[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 58.556682][ T26] audit: type=1800 audit(1569069261.521:25): pid=8697 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 58.582777][ T26] audit: type=1800 audit(1569069261.531:26): pid=8697 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 58.625618][ T26] audit: type=1800 audit(1569069261.531:27): pid=8697 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 '10.128.1.44' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 71.021722][ C1] [ 71.024401][ C1] ======================================================== [ 71.031580][ C1] WARNING: possible irq lock inversion dependency detected [ 71.038759][ C1] 5.3.0+ #0 Not tainted [ 71.042900][ C1] -------------------------------------------------------- [ 71.050162][ C1] swapper/1/0 just changed the state of lock: [ 71.056210][ C1] ffff88808a1b9b58 (&(&ctx->ctx_lock)->rlock){..-.}, at: free_ioctx_users+0x2d/0x490 [ 71.065689][ C1] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 71.073229][ C1] (&fiq->waitq){+.+.} [ 71.073236][ C1] [ 71.073236][ C1] [ 71.073236][ C1] and interrupts could create inverse lock ordering between them. [ 71.073236][ C1] [ 71.091600][ C1] [ 71.091600][ C1] other info that might help us debug this: [ 71.099652][ C1] Possible interrupt unsafe locking scenario: [ 71.099652][ C1] [ 71.108053][ C1] CPU0 CPU1 [ 71.113401][ C1] ---- ---- [ 71.118756][ C1] lock(&fiq->waitq); [ 71.122971][ C1] local_irq_disable(); [ 71.129788][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 71.137588][ C1] lock(&fiq->waitq); [ 71.144262][ C1] [ 71.147788][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 71.153139][ C1] [ 71.153139][ C1] *** DEADLOCK *** [ 71.153139][ C1] [ 71.161370][ C1] 2 locks held by swapper/1/0: [ 71.166219][ C1] #0: ffffffff88fab1c0 (rcu_callback){....}, at: rcu_core+0x60e/0x1560 [ 71.174557][ C1] #1: ffffffff88fab200 (rcu_read_lock_sched){....}, at: percpu_ref_switch_to_atomic_rcu+0x20e/0x570 [ 71.185484][ C1] [ 71.185484][ C1] the shortest dependencies between 2nd lock and 1st lock: [ 71.194834][ C1] -> (&fiq->waitq){+.+.} { [ 71.199377][ C1] HARDIRQ-ON-W at: [ 71.203451][ C1] lock_acquire+0x190/0x410 [ 71.209762][ C1] _raw_spin_lock+0x2f/0x40 [ 71.216117][ C1] flush_bg_queue+0x1f3/0x3c0 [ 71.222623][ C1] fuse_request_queue_background+0x2f8/0x5a0 [ 71.230425][ C1] fuse_request_send_background+0x58/0x110 [ 71.238032][ C1] cuse_channel_open+0x5ba/0x830 [ 71.244989][ C1] misc_open+0x395/0x4c0 [ 71.251060][ C1] chrdev_open+0x245/0x6b0 [ 71.257375][ C1] do_dentry_open+0x4df/0x1250 [ 71.263955][ C1] vfs_open+0xa0/0xd0 [ 71.269741][ C1] path_openat+0x10e9/0x4630 [ 71.276132][ C1] do_filp_open+0x1a1/0x280 [ 71.282523][ C1] do_sys_open+0x3fe/0x5d0 [ 71.288737][ C1] __x64_sys_openat+0x9d/0x100 [ 71.295405][ C1] do_syscall_64+0xfa/0x760 [ 71.301710][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 71.309519][ C1] SOFTIRQ-ON-W at: [ 71.313637][ C1] lock_acquire+0x190/0x410 [ 71.320189][ C1] _raw_spin_lock+0x2f/0x40 [ 71.328848][ C1] flush_bg_queue+0x1f3/0x3c0 [ 71.335416][ C1] fuse_request_queue_background+0x2f8/0x5a0 [ 71.343329][ C1] fuse_request_send_background+0x58/0x110 [ 71.350948][ C1] cuse_channel_open+0x5ba/0x830 [ 71.357695][ C1] misc_open+0x395/0x4c0 [ 71.363743][ C1] chrdev_open+0x245/0x6b0 [ 71.369981][ C1] do_dentry_open+0x4df/0x1250 [ 71.376648][ C1] vfs_open+0xa0/0xd0 [ 71.382448][ C1] path_openat+0x10e9/0x4630 [ 71.389047][ C1] do_filp_open+0x1a1/0x280 [ 71.395368][ C1] do_sys_open+0x3fe/0x5d0 [ 71.401597][ C1] __x64_sys_openat+0x9d/0x100 [ 71.408251][ C1] do_syscall_64+0xfa/0x760 [ 71.414569][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 71.422440][ C1] INITIAL USE at: [ 71.426416][ C1] lock_acquire+0x190/0x410 [ 71.433158][ C1] _raw_spin_lock+0x2f/0x40 [ 71.439385][ C1] flush_bg_queue+0x1f3/0x3c0 [ 71.445787][ C1] fuse_request_queue_background+0x2f8/0x5a0 [ 71.453494][ C1] fuse_request_send_background+0x58/0x110 [ 71.461108][ C1] cuse_channel_open+0x5ba/0x830 [ 71.467860][ C1] misc_open+0x395/0x4c0 [ 71.473847][ C1] chrdev_open+0x245/0x6b0 [ 71.480006][ C1] do_dentry_open+0x4df/0x1250 [ 71.486515][ C1] vfs_open+0xa0/0xd0 [ 71.492222][ C1] path_openat+0x10e9/0x4630 [ 71.499136][ C1] do_filp_open+0x1a1/0x280 [ 71.505360][ C1] do_sys_open+0x3fe/0x5d0 [ 71.511505][ C1] __x64_sys_openat+0x9d/0x100 [ 71.518127][ C1] do_syscall_64+0xfa/0x760 [ 71.524785][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 71.532483][ C1] } [ 71.535065][ C1] ... key at: [] __key.44708+0x0/0x40 [ 71.542665][ C1] ... acquired at: [ 71.546633][ C1] _raw_spin_lock+0x2f/0x40 [ 71.551290][ C1] io_submit_one+0xefa/0x2ef0 [ 71.556133][ C1] __x64_sys_io_submit+0x1bd/0x570 [ 71.561411][ C1] do_syscall_64+0xfa/0x760 [ 71.566097][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 71.572162][ C1] [ 71.574482][ C1] -> (&(&ctx->ctx_lock)->rlock){..-.} { [ 71.580028][ C1] IN-SOFTIRQ-W at: [ 71.584283][ C1] lock_acquire+0x190/0x410 [ 71.590446][ C1] _raw_spin_lock_irq+0x60/0x80 [ 71.597003][ C1] free_ioctx_users+0x2d/0x490 [ 71.603419][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 71.611750][ C1] rcu_core+0x581/0x1560 [ 71.617633][ C1] rcu_core_si+0x9/0x10 [ 71.623610][ C1] __do_softirq+0x262/0x98c [ 71.629742][ C1] irq_exit+0x19b/0x1e0 [ 71.635537][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 71.642857][ C1] apic_timer_interrupt+0xf/0x20 [ 71.649830][ C1] native_safe_halt+0xe/0x10 [ 71.656378][ C1] arch_cpu_idle+0xa/0x10 [ 71.662351][ C1] default_idle_call+0x84/0xb0 [ 71.668748][ C1] do_idle+0x3b7/0x6e0 [ 71.674446][ C1] cpu_startup_entry+0x1b/0x20 [ 71.680849][ C1] start_secondary+0x2f4/0x410 [ 71.687493][ C1] secondary_startup_64+0xa4/0xb0 [ 71.694150][ C1] INITIAL USE at: [ 71.698180][ C1] lock_acquire+0x190/0x410 [ 71.704334][ C1] _raw_spin_lock_irq+0x60/0x80 [ 71.710913][ C1] io_submit_one+0xeb5/0x2ef0 [ 71.717145][ C1] __x64_sys_io_submit+0x1bd/0x570 [ 71.723994][ C1] do_syscall_64+0xfa/0x760 [ 71.730081][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 71.737596][ C1] } [ 71.740176][ C1] ... key at: [] __key.54335+0x0/0x40 [ 71.747920][ C1] ... acquired at: [ 71.752955][ C1] mark_lock+0x517/0x1220 [ 71.757482][ C1] __lock_acquire+0x1eaf/0x4e70 [ 71.762496][ C1] lock_acquire+0x190/0x410 [ 71.767266][ C1] _raw_spin_lock_irq+0x60/0x80 [ 71.772538][ C1] free_ioctx_users+0x2d/0x490 [ 71.777485][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 71.783789][ C1] rcu_core+0x581/0x1560 [ 71.788183][ C1] rcu_core_si+0x9/0x10 [ 71.792583][ C1] __do_softirq+0x262/0x98c [ 71.797328][ C1] irq_exit+0x19b/0x1e0 [ 71.801638][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 71.807442][ C1] apic_timer_interrupt+0xf/0x20 [ 71.812542][ C1] native_safe_halt+0xe/0x10 [ 71.817300][ C1] arch_cpu_idle+0xa/0x10 [ 71.821778][ C1] default_idle_call+0x84/0xb0 [ 71.826711][ C1] do_idle+0x3b7/0x6e0 [ 71.830958][ C1] cpu_startup_entry+0x1b/0x20 [ 71.835878][ C1] start_secondary+0x2f4/0x410 [ 71.840792][ C1] secondary_startup_64+0xa4/0xb0 [ 71.846189][ C1] [ 71.848533][ C1] [ 71.848533][ C1] stack backtrace: [ 71.854500][ C1] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.3.0+ #0 [ 71.861387][ C1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 71.871551][ C1] Call Trace: [ 71.874824][ C1] [ 71.877672][ C1] dump_stack+0x172/0x1f0 [ 71.881997][ C1] print_irq_inversion_bug.part.0+0x2e4/0x2f1 [ 71.888144][ C1] check_usage_forwards.cold+0x20/0x29 [ 71.893687][ C1] ? check_usage_backwards+0x330/0x330 [ 71.899423][ C1] ? secondary_startup_64+0xa4/0xb0 [ 71.904921][ C1] mark_lock+0x517/0x1220 [ 71.909266][ C1] ? check_usage_backwards+0x330/0x330 [ 71.914716][ C1] __lock_acquire+0x1eaf/0x4e70 [ 71.919697][ C1] ? __kasan_check_read+0x11/0x20 [ 71.924828][ C1] ? mark_lock+0xc2/0x1220 [ 71.929267][ C1] ? mark_held_locks+0xf0/0xf0 [ 71.934047][ C1] lock_acquire+0x190/0x410 [ 71.938560][ C1] ? free_ioctx_users+0x2d/0x490 [ 71.943514][ C1] _raw_spin_lock_irq+0x60/0x80 [ 71.948389][ C1] ? free_ioctx_users+0x2d/0x490 [ 71.953431][ C1] free_ioctx_users+0x2d/0x490 [ 71.958176][ C1] ? rcu_dynticks_curr_cpu_in_eqs+0x54/0xb0 [ 71.964055][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 71.970192][ C1] ? percpu_ref_exit+0xd0/0xd0 [ 71.974949][ C1] rcu_core+0x581/0x1560 [ 71.979330][ C1] ? __rcu_read_unlock+0x6b0/0x6b0 [ 71.984630][ C1] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 71.990255][ C1] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 71.996222][ C1] ? run_rebalance_domains+0x227/0x2d0 [ 72.001668][ C1] rcu_core_si+0x9/0x10 [ 72.005809][ C1] __do_softirq+0x262/0x98c [ 72.010291][ C1] ? sched_clock_cpu+0x1b/0x1b0 [ 72.015218][ C1] irq_exit+0x19b/0x1e0 [ 72.019367][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 72.024897][ C1] apic_timer_interrupt+0xf/0x20 [ 72.029907][ C1] [ 72.033003][ C1] RIP: 0010:native_safe_halt+0xe/0x10 [ 72.038358][ C1] Code: f8 c1 68 fa eb 8a 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d 94 2c 64 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 84 2c 64 00 fb f4 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 e8 0e 0f 1c fa e8 59 [ 72.058311][ C1] RSP: 0018:ffff8880a98e7d68 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 [ 72.066709][ C1] RAX: 1ffffffff11e630f RBX: ffff8880a98ce340 RCX: 0000000000000000 [ 72.074665][ C1] RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880a98cebd4 [ 72.082792][ C1] RBP: ffff8880a98e7d98 R08: ffff8880a98ce340 R09: 0000000000000000 [ 72.092667][ C1] R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000 [ 72.100619][ C1] R13: ffffffff89c6a500 R14: 0000000000000000 R15: 0000000000000001 [ 72.108599][ C1] ? default_idle+0x4e/0x360 [ 72.113201][ C1] arch_cpu_idle+0xa/0x10 [ 72.117521][ C1] default_idle_call+0x84/0xb0 [ 72.122377][ C1] do_idle+0x3b7/0x6e0 [