[ 40.024048][ T27] audit: type=1800 audit(1555819427.958:25): pid=7729 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 40.059926][ T27] audit: type=1800 audit(1555819427.958:26): pid=7729 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 40.093647][ T27] audit: type=1800 audit(1555819427.958:27): pid=7729 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 40.115534][ T27] audit: type=1800 audit(1555819427.958:28): pid=7729 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="ssh" dev="sda1" ino=2417 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 '10.128.0.138' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 49.259985][ T7883] ------------[ cut here ]------------ [ 49.265576][ T7883] percpu_ref_kill_and_confirm called more than once on io_ring_ctx_ref_free! [ 49.265779][ T7883] WARNING: CPU: 1 PID: 7883 at lib/percpu-refcount.c:335 percpu_ref_kill_and_confirm+0x341/0x3b0 [ 49.284991][ T7883] Kernel panic - not syncing: panic_on_warn set ... [ 49.291558][ T7883] CPU: 1 PID: 7883 Comm: syz-executor389 Not tainted 5.1.0-rc5+ #78 [ 49.299543][ T7883] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 49.309576][ T7883] Call Trace: [ 49.312867][ T7883] dump_stack+0x172/0x1f0 [ 49.317273][ T7883] ? percpu_ref_kill_and_confirm+0x340/0x3b0 [ 49.323238][ T7883] panic+0x2cb/0x65c [ 49.327137][ T7883] ? __warn_printk+0xf3/0xf3 [ 49.331715][ T7883] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 49.337676][ T7883] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 49.343903][ T7883] ? __warn.cold+0x5/0x45 [ 49.348221][ T7883] ? __warn+0xe8/0x1d0 [ 49.352306][ T7883] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 49.358278][ T7883] __warn.cold+0x20/0x45 [ 49.362520][ T7883] ? vprintk_emit+0x1ce/0x6d0 [ 49.367195][ T7883] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 49.373161][ T7883] report_bug+0x263/0x2b0 [ 49.377478][ T7883] do_error_trap+0x11b/0x200 [ 49.382074][ T7883] do_invalid_op+0x37/0x50 [ 49.386510][ T7883] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 49.392508][ T7883] invalid_op+0x14/0x20 [ 49.396645][ T7883] RIP: 0010:percpu_ref_kill_and_confirm+0x341/0x3b0 [ 49.403214][ T7883] Code: 42 e0 2a 06 01 48 89 fa 48 c1 ea 03 80 3c 02 00 75 76 49 8b 54 24 10 48 c7 c6 a0 71 a1 87 48 c7 c7 40 71 a1 87 e8 ad 92 13 fe <0f> 0b 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 80 3c 02 [ 49.422797][ T7883] RSP: 0018:ffff8880a8e77cf0 EFLAGS: 00010082 [ 49.428843][ T7883] RAX: 0000000000000000 RBX: 0000607f5142e3cb RCX: 0000000000000000 [ 49.436793][ T7883] RDX: 0000000000000000 RSI: ffffffff815afcf6 RDI: ffffed10151cef90 [ 49.444746][ T7883] RBP: ffff8880a8e77d20 R08: ffff8880a87541c0 R09: fffffbfff1133639 [ 49.452698][ T7883] R10: fffffbfff1133638 R11: ffffffff8899b1c3 R12: ffff8880a8aa2100 [ 49.460652][ T7883] R13: ffff8880a8aa2108 R14: 0000000000000286 R15: 0000000000000000 [ 49.468621][ T7883] ? vprintk_func+0x86/0x189 [ 49.473212][ T7883] __io_uring_register+0xa7/0x1fe0 [ 49.478310][ T7883] ? __mutex_lock+0x3cd/0x1310 [ 49.483053][ T7883] ? __x64_sys_io_uring_register+0x182/0x1f0 [ 49.489017][ T7883] ? mutex_trylock+0x1e0/0x1e0 [ 49.493763][ T7883] ? io_sq_wq_submit_work+0x10f0/0x10f0 [ 49.499292][ T7883] ? kasan_check_write+0x14/0x20 [ 49.504215][ T7883] __x64_sys_io_uring_register+0x193/0x1f0 [ 49.510007][ T7883] do_syscall_64+0x103/0x610 [ 49.514670][ T7883] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 49.520557][ T7883] RIP: 0033:0x445989 [ 49.524620][ T7883] Code: e8 ec bc 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb 11 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 49.544312][ T7883] RSP: 002b:00007feeacf57db8 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab [ 49.552710][ T7883] RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 0000000000445989 [ 49.560665][ T7883] RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000003 [ 49.568620][ T7883] RBP: 00000000006dbc30 R08: 00007feeacf58700 R09: 0000000000000000 [ 49.576583][ T7883] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c [ 49.584534][ T7883] R13: 00007ffce9ed599f R14: 00007feeacf589c0 R15: 0000000000000002 [ 49.593327][ T7883] Kernel Offset: disabled [ 49.597718][ T7883] Rebooting in 86400 seconds..