[ 34.499307][ T26] audit: type=1800 audit(1555811174.024:27): pid=7395 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 34.538157][ T26] audit: type=1800 audit(1555811174.024:28): pid=7395 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. [ 35.312254][ T26] audit: type=1800 audit(1555811174.904:29): pid=7395 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 [ 35.333346][ T26] audit: type=1800 audit(1555811174.904:30): pid=7395 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 '10.128.15.198' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 45.019918][ T7550] ------------[ cut here ]------------ [ 45.025739][ T7550] percpu_ref_kill_and_confirm called more than once on io_ring_ctx_ref_free! [ 45.025971][ T7550] WARNING: CPU: 0 PID: 7550 at lib/percpu-refcount.c:335 percpu_ref_kill_and_confirm+0x341/0x3b0 [ 45.046630][ T7550] Kernel panic - not syncing: panic_on_warn set ... [ 45.053343][ T7550] CPU: 0 PID: 7550 Comm: syz-executor277 Not tainted 5.1.0-rc5+ #77 [ 45.062464][ T7550] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 45.073041][ T7550] Call Trace: [ 45.076493][ T7550] dump_stack+0x172/0x1f0 [ 45.080940][ T7550] ? percpu_ref_kill_and_confirm+0x340/0x3b0 [ 45.086916][ T7550] panic+0x2cb/0x65c [ 45.091162][ T7550] ? __warn_printk+0xf3/0xf3 [ 45.095889][ T7550] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 45.102406][ T7550] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 45.109013][ T7550] ? __warn.cold+0x5/0x45 [ 45.113335][ T7550] ? __warn+0xe8/0x1d0 [ 45.117408][ T7550] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 45.123663][ T7550] __warn.cold+0x20/0x45 [ 45.128195][ T7550] ? vprintk_emit+0x1ce/0x6d0 [ 45.132888][ T7550] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 45.139215][ T7550] report_bug+0x263/0x2b0 [ 45.143952][ T7550] do_error_trap+0x11b/0x200 [ 45.149003][ T7550] do_invalid_op+0x37/0x50 [ 45.153435][ T7550] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 45.159745][ T7550] invalid_op+0x14/0x20 [ 45.164380][ T7550] RIP: 0010:percpu_ref_kill_and_confirm+0x341/0x3b0 [ 45.171733][ T7550] 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 [ 45.191343][ T7550] RSP: 0018:ffff888090b67ce0 EFLAGS: 00010086 [ 45.197576][ T7550] RAX: 0000000000000000 RBX: 0000607f5142d66b RCX: 0000000000000000 [ 45.205544][ T7550] RDX: 0000000000000000 RSI: ffffffff815afcf6 RDI: ffffed101216cf8e [ 45.213524][ T7550] RBP: ffff888090b67d10 R08: ffff888091252640 R09: fffffbfff1133639 [ 45.221495][ T7550] R10: fffffbfff1133638 R11: ffffffff8899b1c3 R12: ffff888093e3ebc0 [ 45.229450][ T7550] R13: ffff888093e3ebc8 R14: 0000000000000286 R15: 0000000000000000 [ 45.237426][ T7550] ? vprintk_func+0x86/0x189 [ 45.242108][ T7550] __io_uring_register+0xa7/0x1fe0 [ 45.247561][ T7550] ? __mutex_lock+0x3cd/0x1310 [ 45.252322][ T7550] ? __ia32_sys_io_uring_register+0x182/0x1f0 [ 45.258575][ T7550] ? mutex_trylock+0x1e0/0x1e0 [ 45.263359][ T7550] ? io_sq_wq_submit_work+0x10f0/0x10f0 [ 45.268898][ T7550] ? calculate_sigpending+0x87/0xa0 [ 45.274535][ T7550] __ia32_sys_io_uring_register+0x193/0x1f0 [ 45.282135][ T7550] do_fast_syscall_32+0x281/0xc98 [ 45.287448][ T7550] entry_SYSENTER_compat+0x70/0x7f [ 45.292547][ T7550] RIP: 0023:0xf7f2f869 [ 45.296687][ T7550] Code: 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 14 24 c3 8b 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90 [ 45.316566][ T7550] RSP: 002b:00000000f7f0a1ec EFLAGS: 00000296 ORIG_RAX: 00000000000001ab [ 45.325301][ T7550] RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000000001 [ 45.335241][ T7550] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 45.343805][ T7550] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [ 45.352165][ T7550] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 45.366039][ T7550] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 [ 45.375966][ T7550] Kernel Offset: disabled [ 45.380470][ T7550] Rebooting in 86400 seconds..