[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 54.629783][ T26] audit: type=1800 audit(1567584631.031:25): pid=8538 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 54.651053][ T26] audit: type=1800 audit(1567584631.031:26): pid=8538 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 54.671673][ T26] audit: type=1800 audit(1567584631.031:27): pid=8538 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 '10.128.15.201' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 63.250177][ C1] [ 63.252519][ C1] ======================================================== [ 63.259877][ C1] WARNING: possible irq lock inversion dependency detected [ 63.267101][ C1] 5.3.0-rc6-next-20190830 #75 Not tainted [ 63.272789][ C1] -------------------------------------------------------- [ 63.279959][ C1] swapper/1/0 just changed the state of lock: [ 63.285997][ C1] ffff888096395b58 (&(&ctx->ctx_lock)->rlock){..-.}, at: free_ioctx_users+0x2d/0x490 [ 63.295432][ C1] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 63.302941][ C1] (&fiq->waitq){+.+.} [ 63.302947][ C1] [ 63.302947][ C1] [ 63.302947][ C1] and interrupts could create inverse lock ordering between them. [ 63.302947][ C1] [ 63.321264][ C1] [ 63.321264][ C1] other info that might help us debug this: [ 63.329295][ C1] Possible interrupt unsafe locking scenario: [ 63.329295][ C1] [ 63.337585][ C1] CPU0 CPU1 [ 63.342921][ C1] ---- ---- [ 63.348276][ C1] lock(&fiq->waitq); [ 63.352323][ C1] local_irq_disable(); [ 63.359049][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 63.367598][ C1] lock(&fiq->waitq); [ 63.374153][ C1] [ 63.377581][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 63.382920][ C1] [ 63.382920][ C1] *** DEADLOCK *** [ 63.382920][ C1] [ 63.391041][ C1] 2 locks held by swapper/1/0: [ 63.395779][ C1] #0: ffffffff88fa7e40 (rcu_callback){....}, at: rcu_core+0x60e/0x1560 [ 63.404086][ C1] #1: ffffffff88fa7e80 (rcu_read_lock_sched){....}, at: percpu_ref_switch_to_atomic_rcu+0x20e/0x570 [ 63.414909][ C1] [ 63.414909][ C1] the shortest dependencies between 2nd lock and 1st lock: [ 63.424246][ C1] -> (&fiq->waitq){+.+.} { [ 63.428719][ C1] HARDIRQ-ON-W at: [ 63.432763][ C1] lock_acquire+0x190/0x410 [ 63.439059][ C1] _raw_spin_lock+0x2f/0x40 [ 63.445357][ C1] flush_bg_queue+0x1f1/0x3b0 [ 63.451830][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 63.459602][ C1] fuse_request_send_background+0x58/0x110 [ 63.467200][ C1] cuse_channel_open+0x5c3/0x839 [ 63.473941][ C1] misc_open+0x395/0x4c0 [ 63.479980][ C1] chrdev_open+0x245/0x6b0 [ 63.486189][ C1] do_dentry_open+0x4df/0x1250 [ 63.492747][ C1] vfs_open+0xa0/0xd0 [ 63.498533][ C1] path_openat+0x10e9/0x46d0 [ 63.504919][ C1] do_filp_open+0x1a1/0x280 [ 63.511221][ C1] do_sys_open+0x3fe/0x5d0 [ 63.517431][ C1] __x64_sys_openat+0x9d/0x100 [ 63.524000][ C1] do_syscall_64+0xfa/0x760 [ 63.530300][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 63.537990][ C1] SOFTIRQ-ON-W at: [ 63.542032][ C1] lock_acquire+0x190/0x410 [ 63.548332][ C1] _raw_spin_lock+0x2f/0x40 [ 63.554653][ C1] flush_bg_queue+0x1f1/0x3b0 [ 63.561149][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 63.568939][ C1] fuse_request_send_background+0x58/0x110 [ 63.576551][ C1] cuse_channel_open+0x5c3/0x839 [ 63.583284][ C1] misc_open+0x395/0x4c0 [ 63.589344][ C1] chrdev_open+0x245/0x6b0 [ 63.595557][ C1] do_dentry_open+0x4df/0x1250 [ 63.602116][ C1] vfs_open+0xa0/0xd0 [ 63.607893][ C1] path_openat+0x10e9/0x46d0 [ 63.614276][ C1] do_filp_open+0x1a1/0x280 [ 63.620574][ C1] do_sys_open+0x3fe/0x5d0 [ 63.626796][ C1] __x64_sys_openat+0x9d/0x100 [ 63.633357][ C1] do_syscall_64+0xfa/0x760 [ 63.639675][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 63.647358][ C1] INITIAL USE at: [ 63.651318][ C1] lock_acquire+0x190/0x410 [ 63.657527][ C1] _raw_spin_lock+0x2f/0x40 [ 63.663741][ C1] flush_bg_queue+0x1f1/0x3b0 [ 63.670137][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 63.677822][ C1] fuse_request_send_background+0x58/0x110 [ 63.685690][ C1] cuse_channel_open+0x5c3/0x839 [ 63.692333][ C1] misc_open+0x395/0x4c0 [ 63.698283][ C1] chrdev_open+0x245/0x6b0 [ 63.704408][ C1] do_dentry_open+0x4df/0x1250 [ 63.710881][ C1] vfs_open+0xa0/0xd0 [ 63.716571][ C1] path_openat+0x10e9/0x46d0 [ 63.722871][ C1] do_filp_open+0x1a1/0x280 [ 63.729081][ C1] do_sys_open+0x3fe/0x5d0 [ 63.735203][ C1] __x64_sys_openat+0x9d/0x100 [ 63.741688][ C1] do_syscall_64+0xfa/0x760 [ 63.747909][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 63.755502][ C1] } [ 63.758068][ C1] ... key at: [] __key.44810+0x0/0x40 [ 63.765576][ C1] ... acquired at: [ 63.769445][ C1] _raw_spin_lock+0x2f/0x40 [ 63.774095][ C1] io_submit_one+0xefa/0x2ef0 [ 63.778929][ C1] __x64_sys_io_submit+0x1bd/0x570 [ 63.784187][ C1] do_syscall_64+0xfa/0x760 [ 63.788837][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 63.794880][ C1] [ 63.797177][ C1] -> (&(&ctx->ctx_lock)->rlock){..-.} { [ 63.802692][ C1] IN-SOFTIRQ-W at: [ 63.806648][ C1] lock_acquire+0x190/0x410 [ 63.812774][ C1] _raw_spin_lock_irq+0x60/0x80 [ 63.819246][ C1] free_ioctx_users+0x2d/0x490 [ 63.825643][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 63.833416][ C1] rcu_core+0x581/0x1560 [ 63.839289][ C1] rcu_core_si+0x9/0x10 [ 63.845083][ C1] __do_softirq+0x262/0x98c [ 63.851214][ C1] irq_exit+0x19b/0x1e0 [ 63.857002][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 63.864172][ C1] apic_timer_interrupt+0xf/0x20 [ 63.870733][ C1] native_safe_halt+0xe/0x10 [ 63.876949][ C1] default_enter_idle+0x71/0xf0 [ 63.883419][ C1] cpuidle_enter_state+0xef/0xfb0 [ 63.890077][ C1] cpuidle_enter+0x4f/0xa0 [ 63.896203][ C1] do_idle+0x45f/0x6e0 [ 63.901892][ C1] cpu_startup_entry+0x1b/0x20 [ 63.908277][ C1] start_secondary+0x2f4/0x410 [ 63.914662][ C1] secondary_startup_64+0xa4/0xb0 [ 63.921303][ C1] INITIAL USE at: [ 63.925258][ C1] lock_acquire+0x190/0x410 [ 63.931296][ C1] _raw_spin_lock_irq+0x60/0x80 [ 63.937680][ C1] io_submit_one+0xeb5/0x2ef0 [ 63.943891][ C1] __x64_sys_io_submit+0x1bd/0x570 [ 63.950537][ C1] do_syscall_64+0xfa/0x760 [ 63.956573][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 63.963994][ C1] } [ 63.966485][ C1] ... key at: [] __key.54358+0x0/0x40 [ 63.973913][ C1] ... acquired at: [ 63.977704][ C1] mark_lock+0x517/0x1220 [ 63.982788][ C1] __lock_acquire+0x1e8e/0x4a00 [ 63.987792][ C1] lock_acquire+0x190/0x410 [ 63.992442][ C1] _raw_spin_lock_irq+0x60/0x80 [ 63.997440][ C1] free_ioctx_users+0x2d/0x490 [ 64.002418][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 64.008735][ C1] rcu_core+0x581/0x1560 [ 64.013136][ C1] rcu_core_si+0x9/0x10 [ 64.017445][ C1] __do_softirq+0x262/0x98c [ 64.022103][ C1] irq_exit+0x19b/0x1e0 [ 64.026407][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 64.032100][ C1] apic_timer_interrupt+0xf/0x20 [ 64.037209][ C1] native_safe_halt+0xe/0x10 [ 64.041953][ C1] default_enter_idle+0x71/0xf0 [ 64.046949][ C1] cpuidle_enter_state+0xef/0xfb0 [ 64.052120][ C1] cpuidle_enter+0x4f/0xa0 [ 64.056684][ C1] do_idle+0x45f/0x6e0 [ 64.060898][ C1] cpu_startup_entry+0x1b/0x20 [ 64.065847][ C1] start_secondary+0x2f4/0x410 [ 64.070759][ C1] secondary_startup_64+0xa4/0xb0 [ 64.075927][ C1] [ 64.078227][ C1] [ 64.078227][ C1] stack backtrace: [ 64.084093][ C1] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.3.0-rc6-next-20190830 #75 [ 64.092383][ C1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 64.102408][ C1] Call Trace: [ 64.105700][ C1] [ 64.108536][ C1] dump_stack+0x172/0x1f0 [ 64.112847][ C1] print_irq_inversion_bug.part.0+0x2e4/0x2f1 [ 64.118894][ C1] check_usage_forwards.cold+0x20/0x29 [ 64.124327][ C1] ? check_usage_backwards+0x330/0x330 [ 64.129758][ C1] ? save_trace+0x3e/0x8c0 [ 64.134152][ C1] mark_lock+0x517/0x1220 [ 64.138450][ C1] ? check_usage_backwards+0x330/0x330 [ 64.143881][ C1] __lock_acquire+0x1e8e/0x4a00 [ 64.148704][ C1] ? __kasan_check_read+0x11/0x20 [ 64.153700][ C1] ? mark_lock+0xc2/0x1220 [ 64.158094][ C1] ? mark_held_locks+0xf0/0xf0 [ 64.162834][ C1] lock_acquire+0x190/0x410 [ 64.167315][ C1] ? free_ioctx_users+0x2d/0x490 [ 64.172231][ C1] _raw_spin_lock_irq+0x60/0x80 [ 64.177053][ C1] ? free_ioctx_users+0x2d/0x490 [ 64.182068][ C1] free_ioctx_users+0x2d/0x490 [ 64.186803][ C1] ? rcu_dynticks_curr_cpu_in_eqs+0x54/0xb0 [ 64.192684][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 64.198807][ C1] ? percpu_ref_exit+0xd0/0xd0 [ 64.203551][ C1] rcu_core+0x581/0x1560 [ 64.207765][ C1] ? __rcu_read_unlock+0x6b0/0x6b0 [ 64.213287][ C1] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 64.218805][ C1] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 64.224760][ C1] ? run_rebalance_domains+0x227/0x2d0 [ 64.230206][ C1] rcu_core_si+0x9/0x10 [ 64.234333][ C1] __do_softirq+0x262/0x98c [ 64.238815][ C1] ? sched_clock_cpu+0x1b/0x1b0 [ 64.243665][ C1] irq_exit+0x19b/0x1e0 [ 64.247802][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 64.253319][ C1] apic_timer_interrupt+0xf/0x20 [ 64.258221][ C1] [ 64.261136][ C1] RIP: 0010:native_safe_halt+0xe/0x10 [ 64.266481][ C1] Code: 38 c1 69 fa eb 8a 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d 64 b8 64 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 54 b8 64 00 fb f4 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 e8 5e a7 1c fa e8 69 [ 64.286053][ C1] RSP: 0018:ffff8880a98dfcd0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 [ 64.294434][ C1] RAX: 1ffffffff11e5db7 RBX: 0000000000000000 RCX: 0000000000000000 [ 64.302390][ C1] RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880a98d0bdc [ 64.310332][ C1] RBP: ffff8880a98dfd00 R08: ffff8880a98d0340 R09: 0000000000000000 [ 64.318277][ C1] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 [ 64.326227][ C1] R13: 0000000000000000 R14: 0000000000000060 R15: 0000000000000001 [ 64.334183][ C1] ? default_idle+0x4e/0x360 [ 64.338743][ C1] default_enter_idle+0x71/0xf0 [ 64.343570][ C1] cpuidle_enter_state+0xef/0xfb0 [ 64.348564][ C1] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [