[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 60.249150][ T26] audit: type=1800 audit(1569003528.542:25): pid=8924 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 60.278368][ T26] audit: type=1800 audit(1569003528.542:26): pid=8924 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 60.338394][ T26] audit: type=1800 audit(1569003528.552:27): pid=8924 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 '10.128.0.109' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 70.818474][ C1] [ 70.821036][ C1] ======================================================== [ 70.828222][ C1] WARNING: possible irq lock inversion dependency detected [ 70.835405][ C1] 5.3.0+ #0 Not tainted [ 70.839619][ C1] -------------------------------------------------------- [ 70.846878][ C1] swapper/1/0 just changed the state of lock: [ 70.852934][ C1] ffff8880a0eb1b58 (&(&ctx->ctx_lock)->rlock){..-.}, at: free_ioctx_users+0x2d/0x490 [ 70.862393][ C1] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 70.869923][ C1] (&fiq->waitq){+.+.} [ 70.869929][ C1] [ 70.869929][ C1] [ 70.869929][ C1] and interrupts could create inverse lock ordering between them. [ 70.869929][ C1] [ 70.888374][ C1] [ 70.888374][ C1] other info that might help us debug this: [ 70.896733][ C1] Possible interrupt unsafe locking scenario: [ 70.896733][ C1] [ 70.905110][ C1] CPU0 CPU1 [ 70.910453][ C1] ---- ---- [ 70.915791][ C1] lock(&fiq->waitq); [ 70.919836][ C1] local_irq_disable(); [ 70.926737][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 70.934518][ C1] lock(&fiq->waitq); [ 70.941160][ C1] [ 70.944622][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 70.949976][ C1] [ 70.949976][ C1] *** DEADLOCK *** [ 70.949976][ C1] [ 70.958630][ C1] 2 locks held by swapper/1/0: [ 70.963376][ C1] #0: ffffffff88fab1c0 (rcu_callback){....}, at: rcu_core+0x60e/0x1560 [ 70.971695][ C1] #1: ffffffff88fab200 (rcu_read_lock_sched){....}, at: percpu_ref_switch_to_atomic_rcu+0x20e/0x570 [ 70.982539][ C1] [ 70.982539][ C1] the shortest dependencies between 2nd lock and 1st lock: [ 70.991881][ C1] -> (&fiq->waitq){+.+.} { [ 70.996386][ C1] HARDIRQ-ON-W at: [ 71.000437][ C1] lock_acquire+0x190/0x410 [ 71.006748][ C1] _raw_spin_lock+0x2f/0x40 [ 71.013072][ C1] flush_bg_queue+0x1f3/0x3c0 [ 71.019543][ C1] fuse_request_queue_background+0x2f8/0x5a0 [ 71.027315][ C1] fuse_request_send_background+0x58/0x110 [ 71.034930][ C1] cuse_channel_open+0x5ba/0x830 [ 71.041850][ C1] misc_open+0x395/0x4c0 [ 71.047908][ C1] chrdev_open+0x245/0x6b0 [ 71.054244][ C1] do_dentry_open+0x4df/0x1250 [ 71.060817][ C1] vfs_open+0xa0/0xd0 [ 71.067154][ C1] path_openat+0x10e9/0x4630 [ 71.073823][ C1] do_filp_open+0x1a1/0x280 [ 71.080914][ C1] do_sys_open+0x3fe/0x5d0 [ 71.087126][ C1] __ia32_compat_sys_openat+0x98/0xf0 [ 71.094340][ C1] do_fast_syscall_32+0x27b/0xdb3 [ 71.101164][ C1] entry_SYSENTER_compat+0x70/0x7f [ 71.108069][ C1] SOFTIRQ-ON-W at: [ 71.112169][ C1] lock_acquire+0x190/0x410 [ 71.118471][ C1] _raw_spin_lock+0x2f/0x40 [ 71.124775][ C1] flush_bg_queue+0x1f3/0x3c0 [ 71.131253][ C1] fuse_request_queue_background+0x2f8/0x5a0 [ 71.139045][ C1] fuse_request_send_background+0x58/0x110 [ 71.146649][ C1] cuse_channel_open+0x5ba/0x830 [ 71.153491][ C1] misc_open+0x395/0x4c0 [ 