_bg_queue+0x1f3/0x3c0 [ 67.715090][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 67.722887][ C1] fuse_request_send_background+0x58/0x110 [ 67.730580][ C1] cuse_channel_open+0x5ba/0x830 [ 67.737338][ C1] misc_open+0x395/0x4c0 [ 67.743405][ C1] chrdev_open+0x245/0x6b0 [ 67.749859][ C1] do_dentry_open+0x4df/0x1250 [ 67.756509][ C1] vfs_open+0xa0/0xd0 [ 67.762323][ C1] path_openat+0x10e9/0x46d0 [ 67.769057][ C1] do_filp_open+0x1a1/0x280 [ 67.775365][ C1] do_sys_open+0x3fe/0x5d0 [ 67.781817][ C1] __x64_sys_openat+0x9d/0x100 [ 67.788397][ C1] do_syscall_64+0xfa/0x760 [ 67.794785][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 67.802752][ C1] INITIAL USE at: [ 67.806907][ C1] lock_acquire+0x190/0x410 [ 67.813134][ C1] _raw_spin_lock+0x2f/0x40 [ 67.819363][ C1] flush_bg_queue+0x1f3/0x3c0 [ 67.825881][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 67.833588][ C1] fuse_request_send_background+0x58/0x110 [ 67.841341][ C1] cuse_channel_open+0x5ba/0x830 [ 67.848024][ C1] misc_open+0x395/0x4c0 [ 67.853986][ C1] chrdev_open+0x245/0x6b0 [ 67.860119][ C1] do_dentry_open+0x4df/0x1250 [ 67.866730][ C1] vfs_open+0xa0/0xd0 [ 67.872493][ C1] path_openat+0x10e9/0x46d0 [ 67.878806][ C1] do_filp_open+0x1a1/0x280 [ 67.885190][ C1] do_sys_open+0x3fe/0x5d0 [ 67.891389][ C1] __x64_sys_openat+0x9d/0x100 [ 67.900003][ C1] do_syscall_64+0xfa/0x760 [ 67.906513][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 67.914252][ C1] } [ 67.916832][ C1] ... key at: [] __key.45870+0x0/0x40 [ 67.924447][ C1] ... acquired at: [ 67.928340][ C1] _raw_spin_lock+0x2f/0x40 [ 67.933062][ C1] io_submit_one+0xefa/0x2ef0 [ 67.937903][ C1] __x64_sys_io_submit+0x1bd/0x570 [ 67.943167][ C1] do_syscall_64+0xfa/0x760 [ 67.947839][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 67.954239][ C1] [ 67.956544][ C1] -> (&(&ctx->ctx_lock)->rlock){..-.} { [ 67.962274][ C1] IN-SOFTIRQ-W at: [ 67.966441][ C1] lock_acquire+0x190/0x410 [ 67.972578][ C1] _raw_spin_lock_irq+0x60/0x80 [ 67.979078][ C1] free_ioctx_users+0x2d/0x490 [ 67.986464][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 67.994457][ C1] rcu_core+0x581/0x1560 [ 68.000343][ C1] rcu_core_si+0x9/0x10 [ 68.006213][ C1] __do_softirq+0x262/0x98c [ 68.012469][ C1] irq_exit+0x19b/0x1e0 [ 68.018261][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 68.025559][ C1] apic_timer_interrupt+0xf/0x20 [ 68.032149][ C1] native_safe_halt+0xe/0x10 [ 68.038432][ C1] default_enter_idle+0x71/0xf0 [ 68.044938][ C1] cpuidle_enter_state+0xef/0xfb0 [ 68.052070][ C1] cpuidle_enter+0x4f/0xa0 [ 68.058127][ C1] do_idle+0x45f/0x6e0 [ 68.063951][ C1] cpu_startup_entry+0x1b/0x20 [ 68.070519][ C1] start_secondary+0x2f4/0x410 [ 68.076924][ C1] secondary_startup_64+0xa4/0xb0 [ 68.083699][ C1] INITIAL USE at: [ 68.087587][ C1] lock_acquire+0x190/0x410 [ 68.093650][ C1] _raw_spin_lock_irq+0x60/0x80 [ 68.100052][ C1] io_submit_one+0xeb5/0x2ef0 [ 68.106371][ C1] __x64_sys_io_submit+0x1bd/0x570 [ 68.113044][ C1] do_syscall_64+0xfa/0x760 [ 68.119205][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 68.126643][ C1] } [ 68.129148][ C1] ... key at: [] __key.54388+0x0/0x40 [ 68.136590][ C1] ... acquired at: [ 68.140391][ C1] mark_lock+0x517/0x1220 [ 68.144893][ C1] __lock_acquire+0x1e8e/0x4a00 [ 68.150079][ C1] lock_acquire+0x190/0x410 [ 68.154758][ C1] _raw_spin_lock_irq+0x60/0x80 [ 68.159762][ C1] free_ioctx_users+0x2d/0x490 [ 68.164679][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 68.170981][ C1] rcu_core+0x581/0x1560 [ 68.175379][ C1] rcu_core_si+0x9/0x10 [ 68.179752][ C1] __do_softirq+0x262/0x98c [ 68.184488][ C1] irq_exit+0x19b/0x1e0 [ 68.188917][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 68.194632][ C1] apic_timer_interrupt+0xf/0x20 [ 68.199824][ C1] native_safe_halt+0xe/0x10 [ 68.204632][ C1] default_enter_idle+0x71/0xf0 [ 68.209646][ C1] cpuidle_enter_state+0xef/0xfb0 [ 68.215003][ C1] cpuidle_enter+0x4f/0xa0 [ 68.219589][ C1] do_idle+0x45f/0x6e0 [ 68.223910][ C1] cpu_startup_entry+0x1b/0x20 [ 68.228837][ C1] start_secondary+0x2f4/0x410 [ 68.233896][ C1] secondary_startup_64+0xa4/0xb0 [ 68.239072][ C1] [ 68.241531][ C1] [ 68.241531][ C1] stack backtrace: [ 68.247515][ C1] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.3.0-rc6-next-20190827 #74 [ 68.255818][ C1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 68.266089][ C1] Call Trace: [ 68.269357][ C1] [ 68.272200][ C1] dump_stack+0x172/0x1f0 [ 68.276512][ C1] print_irq_inversion_bug.part.0+0x2e4/0x2f1 [ 68.282734][ C1] check_usage_forwards.cold+0x20/0x29 [ 68.288289][ C1] ? check_usage_backwards+0x330/0x330 [ 68.293736][ C1] ? save_trace+0x3e/0x8c0 [ 68.298131][ C1] mark_lock+0x517/0x1220 [ 68.302761][ C1] ? check_usage_backwards+0x330/0x330 [ 68.308224][ C1] __lock_acquire+0x1e8e/0x4a00 [ 68.313124][ C1] ? __kasan_check_read+0x11/0x20 [ 68.318140][ C1] ? mark_lock+0xc2/0x1220 [ 68.322539][ C1] ? mark_held_locks+0xf0/0xf0 [ 68.327421][ C1] lock_acquire+0x190/0x410 [ 68.332091][ C1] ? free_ioctx_users+0x2d/0x490 [ 68.337029][ C1] _raw_spin_lock_irq+0x60/0x80 [ 68.341882][ C1] ? free_ioctx_users+0x2d/0x490 [ 68.346805][ C1] free_ioctx_users+0x2d/0x490 [ 68.351578][ C1] ? rcu_dynticks_curr_cpu_in_eqs+0x54/0xb0 [ 68.357475][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 68.363625][ C1] ? percpu_ref_exit+0xd0/0xd0 [ 68.368417][ C1] rcu_core+0x581/0x1560 [ 68.372796][ C1] ? __rcu_read_unlock+0x6b0/0x6b0 [ 68.377951][ C1] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 68.383738][ C1] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 68.389723][ C1] ? run_rebalance_domains+0x227/0x2d0 [ 68.395298][ C1] rcu_core_si+0x9/0x10 [ 68.399725][ C1] __do_softirq+0x262/0x98c [ 68.404208][ C1] ? sched_clock_cpu+0x1b/0x1b0 [ 68.409173][ C1] irq_exit+0x19b/0x1e0 [ 68.413492][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 68.419032][ C1] apic_timer_interrupt+0xf/0x20 [ 68.424070][ C1] [ 68.427009][ C1] RIP: 0010:native_safe_halt+0xe/0x10 [ 68.432623][ C1] Code: 78 26 6a fa eb 8a 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d 04 3e 65 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d f4 3d 65 00 fb f4 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 e8 2e 07 1d fa e8 29 [ 68.452708][ C1] RSP: 0018:ffff8880a98dfcd0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 [ 68.461257][ C1] RAX: 1ffffffff11e5daf RBX: 0000000000000000 RCX: 0000000000000000 [ 68.469485][ C1] RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880a98ccbdc [ 68.477610][ C1] RBP: ffff8880a98dfd00 R08: ffff8880a98cc340 R09: 0000000000000000 [ 68.485562][ C1] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 [ 68.493635][ C1] R13: 0000000000000000 R14: 0000000000000060 R15: 0000000000000001 [ 68.501729][ C1] ? default_idle+0x4e/0x360 [ 68.506540][ C1] default_enter_idle+0x71/0xf0 [ 68.511383][ C1] cpuidle_enter_state+0xef/0xfb0 [ 68.516404][ C1] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 68.524571][ C1] cpuidle_enter+0x4f/0xa0 [ 68.529207][ C1] do_idle+0x45f/0x6e0 [ 68.533469][ C1] ? arch_cpu_idle_exit+0x80/0x80 [ 68.538854][ C1] ? _raw_read_unlock_irqrestore+0xc0/0xe0 [ 68.544824][ C1] ? complete+0x61/0x80 [ 68.548986][ C1] cpu_startup_entry+0x1b/0x20 [ 68.