[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 54.370279][ T26] audit: type=1800 audit(1567463200.427:25): pid=8509 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 54.391815][ T26] audit: type=1800 audit(1567463200.427:26): pid=8509 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 54.412318][ T26] audit: type=1800 audit(1567463200.427:27): pid=8509 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 '10.128.0.183' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 64.511305][ C1] [ 64.513684][ C1] ======================================================== [ 64.520845][ C1] WARNING: possible irq lock inversion dependency detected [ 64.528009][ C1] 5.3.0-rc6-next-20190830 #75 Not tainted [ 64.533824][ C1] -------------------------------------------------------- [ 64.540985][ C1] swapper/1/0 just changed the state of lock: [ 64.547019][ C1] ffff88809a059b58 (&(&ctx->ctx_lock)->rlock){..-.}, at: free_ioctx_users+0x2d/0x490 [ 64.556456][ C1] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 64.563963][ C1] (&fiq->waitq){+.+.} [ 64.563969][ C1] [ 64.563969][ C1] [ 64.563969][ C1] and interrupts could create inverse lock ordering between them. [ 64.563969][ C1] [ 64.582278][ C1] [ 64.582278][ C1] other info that might help us debug this: [ 64.590307][ C1] Possible interrupt unsafe locking scenario: [ 64.590307][ C1] [ 64.598596][ C1] CPU0 CPU1 [ 64.603946][ C1] ---- ---- [ 64.609292][ C1] lock(&fiq->waitq); [ 64.613330][ C1] local_irq_disable(); [ 64.620064][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 64.627745][ C1] lock(&fiq->waitq); [ 64.634300][ C1] [ 64.637724][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 64.643065][ C1] [ 64.643065][ C1] *** DEADLOCK *** [ 64.643065][ C1] [ 64.651188][ C1] 2 locks held by swapper/1/0: [ 64.655921][ C1] #0: ffffffff88fa7e40 (rcu_callback){....}, at: rcu_core+0x60e/0x1560 [ 64.664262][ C1] #1: ffffffff88fa7e80 (rcu_read_lock_sched){....}, at: percpu_ref_switch_to_atomic_rcu+0x20e/0x570 [ 64.675086][ C1] [ 64.675086][ C1] the shortest dependencies between 2nd lock and 1st lock: [ 64.684470][ C1] -> (&fiq->waitq){+.+.} { [ 64.688946][ C1] HARDIRQ-ON-W at: [ 64.692991][ C1] lock_acquire+0x190/0x410 [ 64.699301][ C1] _raw_spin_lock+0x2f/0x40 [ 64.705600][ C1] flush_bg_queue+0x1f1/0x3b0 [ 64.712071][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 64.719843][ C1] fuse_request_send_background+0x58/0x110 [ 64.727453][ C1] cuse_channel_open+0x5c3/0x839 [ 64.734183][ C1] misc_open+0x395/0x4c0 [ 64.740218][ C1] chrdev_open+0x245/0x6b0 [ 64.746430][ C1] do_dentry_open+0x4df/0x1250 [ 64.752986][ C1] vfs_open+0xa0/0xd0 [ 64.758761][ C1] path_openat+0x10e9/0x46d0 [ 64.765153][ C1] do_filp_open+0x1a1/0x280 [ 64.771448][ C1] do_sys_open+0x3fe/0x5d0 [ 64.777655][ C1] __x64_sys_openat+0x9d/0x100 [ 64.784226][ C1] do_syscall_64+0xfa/0x760 [ 64.790525][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 64.798203][ C1] SOFTIRQ-ON-W at: [ 64.802257][ C1] lock_acquire+0x190/0x410 [ 64.808555][ C1] _raw_spin_lock+0x2f/0x40 [ 64.814849][ C1] flush_bg_queue+0x1f1/0x3b0 [ 64.821318][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 64.829097][ C1] fuse_request_send_background+0x58/0x110 [ 64.836695][ C1] cuse_channel_open+0x5c3/0x839 [ 