[ 37.656757][ T26] audit: type=1800 audit(1555805703.451:27): pid=7547 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 37.682116][ T26] audit: type=1800 audit(1555805703.461:28): pid=7547 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. [ 38.194803][ T26] audit: type=1800 audit(1555805704.051:29): pid=7547 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="rc.local" dev="sda1" ino=2432 res=0 [ 38.215237][ T26] audit: type=1800 audit(1555805704.051:30): pid=7547 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="rmnologin" dev="sda1" ino=2423 res=0 Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.1.62' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 53.160812][ T7703] ------------[ cut here ]------------ [ 53.166411][ T7703] percpu_ref_kill_and_confirm called more than once on io_ring_ctx_ref_free! [ 53.166611][ T7703] WARNING: CPU: 0 PID: 7703 at lib/percpu-refcount.c:335 percpu_ref_kill_and_confirm+0x341/0x3b0 [ 53.185854][ T7703] Kernel panic - not syncing: panic_on_warn set ... [ 53.192458][ T7703] CPU: 0 PID: 7703 Comm: syz-executor557 Not tainted 5.1.0-rc5+ #78 [ 53.200447][ T7703] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 53.210569][ T7703] Call Trace: [ 53.213844][ T7703] dump_stack+0x172/0x1f0 [ 53.218158][ T7703] ? percpu_ref_kill_and_confirm+0x340/0x3b0 [ 53.224117][ T7703] panic+0x2cb/0x65c [ 53.227992][ T7703] ? __warn_printk+0xf3/0xf3 [ 53.232569][ T7703] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 53.238530][ T7703] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 53.244747][ T7703] ? __warn.cold+0x5/0x45 [ 53.249054][ T7703] ? __warn+0xe8/0x1d0 [ 53.253110][ T7703] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 53.259072][ T7703] __warn.cold+0x20/0x45 [ 53.263296][ T7703] ? vprintk_emit+0x1ce/0x6d0 [ 53.267953][ T7703] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 53.273912][ T7703] report_bug+0x263/0x2b0 [ 53.278222][ T7703] do_error_trap+0x11b/0x200 [ 53.282797][ T7703] do_invalid_op+0x37/0x50 [ 53.287200][ T7703] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 53.293162][ T7703] invalid_op+0x14/0x20 [ 53.297298][ T7703] RIP: 0010:percpu_ref_kill_and_confirm+0x341/0x3b0 [ 53.303941][ T7703] 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 [ 53.323527][ T7703] RSP: 0018:ffff888098017cf0 EFLAGS: 00010082 [ 53.329570][ T7703] RAX: 0000000000000000 RBX: 0000607f5142f723 RCX: 0000000000000000 [ 53.337520][ T7703] RDX: 0000000000000000 RSI: ffffffff815afcf6 RDI: ffffed1013002f90 [ 53.345475][ T7703] RBP: ffff888098017d20 R08: ffff88808f2445c0 R09: fffffbfff1133639 [ 53.353429][ T7703] R10: fffffbfff1133638 R11: ffffffff8899b1c3 R12: ffff8880967253c0 [ 53.361382][ T7703] R13: ffff8880967253c8 R14: 0000000000000286 R15: 0000000000000000 [ 53.369359][ T7703] ? vprintk_func+0x86/0x189 [ 53.373939][ T7703] __io_uring_register+0xa7/0x1fe0 [ 53.379033][ T7703] ? __mutex_lock+0x3cd/0x1310 [ 53.383814][ T7703] ? __x64_sys_io_uring_register+0x182/0x1f0 [ 53.389872][ T7703] ? mutex_trylock+0x1e0/0x1e0 [ 53.394622][ T7703] ? io_sq_wq_submit_work+0x10f0/0x10f0 [ 53.400207][ T7703] ? kasan_check_write+0x14/0x20 [ 53.405132][ T7703] __x64_sys_io_uring_register+0x193/0x1f0 [ 53.410934][ T7703] do_syscall_64+0x103/0x610 [ 53.415512][ T7703] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 53.421385][ T7703] RIP: 0033:0x4467c9 [ 53.425264][ T7703] Code: e8 5c b3 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 0b 08 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 53.444850][ T7703] RSP: 002b:00007f3ed9a5edb8 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab [ 53.453288][ T7703] RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 00000000004467c9 [ 53.461242][ T7703] RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000003 [ 53.469227][ T7703] RBP: 00000000006dbc30 R08: 00007f3ed9a5f700 R09: 0000000000000000 [ 53.477216][ T7703] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c [ 53.485208][ T7703] R13: 00007ffd0f7ce15f R14: 00007f3ed9a5f9c0 R15: 20c49ba5e353f7cf [ 53.493993][ T7703] Kernel Offset: disabled [ 53.498385][ T7703] Rebooting in 86400 seconds..