[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 56.870306][ T26] audit: type=1800 audit(1567473875.062:25): pid=8556 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 56.891808][ T26] audit: type=1800 audit(1567473875.072:26): pid=8556 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 56.912878][ T26] audit: type=1800 audit(1567473875.072:27): pid=8556 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 '10.128.0.234' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 67.530620][ C1] [ 67.532989][ C1] ======================================================== [ 67.540155][ C1] WARNING: possible irq lock inversion dependency detected [ 67.547409][ C1] 5.3.0-rc6-next-20190830 #75 Not tainted [ 67.553097][ C1] -------------------------------------------------------- [ 67.560280][ C1] swapper/1/0 just changed the state of lock: [ 67.566315][ C1] ffff8880a44ddb58 (&(&ctx->ctx_lock)->rlock){..-.}, at: free_ioctx_users+0x2d/0x490 [ 67.575751][ C1] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 67.583260][ C1] (&fiq->waitq){+.+.} [ 67.583266][ C1] [ 67.583266][ C1] [ 67.583266][ C1] and interrupts could create inverse lock ordering between them. [ 67.583266][ C1] [ 67.601579][ C1] [ 67.601579][ C1] other info that might help us debug this: [ 67.609611][ C1] Possible interrupt unsafe locking scenario: [ 67.609611][ C1] [ 67.617900][ C1] CPU0 CPU1 [ 67.623245][ C1] ---- ---- [ 67.628586][ C1] lock(&fiq->waitq); [ 67.632649][ C1] local_irq_disable(); [ 67.639378][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 67.647065][ C1] lock(&fiq->waitq); [ 67.653628][ C1] [ 67.657060][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 67.662412][ C1] [ 67.662412][ C1] *** DEADLOCK *** [ 67.662412][ C1] [ 67.670540][ C1] 2 locks held by swapper/1/0: [ 67.675272][ C1] #0: ffffffff88fa7e40 (rcu_callback){....}, at: rcu_core+0x60e/0x1560 [ 67.683587][ C1] #1: ffffffff88fa7e80 (rcu_read_lock_sched){....}, at: percpu_ref_switch_to_atomic_rcu+0x20e/0x570 [ 67.694412][ C1] [ 67.694412][ C1] the shortest dependencies between 2nd lock and 1st lock: [ 67.703774][ C1] -> (&fiq->waitq){+.+.} { [ 67.708261][ C1] HARDIRQ-ON-W at: [ 67.712329][ C1] lock_acquire+0x190/0x410 [ 67.718633][ C1] _raw_spin_lock+0x2f/0x40 [ 67.724933][ C1] flush_bg_queue+0x1f1/0x3b0 [ 67.731418][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 67.739190][ C1] fuse_request_send_background+0x58/0x110 [ 67.746791][ C1] cuse_channel_open+0x5c3/0x839 [ 67.753540][ C1] misc_open+0x395/0x4c0 [ 67.759577][ C1] chrdev_open+0x245/0x6b0 [ 67.765803][ C1] do_dentry_open+0x4df/0x1250 [ 67.772364][ C1] vfs_open+0xa0/0xd0 [ 67.778141][ C1] path_openat+0x10e9/0x46d0 [ 67.784544][ C1] do_filp_open+0x1a1/0x280 [ 67.790857][ C1] do_sys_open+0x3fe/0x5d0 [ 67.797065][ C1] __x64_sys_openat+0x9d/0x100 [ 67.803625][ C1] do_syscall_64+0xfa/0x760 [ 67.809927][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 67.817610][ C1] SOFTIRQ-ON-W at: [ 67.821656][ C1] lock_acquire+0x190/0x410 [ 67.827954][ C1] _raw_spin_lock+0x2f/0x40 [ 67.834252][ C1] flush_bg_queue+0x1f1/0x3b0 [ 67.840727][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 67.848500][ C1] fuse_request_send_background+0x58/0x110 [ 67.856121][ C1] cuse_channel_open+0x5c3/0x839 [ 67.862854][ C1] misc_open+0x395/0x4c0 [ 67.868895][ C1] chrdev_open+0x245/0x6b0 [ 67.875121][ C1] do_dentry_open+0x4df/0x1250 [ 67.881695][ C1] vfs_open+0xa0/0xd0 [ 67.887473][ C1] path_openat+0x10e9/0x46d0 [ 67.893871][ C1] do_filp_open+0x1a1/0x280 [ 67.900181][ C1] do_sys_open+0x3fe/0x5d0 [ 67.906391][ C1] __x64_sys_openat+0x9d/0x100 [ 67.912955][ C1] do_syscall_64+0xfa/0x760 [ 67.919283][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 67.926965][ C1] INITIAL USE at: [ 67.930933][ C1] lock_acquire+0x190/0x410 [ 67.937163][ C1] _raw_spin_lock+0x2f/0x40 [ 67.943432][ C1] flush_bg_queue+0x1f1/0x3b0 [ 67.949829][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 67.957522][ C1] fuse_request_send_background+0x58/0x110 [ 67.965041][ C1] cuse_channel_open+0x5c3/0x839 [ 67.971706][ C1] misc_open+0x395/0x4c0 [ 67.977661][ C1] chrdev_open+0x245/0x6b0 [ 67.983802][ C1] do_dentry_open+0x4df/0x1250 [ 67.990275][ C1] vfs_open+0xa0/0xd0 [ 67.995966][ C1] path_openat+0x10e9/0x46d0 [ 68.002295][ C1] do_filp_open+0x1a1/0x280 [ 68.008507][ C1] do_sys_open+0x3fe/0x5d0 [ 68.014632][ C1] __x64_sys_openat+0x9d/0x100 [ 68.021118][ C1] do_syscall_64+0xfa/0x760 [ 68.027333][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 68.034930][ C1] } [ 68.037501][ C1] ... key at: [] __key.44810+0x0/0x40 [ 68.045010][ C1] ... acquired at: [ 68.048882][ C1] _raw_spin_lock+0x2f/0x40 [ 68.053532][ C1] io_submit_one+0xefa/0x2ef0 [ 68.058355][ C1] __x64_sys_io_submit+0x1bd/0x570 [ 68.063624][ C1] do_syscall_64+0xfa/0x760 [ 68.068366][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 68.074464][ C1] [ 68.076770][ C1] -> (&(&ctx->ctx_lock)->rlock){..-.} { [ 68.082401][ C1] IN-SOFTIRQ-W at: [ 68.086368][ C1] lock_acquire+0x190/0x410 [ 68.092499][ C1] _raw_spin_lock_irq+0x60/0x80 [ 68.099017][ C1] free_ioctx_users+0x2d/0x490 [ 68.105422][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 68.113205][ C1] rcu_core+0x581/0x1560 [ 68.119073][ C1] rcu_core_si+0x9/0x10 [ 68.124852][ C1] __do_softirq+0x262/0x98c [ 68.130997][ C1] irq_exit+0x19b/0x1e0 [ 68.136774][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 68.143955][ C1] apic_timer_interrupt+0xf/0x20 [ 68.150515][ C1] native_safe_halt+0xe/0x10 [ 68.156731][ C1] default_enter_idle+0x71/0xf0 [ 68.163204][ C1] cpuidle_enter_state+0xef/0xfb0 [ 68.169850][ C1] cpuidle_enter+0x4f/0xa0 [ 68.175891][ C1] do_idle+0x45f/0x6e0 [ 68.181597][ C1] cpu_startup_entry+0x1b/0x20 [ 68.187991][ C1] start_secondary+0x2f4/0x410 [ 68.194388][ C1] secondary_startup_64+0xa4/0xb0 [ 68.201051][ C1] INITIAL USE at: [ 68.204925][ C1] lock_acquire+0x190/0x410 [ 68.210966][ C1] _raw_spin_lock_irq+0x60/0x80 [ 68.217384][ C1] io_submit_one+0xeb5/0x2ef0 [ 68.223604][ C1] __x64_sys_io_submit+0x1bd/0x570 [ 68.230256][ C1] do_syscall_64+0xfa/0x760 [ 68.236303][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 68.243728][ C1] } [ 68.246222][ C1] ... key at: [] __key.54358+0x0/0x40 [ 68.253648][ C1] ... acquired at: [ 68.257435][ C1] mark_lock+0x517/0x1220 [ 68.261911][ C1] __lock_acquire+0x1e8e/0x4a00 [ 68.266907][ C1] lock_acquire+0x190/0x410 [ 68.271556][ C1] _raw_spin_lock_irq+0x60/0x80 [ 68.276554][ C1] free_ioctx_users+0x2d/0x490 [ 68.281465][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 68.287762][ C1] rcu_core+0x581/0x1560 [ 68.292149][ C1] rcu_core_si+0x9/0x10 [ 68.297018][ C1] __do_softirq+0x262/0x98c [ 68.301671][ C1] irq_exit+0x19b/0x1e0 [ 68.305975][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 68.311670][ C1] apic_timer_interrupt+0xf/0x20 [ 68.316766][ C1] native_safe_halt+0xe/0x10 [ 68.321504][ C1] default_enter_idle+0x71/0xf0 [ 68.326501][ C1] cpuidle_enter_state+0xef/0xfb0 [ 68.331670][ C1] cpuidle_enter+0x4f/0xa0 [ 68.336230][ C1] do_idle+0x45f/0x6e0 [ 68.340448][ C1] cpu_startup_entry+0x1b/0x20 [ 68.345377][ C1] start_secondary+0x2f4/0x410 [ 68.350287][ C1] secondary_startup_64+0xa4/0xb0 [ 68.355453][ C1] [ 68.357762][ C1] [ 68.357762][ C1] stack backtrace: [ 68.363626][ C1] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.3.0-rc6-next-20190830 #75 [ 68.371919][ C1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 68.381963][ C1] Call Trace: [ 68.385231][ C1] [ 68.388063][ C1] dump_stack+0x172/0x1f0 [ 68.392369][ C1] print_irq_inversion_bug.part.0+0x2e4/0x2f1 [ 68.398412][ C1] check_usage_forwards.cold+0x20/0x29 [ 68.403844][ C1] ? check_usage_backwards+0x330/0x330 [ 68.409289][ C1] ? save_trace+0x3e/0x8c0 [ 68.413679][ C1] mark_lock+0x517/0x1220 [ 68.417983][ C1] ? check_usage_backwards+0x330/0x330 [ 68.424631][ C1] __lock_acquire+0x1e8e/0x4a00 [ 68.429453][ C1] ? __kasan_check_read+0x11/0x20 [ 68.434449][ C1] ? mark_lock+0xc2/0x1220 [ 68.438839][ C1] ? mark_held_locks+0xf0/0xf0 [ 68.443576][ C1] lock_acquire+0x190/0x410 [ 68.448052][ C1] ? free_ioctx_users+0x2d/0x490 [ 68.452988][ C1] _raw_spin_lock_irq+0x60/0x80 [ 68.457810][ C1] ? free_ioctx_users+0x2d/0x490 [ 68.462720][ C1] free_ioctx_users+0x2d/0x490 [ 68.467458][ C1] ? rcu_dynticks_curr_cpu_in_eqs+0x54/0xb0 [ 68.473325][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 68.479452][ C1] ? percpu_ref_exit+0xd0/0xd0 [ 68.484186][ C1] rcu_core+0x581/0x1560 [ 68.488402][ C1] ? __rcu_read_unlock+0x6b0/0x6b0 [ 68.493551][ C1] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 68.499073][ C1] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 68.505043][ C1] ? run_rebalance_domains+0x227/0x2d0 [ 68.510499][ C1] rcu_core_si+0x9/0x10 [ 68.514631][ C1] __do_softirq+0x262/0x98c [ 68.519120][ C1] ? sched_clock_cpu+0x1b/0x1b0 [ 68.523947][ C1] irq_exit+0x19b/0x1e0 [ 68.528076][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 68.533594][ C1] apic_timer_interrupt+0xf/0x20 [ 68.538501][ C1] [ 68.541415][ C1] RIP: 0010:native_safe_halt+0xe/0x10 [ 68.546776][ 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 [ 68.566354][ C1] RSP: 0018:ffff8880a98dfcd0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 [ 68.574739][ C1] RAX: 1ffffffff11e5db7 RBX: 0000000000000000 RCX: 0000000000000000 [ 68.582682][ C1] RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880a98d0bdc [ 68.590648][ C1] RBP: ffff8880a98dfd00 R08: ffff8880a98d0340 R09: 0000000000000000 [ 68.598603][ C1] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 [ 68.606561][ C1] R13: 0000000000000000 R14: 0000000000000060 R15: 0000000000000001 [ 68.614517][ C1] ? default_idle+0x4e/0x360 [ 68.619080][ C1] default_enter_idle+0x71/0xf0 [ 68.623904][ C1] cpuidle_enter_state+0xef/0xfb0 [ 68.628915][ C1] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [