[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 54.387350][ T26] audit: type=1800 audit(1567352401.476:25): pid=8516 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 54.425854][ T26] audit: type=1800 audit(1567352401.476:26): pid=8516 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 54.450097][ T26] audit: type=1800 audit(1567352401.486:27): pid=8516 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: [ 63.315813][ C1] [ 63.318152][ C1] ======================================================== [ 63.325313][ C1] WARNING: possible irq lock inversion dependency detected [ 63.332480][ C1] 5.3.0-rc6-next-20190830 #75 Not tainted [ 63.339222][ C1] -------------------------------------------------------- [ 63.346392][ C1] swapper/1/0 just changed the state of lock: [ 63.352426][ C1] ffff8880994ffb58 (&(&ctx->ctx_lock)->rlock){..-.}, at: free_ioctx_users+0x2d/0x490 [ 63.361876][ C1] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 63.369383][ C1] (&fiq->waitq){+.+.} [ 63.369389][ C1] [ 63.369389][ C1] [ 63.369389][ C1] and interrupts could create inverse lock ordering between them. [ 63.369389][ C1] [ 63.387699][ C1] [ 63.387699][ C1] other info that might help us debug this: [ 63.395729][ C1] Possible interrupt unsafe locking scenario: [ 63.395729][ C1] [ 63.404017][ C1] CPU0 CPU1 [ 63.409355][ C1] ---- ---- [ 63.414692][ C1] lock(&fiq->waitq); [ 63.418731][ C1] local_irq_disable(); [ 63.425458][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 63.433143][ C1] lock(&fiq->waitq); [ 63.439714][ C1] [ 63.443143][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 63.448484][ C1] [ 63.448484][ C1] *** DEADLOCK *** [ 63.448484][ C1] [ 63.456601][ C1] 2 locks held by swapper/1/0: [ 63.461328][ C1] #0: ffffffff88fa7e40 (rcu_callback){....}, at: rcu_core+0x60e/0x1560 [ 63.469633][ C1] #1: ffffffff88fa7e80 (rcu_read_lock_sched){....}, at: percpu_ref_switch_to_atomic_rcu+0x20e/0x570 [ 63.480456][ C1] [ 63.480456][ C1] the shortest dependencies between 2nd lock and 1st lock: [ 63.489798][ C1] -> (&fiq->waitq){+.+.} { [ 63.494274][ C1] HARDIRQ-ON-W at: [ 63.498317][ C1] lock_acquire+0x190/0x410 [ 63.504619][ C1] _raw_spin_lock+0x2f/0x40 [ 63.510920][ C1] flush_bg_queue+0x1f1/0x3b0 [ 63.517389][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 63.525163][ C1] fuse_request_send_background+0x58/0x110 [ 63.532761][ C1] cuse_channel_open+0x5c3/0x839 [ 63.539492][ C1] misc_open+0x395/0x4c0 [ 63.545532][ C1] chrdev_open+0x245/0x6b0 [ 63.551745][ C1] do_dentry_open+0x4df/0x1250 [ 63.558303][ C1] vfs_open+0xa0/0xd0 [ 63.564079][ C1] path_openat+0x10e9/0x46d0 [ 63.570464][ C1] do_filp_open+0x1a1/0x280 [ 63.576760][ C1] do_sys_open+0x3fe/0x5d0 [ 63.582966][ C1] __x64_sys_openat+0x9d/0x100 [ 63.589525][ C1] do_syscall_64+0xfa/0x760 [ 63.595824][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 63.603504][ C1] SOFTIRQ-ON-W at: [ 63.607547][ C1] lock_acquire+0x190/0x410 [ 63.613844][ C1] _raw_spin_lock+0x2f/0x40 [ 63.620138][ C1] flush_bg_queue+0x1f1/0x3b0 [ 63.626610][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 63.634405][ C1] fuse_request_send_background+0x58/0x110 [ 63.642007][ C1] cuse_channel_open+0x5c3/0x839 [ 63.648738][ C1] misc_open+0x395/0x4c0 [ 63.654775][ C1] chrdev_open+0x245/0x6b0 [ 63.660985][ C1] do_dentry_open+0x4df/0x1250 [ 63.667555][ C1] vfs_open+0xa0/0xd0 [ 63.673340][ C1] path_openat+0x10e9/0x46d0 [ 63.679722][ C1] do_filp_open+0x1a1/0x280 [ 63.686021][ C1] do_sys_open+0x3fe/0x5d0 [ 63.692242][ C1] __x64_sys_openat+0x9d/0x100 [ 63.698800][ C1] do_syscall_64+0xfa/0x760 [ 63.706143][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 63.713824][ C1] INITIAL USE at: [ 63.717782][ C1] lock_acquire+0x190/0x410 [ 63.723990][ C1] _raw_spin_lock+0x2f/0x40 [ 63.730202][ C1] flush_bg_queue+0x1f1/0x3b0 [ 63.736587][ C1] fuse_request_queue_background+0x2f8/0x5b0 [ 63.744269][ C1] fuse_request_send_background+0x58/0x110 [ 63.751778][ C1] cuse_channel_open+0x5c3/0x839 [ 63.758422][ C1] misc_open+0x395/0x4c0 [ 63.764373][ C1] chrdev_open+0x245/0x6b0 [ 63.770498][ C1] do_dentry_open+0x4df/0x1250 [ 63.776970][ C1] vfs_open+0xa0/0xd0 [ 63.782665][ C1] path_openat+0x10e9/0x46d0 [ 63.788976][ C1] do_filp_open+0x1a1/0x280 [ 63.795188][ C1] do_sys_open+0x3fe/0x5d0 [ 63.801306][ C1] __x64_sys_openat+0x9d/0x100 [ 63.807778][ C1] do_syscall_64+0xfa/0x760 [ 63.813989][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 63.821584][ C1] } [ 63.824149][ C1] ... key at: [] __key.44810+0x0/0x40 [ 63.831655][ C1] ... acquired at: [ 63.835523][ C1] _raw_spin_lock+0x2f/0x40 [ 63.840171][ C1] io_submit_one+0xefa/0x2ef0 [ 63.845002][ C1] __x64_sys_io_submit+0x1bd/0x570 [ 63.850257][ C1] do_syscall_64+0xfa/0x760 [ 63.854904][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 63.860932][ C1] [ 63.863228][ C1] -> (&(&ctx->ctx_lock)->rlock){..-.} { [ 63.868760][ C1] IN-SOFTIRQ-W at: [ 63.872719][ C1] lock_acquire+0x190/0x410 [ 63.878841][ C1] _raw_spin_lock_irq+0x60/0x80 [ 63.885313][ C1] free_ioctx_users+0x2d/0x490 [ 63.891708][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 63.899480][ C1] rcu_core+0x581/0x1560 [ 63.905351][ C1] rcu_core_si+0x9/0x10 [ 63.911131][ C1] __do_softirq+0x262/0x98c [ 63.917255][ C1] irq_exit+0x19b/0x1e0 [ 63.923029][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 63.930195][ C1] apic_timer_interrupt+0xf/0x20 [ 63.936853][ C1] native_safe_halt+0xe/0x10 [ 63.943067][ C1] default_enter_idle+0x71/0xf0 [ 63.949539][ C1] cpuidle_enter_state+0xef/0xfb0 [ 63.956181][ C1] cpuidle_enter+0x4f/0xa0 [ 63.962238][ C1] do_idle+0x45f/0x6e0 [ 63.967928][ C1] cpu_startup_entry+0x1b/0x20 [ 63.974313][ C1] start_secondary+0x2f4/0x410 [ 63.980697][ C1] secondary_startup_64+0xa4/0xb0 [ 63.987344][ C1] INITIAL USE at: [ 63.991215][ C1] lock_acquire+0x190/0x410 [ 63.997249][ C1] _raw_spin_lock_irq+0x60/0x80 [ 64.003634][ C1] io_submit_one+0xeb5/0x2ef0 [ 64.009847][ C1] __x64_sys_io_submit+0x1bd/0x570 [ 64.016495][ C1] do_syscall_64+0xfa/0x760 [ 64.022535][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 64.029956][ C1] } [ 64.032440][ C1] ... key at: [] __key.54358+0x0/0x40 [ 64.039861][ C1] ... acquired at: [ 64.043643][ C1] mark_lock+0x517/0x1220 [ 64.048116][ C1] __lock_acquire+0x1e8e/0x4a00 [ 64.053112][ C1] lock_acquire+0x190/0x410 [ 64.057758][ C1] _raw_spin_lock_irq+0x60/0x80 [ 64.062750][ C1] free_ioctx_users+0x2d/0x490 [ 64.067660][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 64.073955][ C1] rcu_core+0x581/0x1560 [ 64.078341][ C1] rcu_core_si+0x9/0x10 [ 64.082641][ C1] __do_softirq+0x262/0x98c [ 64.087289][ C1] irq_exit+0x19b/0x1e0 [ 64.091589][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 64.097277][ C1] apic_timer_interrupt+0xf/0x20 [ 64.102357][ C1] native_safe_halt+0xe/0x10 [ 64.107095][ C1] default_enter_idle+0x71/0xf0 [ 64.112089][ C1] cpuidle_enter_state+0xef/0xfb0 [ 64.117255][ C1] cpuidle_enter+0x4f/0xa0 [ 64.121816][ C1] do_idle+0x45f/0x6e0 [ 64.126029][ C1] cpu_startup_entry+0x1b/0x20 [ 64.130939][ C1] start_secondary+0x2f4/0x410 [ 64.135853][ C1] secondary_startup_64+0xa4/0xb0 [ 64.141015][ C1] [ 64.143316][ C1] [ 64.143316][ C1] stack backtrace: [ 64.149184][ C1] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.3.0-rc6-next-20190830 #75 [ 64.157475][ C1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 64.167507][ C1] Call Trace: [ 64.170766][ C1] [ 64.173596][ C1] dump_stack+0x172/0x1f0 [ 64.177900][ C1] print_irq_inversion_bug.part.0+0x2e4/0x2f1 [ 64.183939][ C1] check_usage_forwards.cold+0x20/0x29 [ 64.189386][ C1] ? check_usage_backwards+0x330/0x330 [ 64.194828][ C1] ? save_trace+0x3e/0x8c0 [ 64.199221][ C1] mark_lock+0x517/0x1220 [ 64.203525][ C1] ? check_usage_backwards+0x330/0x330 [ 64.208957][ C1] __lock_acquire+0x1e8e/0x4a00 [ 64.213779][ C1] ? __kasan_check_read+0x11/0x20 [ 64.218774][ C1] ? mark_lock+0xc2/0x1220 [ 64.223164][ C1] ? mark_held_locks+0xf0/0xf0 [ 64.227902][ C1] lock_acquire+0x190/0x410 [ 64.232377][ C1] ? free_ioctx_users+0x2d/0x490 [ 64.237288][ C1] _raw_spin_lock_irq+0x60/0x80 [ 64.242107][ C1] ? free_ioctx_users+0x2d/0x490 [ 64.247013][ C1] free_ioctx_users+0x2d/0x490 [ 64.251748][ C1] ? rcu_dynticks_curr_cpu_in_eqs+0x54/0xb0 [ 64.257611][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 64.263733][ C1] ? percpu_ref_exit+0xd0/0xd0 [ 64.268467][ C1] rcu_core+0x581/0x1560 [ 64.272682][ C1] ? __rcu_read_unlock+0x6b0/0x6b0 [ 64.277764][ C1] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 64.283278][ C1] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 64.289248][ C1] ? run_rebalance_domains+0x227/0x2d0 [ 64.294676][ C1] rcu_core_si+0x9/0x10 [ 64.298806][ C1] __do_softirq+0x262/0x98c [ 64.303278][ C1] ? sched_clock_cpu+0x1b/0x1b0 [ 64.308105][ C1] irq_exit+0x19b/0x1e0 [ 64.312248][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 64.317766][ C1] apic_timer_interrupt+0xf/0x20 [ 64.322671][ C1] [ 64.325583][ C1] RIP: 0010:native_safe_halt+0xe/0x10 [ 64.330929][ 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 [ 64.350503][ C1] RSP: 0018:ffff8880a98dfcd0 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 [ 64.358883][ C1] RAX: 1ffffffff11e5db7 RBX: 0000000000000000 RCX: 0000000000000000 [ 64.366829][ C1] RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880a98d0bdc [ 64.374771][ C1] RBP: ffff8880a98dfd00 R08: ffff8880a98d0340 R09: 0000000000000000 [ 64.382711][ C1] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 [ 64.390657][ C1] R13: 0000000000000000 R14: 0000000000000060 R15: 0000000000000001 [ 64.398629][ C1] ? default_idle+0x4e/0x360 [ 64.403208][ C1] default_enter_idle+0x71/0xf0 [ 64.408031][ C1] cpuidle_enter_state+0xef/0xfb0 [ 64.413030][ C1] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 64.419237][