[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 63.873296][ T26] audit: type=1800 audit(1568881606.940:25): pid=8635 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 63.924631][ T26] audit: type=1800 audit(1568881606.950:26): pid=8635 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 63.958698][ T26] audit: type=1800 audit(1568881606.950:27): pid=8635 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 '10.128.0.158' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 76.264656][ C1] [ 76.267179][ C1] ======================================================== [ 76.274516][ C1] WARNING: possible irq lock inversion dependency detected [ 76.281801][ C1] 5.3.0+ #0 Not tainted [ 76.285928][ C1] -------------------------------------------------------- [ 76.293095][ C1] swapper/1/0 just changed the state of lock: [ 76.299191][ C1] ffff88809ecc1b58 (&(&ctx->ctx_lock)->rlock){..-.}, at: free_ioctx_users+0x2d/0x490 [ 76.308644][ C1] but this lock took another, SOFTIRQ-unsafe lock in the past: [ 76.316174][ C1] (&fiq->waitq){+.+.} [ 76.316181][ C1] [ 76.316181][ C1] [ 76.316181][ C1] and interrupts could create inverse lock ordering between them. [ 76.316181][ C1] [ 76.334773][ C1] [ 76.334773][ C1] other info that might help us debug this: [ 76.343098][ C1] Possible interrupt unsafe locking scenario: [ 76.343098][ C1] [ 76.351621][ C1] CPU0 CPU1 [ 76.357169][ C1] ---- ---- [ 76.362608][ C1] lock(&fiq->waitq); [ 76.366670][ C1] local_irq_disable(); [ 76.373591][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 76.381457][ C1] lock(&fiq->waitq); [ 76.388174][ C1] [ 76.391617][ C1] lock(&(&ctx->ctx_lock)->rlock); [ 76.397044][ C1] [ 76.397044][ C1] *** DEADLOCK *** [ 76.397044][ C1] [ 76.405182][ C1] 2 locks held by swapper/1/0: [ 76.409918][ C1] #0: ffffffff88fab1c0 (rcu_callback){....}, at: rcu_core+0x60e/0x1560 [ 76.418434][ C1] #1: ffffffff88fab200 (rcu_read_lock_sched){....}, at: percpu_ref_switch_to_atomic_rcu+0x20e/0x570 [ 76.429289][ C1] [ 76.429289][ C1] the shortest dependencies between 2nd lock and 1st lock: [ 76.438763][ C1] -> (&fiq->waitq){+.+.} { [ 76.443265][ C1] HARDIRQ-ON-W at: [ 76.447320][ C1] lock_acquire+0x190/0x410 [ 76.453730][ C1] _raw_spin_lock+0x2f/0x40 [ 76.460122][ C1] flush_bg_queue+0x1f3/0x3c0 [ 76.466816][ C1] fuse_request_queue_background+0x2f8/0x5a0 [ 76.474622][ C1] fuse_request_send_background+0x58/0x110 [ 76.482347][ C1] cuse_channel_open+0x5ba/0x830 [ 76.489255][ C1] misc_open+0x395/0x4c0 [ 76.495634][ C1] chrdev_open+0x245/0x6b0 [ 76.501854][ C1] do_dentry_open+0x4df/0x1250 [ 76.508512][ C1] vfs_open+0xa0/0xd0 [ 76.515335][ C1] path_openat+0x10e9/0x4630 [ 76.521726][ C1] do_filp_open+0x1a1/0x280 [ 76.528028][ C1] do_sys_open+0x3fe/0x5d0 [ 76.534244][ C1] __x64_sys_openat+0x9d/0x100 [ 76.540894][ C1] do_syscall_64+0xfa/0x760 [ 76.547284][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 76.555392][ C1] SOFTIRQ-ON-W at: [ 76.559478][ C1] lock_acquire+0x190/0x410 [ 76.566075][ C1] _raw_spin_lock+0x2f/0x40 [ 76.572403][ C1] flush_bg_queue+0x1f3/0x3c0 [ 76.578987][ C1] fuse_request_queue_background+0x2f8/0x5a0 [ 76.587286][ C1] fuse_request_send_background+0x58/0x110 [ 76.595171][ C1] cuse_channel_open+0x5ba/0x830 [ 76.601922][ C1] misc_open+0x395/0x4c0 [ 76.607976][ C1] chrdev_open+0x245/0x6b0 [ 76.614282][ C1] do_dentry_open+0x4df/0x1250 [ 76.620849][ C1] vfs_open+0xa0/0xd0 [ 76.626839][ C1] path_openat+0x10e9/0x4630 [ 76.633226][ C1] do_filp_open+0x1a1/0x280 [ 76.639629][ C1] do_sys_open+0x3fe/0x5d0 [ 76.645867][ C1] __x64_sys_openat+0x9d/0x100 [ 76.652695][ C1] do_syscall_64+0xfa/0x760 [ 76.659101][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 76.666968][ C1] INITIAL USE at: [ 76.671115][ C1] lock_acquire+0x190/0x410 [ 76.677385][ C1] _raw_spin_lock+0x2f/0x40 [ 76.683795][ C1] flush_bg_queue+0x1f3/0x3c0 [ 76.690279][ C1] fuse_request_queue_background+0x2f8/0x5a0 [ 76.698066][ C1] fuse_request_send_background+0x58/0x110 [ 76.705626][ C1] cuse_channel_open+0x5ba/0x830 [ 76.712874][ C1] misc_open+0x395/0x4c0 [ 76.718922][ C1] chrdev_open+0x245/0x6b0 [ 76.725164][ C1] do_dentry_open+0x4df/0x1250 [ 76.731990][ C1] vfs_open+0xa0/0xd0 [ 76.737982][ C1] path_openat+0x10e9/0x4630 [ 76.744788][ C1] do_filp_open+0x1a1/0x280 [ 76.751282][ C1] do_sys_open+0x3fe/0x5d0 [ 76.757426][ C1] __x64_sys_openat+0x9d/0x100 [ 76.763913][ C1] do_syscall_64+0xfa/0x760 [ 76.770139][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 76.778199][ C1] } [ 76.780779][ C1] ... key at: [] __key.44699+0x0/0x40 [ 76.788403][ C1] ... acquired at: [ 76.792985][ C1] _raw_spin_lock+0x2f/0x40 [ 76.797655][ C1] io_submit_one+0xefa/0x2ef0 [ 76.802537][ C1] __x64_sys_io_submit+0x1bd/0x570 [ 76.808292][ C1] do_syscall_64+0xfa/0x760 [ 76.813231][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 76.821019][ C1] [ 76.824065][ C1] -> (&(&ctx->ctx_lock)->rlock){..-.} { [ 76.830190][ C1] IN-SOFTIRQ-W at: [ 76.834337][ C1] lock_acquire+0x190/0x410 [ 76.840899][ C1] _raw_spin_lock_irq+0x60/0x80 [ 76.847919][ C1] free_ioctx_users+0x2d/0x490 [ 76.854618][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 76.862736][ C1] rcu_core+0x581/0x1560 [ 76.868616][ C1] rcu_core_si+0x9/0x10 [ 76.874985][ C1] __do_softirq+0x262/0x98c [ 76.881253][ C1] irq_exit+0x19b/0x1e0 [ 76.887233][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 76.894874][ C1] apic_timer_interrupt+0xf/0x20 [ 76.901825][ C1] native_safe_halt+0xe/0x10 [ 76.908248][ C1] arch_cpu_idle+0xa/0x10 [ 76.914215][ C1] default_idle_call+0x84/0xb0 [ 76.920806][ C1] do_idle+0x3b7/0x6e0 [ 76.926514][ C1] cpu_startup_entry+0x1b/0x20 [ 76.933001][ C1] start_secondary+0x2f4/0x410 [ 76.939603][ C1] secondary_startup_64+0xa4/0xb0 [ 76.946536][ C1] INITIAL USE at: [ 76.950440][ C1] lock_acquire+0x190/0x410 [ 76.956493][ C1] _raw_spin_lock_irq+0x60/0x80 [ 76.963594][ C1] io_submit_one+0xeb5/0x2ef0 [ 76.970222][ C1] __x64_sys_io_submit+0x1bd/0x570 [ 76.977033][ C1] do_syscall_64+0xfa/0x760 [ 76.983349][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 76.991098][ C1] } [ 76.993651][ C1] ... key at: [] __key.54326+0x0/0x40 [ 77.001302][ C1] ... acquired at: [ 77.005108][ C1] mark_lock+0x517/0x1220 [ 77.009741][ C1] __lock_acquire+0x1eaf/0x4e70 [ 77.014836][ C1] lock_acquire+0x190/0x410 [ 77.019588][ C1] _raw_spin_lock_irq+0x60/0x80 [ 77.024764][ C1] free_ioctx_users+0x2d/0x490 [ 77.029700][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 77.036048][ C1] rcu_core+0x581/0x1560 [ 77.040796][ C1] rcu_core_si+0x9/0x10 [ 77.045283][ C1] __do_softirq+0x262/0x98c [ 77.049959][ C1] irq_exit+0x19b/0x1e0 [ 77.054417][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 77.060329][ C1] apic_timer_interrupt+0xf/0x20 [ 77.065529][ C1] native_safe_halt+0xe/0x10 [ 77.070324][ C1] arch_cpu_idle+0xa/0x10 [ 77.074902][ C1] default_idle_call+0x84/0xb0 [ 77.079831][ C1] do_idle+0x3b7/0x6e0 [ 77.084137][ C1] cpu_startup_entry+0x1b/0x20 [ 77.089431][ C1] start_secondary+0x2f4/0x410 [ 77.094527][ C1] secondary_startup_64+0xa4/0xb0 [ 77.099946][ C1] [ 77.102264][ C1] [ 77.102264][ C1] stack backtrace: [ 77.108390][ C1] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.3.0+ #0 [ 77.115305][ C1] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 77.125360][ C1] Call Trace: [ 77.128813][ C1] [ 77.131741][ C1] dump_stack+0x172/0x1f0 [ 77.136089][ C1] print_irq_inversion_bug.part.0+0x2e4/0x2f1 [ 77.142457][ C1] check_usage_forwards.cold+0x20/0x29 [ 77.148682][ C1] ? check_usage_backwards+0x330/0x330 [ 77.154489][ C1] ? secondary_startup_64+0xa4/0xb0 [ 77.159773][ C1] mark_lock+0x517/0x1220 [ 77.164723][ C1] ? check_usage_backwards+0x330/0x330 [ 77.170292][ C1] __lock_acquire+0x1eaf/0x4e70 [ 77.175224][ C1] ? __kasan_check_read+0x11/0x20 [ 77.180456][ C1] ? mark_lock+0xc2/0x1220 [ 77.185544][ C1] ? mark_held_locks+0xf0/0xf0 [ 77.190570][ C1] lock_acquire+0x190/0x410 [ 77.196234][ C1] ? free_ioctx_users+0x2d/0x490 [ 77.201477][ C1] _raw_spin_lock_irq+0x60/0x80 [ 77.206421][ C1] ? free_ioctx_users+0x2d/0x490 [ 77.211518][ C1] free_ioctx_users+0x2d/0x490 [ 77.216648][ C1] ? rcu_dynticks_curr_cpu_in_eqs+0x54/0xb0 [ 77.222848][ C1] percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 [ 77.230559][ C1] ? percpu_ref_exit+0xd0/0xd0 [ 77.235379][ C1] rcu_core+0x581/0x1560 [ 77.239633][ C1] ? __rcu_read_unlock+0x6b0/0x6b0 [ 77.245682][ C1] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 77.251506][ C1] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 77.258456][ C1] ? run_rebalance_domains+0x227/0x2d0 [ 77.264869][ C1] rcu_core_si+0x9/0x10 [ 77.269097][ C1] __do_softirq+0x262/0x98c [ 77.273715][ C1] ? sched_clock_cpu+0x1b/0x1b0 [ 77.278996][ C1] irq_exit+0x19b/0x1e0 [ 77.283591][ C1] smp_apic_timer_interrupt+0x1a3/0x610 [ 77.289255][ C1] apic_timer_interrupt+0xf/0x20 [ 77.294185][ C1] [ 77.297118][ C1] RIP: 0010:native_safe_halt+0xe/0x10 [ 77.302486][ C1] Code: d8 cf 6a fa eb 8a 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d 94 6c 66 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 84 6c 66 00 fb f4 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 e8 ae 4e 1e fa e8 59 [ 77.324163][ C1] RSP: 0018:ffff8880a98e7d68 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 [ 77.332989][ C1] RAX: 1ffffffff11e630f RBX: ffff8880a98d8340 RCX: 0000000000000000 [ 77.342195][ C1] RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880a98d8bd4 [ 77.350351][ C1] RBP: ffff8880a98e7d98 R08: ffff8880a98d8340 R09: 0000000000000000 [ 77.358792][ C1] R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000 [ 77.366837][ C1] R13: ffffffff89c64d00 R14: 0000000000000000 R15: 0000000000000001 [ 77.376042][ C1] ? default_idle+0x4e/0x360 [ 77.380623][ C1] arch_cpu_idle+0xa/0x10 [ 77.385121][ C1] default_idle_call+0x84/0xb0 [ 77.390062][ C1] do_idle+0x3b7/0x6e0 [ 77.394237][ C1] ? arch_cpu_idle_exit+0x80/0x80 [ 77.399347][ C1] ? _raw_spin_unlock_irqrestore+0xa4/0xe0 [ 77.405352][ C1] ? complete+0x61/0x80 [ 77.409899][ C1] cpu_startup_entry+0x1b/0x20 [ 77.414983][ C1] start_secondary+0x2f4/0x410 [ 77.419827][ C1] ? set_cpu_sibling_map+0x2180/0x2180 [ 77.425600][ C1] secondary_startup_64+0xa4/0xb0