64.843426][ C1] misc_open+0x395/0x4c0 [ 64.849463][ C1] chrdev_open+0x245/0x6b0 [ 64.855673][ C1] do_dentry_open+0x4df/0x1250 [ 64.862234][ C1] vfs_open+0xa0/0xd0 [ 64.868008][ C1] path_openat+0x10e9/0x46d0 [ 64.874413][ C1] do_filp_open+0x1a1/0x280 [ 64.880708][ C1] do_sys_open+0x3fe/0x5d0 [ 64.886917][ C1] __x64_sys_openat+0x9d/0x100 [ 64.893476][ C1] do_syscall_64+0xfa/0x760 [ 64.899776][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 64.907471][ C1] INITIAL USE at: [ 64.911427][ C1] lock_acquire+0x190/0x410 [ 64.917636][ C1] _raw_spin_lock+0x2f/0x40 [ 64.923853][ C1] flush_bg_queue+0x1f1/0x3b0 [ 64.930236][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 64.937929][ C1] fuse_request_send_background+0x58/0x110 [ 64.945442][ C1] cuse_channel_open+0x5c3/0x839 [ 64.952086][ C1] misc_open+0x395/0x4c0 [ 64.958036][ C1] chrdev_open+0x245/0x6b0 [ 64.964171][ C1] do_dentry_open+0x4df/0x1250 [ 64.970640][ C1] vfs_open+0xa0/0xd0 [ 64.976336][ C1] path_openat+0x10e9/0x46d0 [ 64.982646][ C1] do_filp_open+0x1a1/0x280 [ 64.988858][ C1] do_sys_open+0x3fe/0x5d0 [ 64.994979][ C1] __x64_sys_openat+0x9d/0x100 [ 65.001452][ C1] do_syscall_64+0xfa/0x760 [ 65.007663][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 65.015255][ C1] } [ 65.017822][ C1] ... key at: [] __key.44810+0x0/0x40 [ 65.025331][ C1] ... acquired at: [ 65.029200][ C1] _raw_spin_lock+0x2f/0x40 [ 65.033854][ C1] io_submit_one+0xefa/0x2ef0 [ 65.038689][ C1] __x64_sys_io_submit+0x1bd/0x570 [ 65.043953][ C1] do_syscall_64+0xfa/0x760 [ 65.048609][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 65.054683][ C1] [ 65.056987][ C1] -> (&(&ctx->ctx_lock)->rlock){..-.} { [ 65.062512][ C1] IN-SOFTIRQ-W at: [ 65.066475][ C1] lock_acquire+0x190/0x410 [ 65.072602][ C1] _raw_spin_lock_irq+0x60/0x80 [ 65.079076][ C1] free_ioctx_users+0x2d/0x490 [ 65.085465][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 65.093238][ C1] rcu_core+0x581/0x1560 [ 65.099098][ C1] rcu_core_si+0x9/0x10 [ 65.104928][ C1] __do_softirq+0x262/0x98c [ 65.111065][ C1] irq_exit+0x19b/0x1e0 [ 65.116852][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 65.124026][ C1] apic_timer_interrupt+0xf/0x20 [ 65.130596][ C1] native_safe_halt+0xe/0x10 [ 65.136812][ C1] default_enter_idle+0x71/0xf0 [ 65.143282][ C1] cpuidle_enter_state+0xef/0xfb0 [ 65.149925][ C1] cpuidle_enter+0x4f/0xa0 [ 65.155962][ C1] do_idle+0x45f/0x6e0 [ 65.161658][ C1] cpu_startup_entry+0x1b/0x20 [ 65.168046][ C1] start_secondary+0x2f4/0x410 [ 65.174430][ C1] secondary_startup_64+0xa4/0xb0 [ 65.181091][ C1] INITIAL USE at: [ 65.184986][ C1] lock_acquire+0x190/0x410 [ 65.191025][ C1] _raw_spin_lock_irq+0x60/0x80 [ 65.197410][ C1] io_submit_one+0xeb5/0x2ef0 [ 65.203622][ C1] __x64_sys_io_submit+0x1bd/0x570 [ 65.210265][ C1] do_syscall_64+0xfa/0x760 [ 65.216301][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 65.223731][ C1] } [ 65.226212][ C1] ... key at: [] __key.54358+0x0/0x40 [ 65.233644][ C1] ... acquired at: [ 65.237434][ C1] mark_lock+0x517/0x1220 [ 65.241908][ C1] __lock_acquire+0x1e8e/0x4a00 [ 65.246904][ C1] lock_acquire+0x190/0x410 [ 65.251551][ C1] _raw_spin_lock_irq+0x60/0x80 [ 65.256544][ C1] free_ioctx_users+0x2d/0x490 [ 65.261468][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 65.267772][ C1] rcu_core+0x581/0x1560 [ 65.272168][ C1] rcu_core_si+0x9/0x10 [ 65.276481][ C1] __do_softirq+0x262/0x98c [ 65.281133][ C1] irq_exit+0x19b/0x1e0 [ 65.288131][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 65.293828][ C1] apic_timer_interrupt+0xf/0x20 [ 65.298915][ C1] native_safe_halt+0xe/0x10 [ 65.303658][ C1] default_enter_idle+0x71/0xf0 [ 65.308699][ C1] cpuidle_enter_state+0xef/0xfb0 [ 65.314390][ C1] cpuidle_enter+0x4f/0xa0 [ 65.318954][ C1] do_idle+0x45f/0x6e0 [ 65.323170][ C1] cpu_startup_entry+0x1b/0x20 [ 65.328112][ C1] start_secondary+0x2f4/0x410 [ 65.333046][ C1] secondary_startup_64+0xa4/0xb0 [ 65.338240][ C1] [ 65.340537][ C1] [ 65.340537][ C1] stack backtrace: [ 65.346414][ C1] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.3.0-rc6-next-20190830 #75 [ 65.354725][ C1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 65.364755][ C1] Call Trace: [ 65.368011][ C1] [ 65.370843][ C1] dump_stack+0x172/0x1f0 [ 65.375148][ C1] print_irq_inversion_bug.part.0+0x2e4/0x2f1 [ 65.381199][ C1] check_usage_forwards.cold+0x20/0x29 [ 65.386639][ C1] ? check_usage_backwards+0x330/0x330 [ 65.392592][ C1] ? save_trace+0x3e/0x8c0 [ 65.396982][ C1] mark_lock+0x517/0x1220 [ 65.401285][ C1] ? check_usage_backwards+0x330/0x330 [ 65.406718][ C1] __lock_acquire+0x1e8e/0x4a00 [ 65.411627][ C1] ? __kasan_check_read+0x11/0x20 [ 65.416620][ C1] ? mark_lock+0xc2/0x1220 [ 65.421009][ C1] ? mark_held_locks+0xf0/0xf0 [ 65.425768][ C1] lock_acquire+0x190/0x410 [ 65.430242][ C1] ? free_ioctx_users+0x2d/0x490 [ 65.435153][ C1] _raw_spin_lock_irq+0x60/0x80 [ 65.439973][ C1] ? free_ioctx_users+0x2d/0x490 [ 65.444890][ C1] free_ioctx_users+0x2d/0x490 [ 65.449637][ C1] ? rcu_dynticks_curr_cpu_in_eqs+0x54/0xb0 [ 65.455502][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 65.461630][ C1] ? percpu_ref_exit+0xd0/0xd0 [ 65.466364][ C1] rcu_core+0x581/0x1560 [ 65.470580][ C1] ? __rcu_read_unlock+0x6b0/0x6b0 [ 65.475662][ C1] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 65.481205][ C1] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 65.487163][ C1] ? run_rebalance_domains+0x227/0x2d0 [ 65.492610][ C1] rcu_core_si+0x9/0x10 [ 65.496739][ C1] __do_softirq+0x262/0x98c [ 65.501224][ C1] ? sched_clock_cpu+0x1b/0x1b0 [ 65.506052][ C1] irq_exit+0x19b/0x1e0 [ 65.510195][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 65.515711][ C1] apic_timer_interrupt+0xf/0x20 [ 65.520625][ C1] [ 65.523628][ C1] RIP: 0010:native_safe_halt+0xe/0x10 [ 65.528990][ 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 [ 65.548562][ C1] RSP: 0018:ffff8880a98dfcd0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 [ 65.556946][ C1] RAX: 1ffffffff11e5db7 RBX: 0000000000000000 RCX: 0000000000000000 [ 65.564889][ C1] RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880a98d0bdc [ 65.572832][ C1] RBP: ffff8880a98dfd00 R08: ffff8880a98d0340 R09: 0000000000000000 [ 65.580774][ C1] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 [ 65.588720][ C1] R13: 0000000000000000 R14: 0000000000000060 R15: 0000000000000001 [ 65.596679][ C1] ? default_idle+0x4e/0x360 [ 65.601249][ C1] default_enter_idle+0x71/0xf0 [ 65.606080][ C1] cpuidle_enter_state+0xef/0xfb0 [ 65.611078][ C1] ? __sanitizer_cov_trace_const_cmp4+0