71.159535][ C1] chrdev_open+0x245/0x6b0 [ 71.165840][ C1] do_dentry_open+0x4df/0x1250 [ 71.173370][ C1] vfs_open+0xa0/0xd0 [ 71.179416][ C1] path_openat+0x10e9/0x4630 [ 71.185803][ C1] do_filp_open+0x1a1/0x280 [ 71.192163][ C1] do_sys_open+0x3fe/0x5d0 [ 71.198444][ C1] __ia32_compat_sys_openat+0x98/0xf0 [ 71.205643][ C1] do_fast_syscall_32+0x27b/0xdb3 [ 71.212874][ C1] entry_SYSENTER_compat+0x70/0x7f [ 71.219957][ C1] INITIAL USE at: [ 71.223937][ C1] lock_acquire+0x190/0x410 [ 71.230203][ C1] _raw_spin_lock+0x2f/0x40 [ 71.236425][ C1] flush_bg_queue+0x1f3/0x3c0 [ 71.242998][ C1] fuse_request_queue_background+0x2f8/0x5a0 [ 71.250707][ C1] fuse_request_send_background+0x58/0x110 [ 71.258234][ C1] cuse_channel_open+0x5ba/0x830 [ 71.264897][ C1] misc_open+0x395/0x4c0 [ 71.270852][ C1] chrdev_open+0x245/0x6b0 [ 71.277200][ C1] do_dentry_open+0x4df/0x1250 [ 71.283679][ C1] vfs_open+0xa0/0xd0 [ 71.289380][ C1] path_openat+0x10e9/0x4630 [ 71.295692][ C1] do_filp_open+0x1a1/0x280 [ 71.301910][ C1] do_sys_open+0x3fe/0x5d0 [ 71.308053][ C1] __ia32_compat_sys_openat+0x98/0xf0 [ 71.315140][ C1] do_fast_syscall_32+0x27b/0xdb3 [ 71.321905][ C1] entry_SYSENTER_compat+0x70/0x7f [ 71.328726][ C1] } [ 71.331304][ C1] ... key at: [] __key.44708+0x0/0x40 [ 71.338831][ C1] ... acquired at: [ 71.342717][ C1] _raw_spin_lock+0x2f/0x40 [ 71.347371][ C1] io_submit_one+0xefa/0x2ef0 [ 71.352196][ C1] __ia32_compat_sys_io_submit+0x1bf/0x570 [ 71.358241][ C1] do_fast_syscall_32+0x27b/0xdb3 [ 71.363515][ C1] entry_SYSENTER_compat+0x70/0x7f [ 71.368771][ C1] [ 71.371087][ C1] -> (&(&ctx->ctx_lock)->rlock){..-.} { [ 71.376607][ C1] IN-SOFTIRQ-W at: [ 71.380568][ C1] lock_acquire+0x190/0x410 [ 71.386708][ C1] _raw_spin_lock_irq+0x60/0x80 [ 71.393192][ C1] free_ioctx_users+0x2d/0x490 [ 71.399597][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 71.407372][ C1] rcu_core+0x581/0x1560 [ 71.413239][ C1] rcu_core_si+0x9/0x10 [ 71.419596][ C1] __do_softirq+0x262/0x98c [ 71.425807][ C1] irq_exit+0x19b/0x1e0 [ 71.431690][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 71.438870][ C1] apic_timer_interrupt+0xf/0x20 [ 71.445430][ C1] native_safe_halt+0xe/0x10 [ 71.451733][ C1] arch_cpu_idle+0xa/0x10 [ 71.457708][ C1] default_idle_call+0x84/0xb0 [ 71.464100][ C1] do_idle+0x3b7/0x6e0 [ 71.469862][ C1] cpu_startup_entry+0x1b/0x20 [ 71.476290][ C1] start_secondary+0x2f4/0x410 [ 71.482697][ C1] secondary_startup_64+0xa4/0xb0 [ 71.489446][ C1] INITIAL USE at: [ 71.493324][ C1] lock_acquire+0x190/0x410 [ 71.499554][ C1] _raw_spin_lock_irq+0x60/0x80 [ 71.506420][ C1] io_submit_one+0xeb5/0x2ef0 [ 71.512789][ C1] __ia32_compat_sys_io_submit+0x1bf/0x570 [ 71.520142][ C1] do_fast_syscall_32+0x27b/0xdb3 [ 71.526906][ C1] entry_SYSENTER_compat+0x70/0x7f [ 71.533678][ C1] } [ 71.536256][ C1] ... key at: [] __key.54335+0x0/0x40 [ 71.543679][ C1] ... acquired at: [ 71.547467][ C1] mark_lock+0x517/0x1220 [ 71.552057][ C1] __lock_acquire+0x1eaf/0x4e70 [ 71.557086][ C1] lock_acquire+0x190/0x410 [ 71.561838][ C1] _raw_spin_lock_irq+0x60/0x80 [ 71.566849][ C1] free_ioctx_users+0x2d/0x490 [ 71.571764][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 71.578124][ C1] rcu_core+0x581/0x1560 [ 71.582583][ C1] rcu_core_si+0x9/0x10 [ 71.587190][ C1] __do_softirq+0x262/0x98c [ 71.592007][ C1] irq_exit+0x19b/0x1e0 [ 71.596484][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 71.602196][ C1] apic_timer_interrupt+0xf/0x20 [ 71.607286][ C1] native_safe_halt+0xe/0x10 [ 71.612058][ C1] arch_cpu_idle+0xa/0x10 [ 71.616539][ C1] default_idle_call+0x84/0xb0 [ 71.622767][ C1] do_idle+0x3b7/0x6e0 [ 71.626999][ C1] cpu_startup_entry+0x1b/0x20 [ 71.631919][ C1] start_secondary+0x2f4/0x410 [ 71.636831][ C1] secondary_startup_64+0xa4/0xb0 [ 71.642025][ C1] [ 71.645286][ C1] [ 71.645286][ C1] stack backtrace: [ 71.651765][ C1] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.3.0+ #0 [ 71.658515][ C1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 71.668546][ C1] Call Trace: [ 71.671828][ C1] [ 71.674663][ C1] dump_stack+0x172/0x1f0 [ 71.679668][ C1] print_irq_inversion_bug.part.0+0x2e4/0x2f1 [ 71.685724][ C1] check_usage_forwards.cold+0x20/0x29 [ 71.691174][ C1] ? check_usage_backwards+0x330/0x330 [ 71.696628][ C1] ? secondary_startup_64+0xa4/0xb0 [ 71.701912][ C1] mark_lock+0x517/0x1220 [ 71.706232][ C1] ? check_usage_backwards+0x330/0x330 [ 71.711786][ C1] __lock_acquire+0x1eaf/0x4e70 [ 71.716615][ C1] ? __kasan_check_read+0x11/0x20 [ 71.721619][ C1] ? mark_lock+0xc2/0x1220 [ 71.726100][ C1] ? mark_held_locks+0xf0/0xf0 [ 71.730858][ C1] lock_acquire+0x190/0x410 [ 71.735352][ C1] ? free_ioctx_users+0x2d/0x490 [ 71.740298][ C1] _raw_spin_lock_irq+0x60/0x80 [ 71.745122][ C1] ? free_ioctx_users+0x2d/0x490 [ 71.750035][ C1] free_ioctx_users+0x2d/0x490 [ 71.754783][ C1] ? rcu_dynticks_curr_cpu_in_eqs+0x54/0xb0 [ 71.760742][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 71.766973][ C1] ? percpu_ref_exit+0xd0/0xd0 [ 71.771800][ C1] rcu_core+0x581/0x1560 [ 71.776974][ C1] ? __rcu_read_unlock+0x6b0/0x6b0 [ 71.782160][ C1] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 71.787698][ C1] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 71.793659][ C1] ? run_rebalance_domains+0x227/0x2d0 [ 71.799195][ C1] rcu_core_si+0x9/0x10 [ 71.803332][ C1] __do_softirq+0x262/0x98c [ 71.807822][ C1] ? sched_clock_cpu+0x1b/0x1b0 [ 71.812671][ C1] irq_exit+0x19b/0x1e0 [ 71.816827][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 71.822467][ C1] apic_timer_interrupt+0xf/0x20 [ 71.827404][ C1] [ 71.830327][ C1] RIP: 0010:native_safe_halt+0xe/0x10 [ 71.835681][ C1] Code: d8 ed 68 fa eb 8a 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d 94 7c 64 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 84 7c 64 00 fb f4 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 e8 ae 5e 1c fa e8 59 [ 71.855264][ C1] RSP: 0018:ffff8880a98e7d68 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 [ 71.863665][ C1] RAX: 1ffffffff11e630f RBX: ffff8880a98ce340 RCX: 0000000000000000 [ 71.871912][ C1] RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880a98cebd4 [ 71.879883][ C1] RBP: ffff8880a98e7d98 R08: ffff8880a98ce340 R09: 0000000000000000 [ 71.887861][ C1] R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000 [ 71.895848][ C1] R13: ffffffff89c6a100 R14: 0000000000000000 R15: 0000000000000001 [ 71.903836][ C1] ? default_idle+0x4e/0x360 [ 71.908420][ C1] arch_cpu_idle+0xa/0x10 [ 71.912730][ C1] default_idle_call+0x84/0xb0 [ 71.917506][ C1] do_idle+0x3b7/0x6e0 [ 71.921555][ C1