[ 43.945761][ T26] audit: type=1800 audit(1555810366.246:26): pid=7808 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 43.967735][ T26] audit: type=1800 audit(1555810366.246:27): pid=7808 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [ 44.005119][ T26] audit: type=1800 audit(1555810366.336:28): pid=7808 uid=0 auid=4294967295 ses=4294967295 subj=_ 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. [ 44.923989][ T26] audit: type=1800 audit(1555810367.256:29): pid=7808 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="rc.local" dev="sda1" ino=2432 res=0 Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.237' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 56.595235][ T7963] ------------[ cut here ]------------ [ 56.600868][ T7963] percpu_ref_kill_and_confirm called more than once on io_ring_ctx_ref_free! [ 56.601100][ T7963] WARNING: CPU: 1 PID: 7963 at lib/percpu-refcount.c:335 percpu_ref_kill_and_confirm+0x341/0x3b0 [ 56.620348][ T7963] Kernel panic - not syncing: panic_on_warn set ... [ 56.626932][ T7963] CPU: 1 PID: 7963 Comm: syz-executor350 Not tainted 5.1.0-rc5+ #78 [ 56.634906][ T7963] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 56.644948][ T7963] Call Trace: [ 56.648324][ T7963] dump_stack+0x172/0x1f0 [ 56.652664][ T7963] ? percpu_ref_kill_and_confirm+0x340/0x3b0 [ 56.658629][ T7963] panic+0x2cb/0x65c [ 56.662511][ T7963] ? __warn_printk+0xf3/0xf3 [ 56.667087][ T7963] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 56.673067][ T7963] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 56.679407][ T7963] ? __warn.cold+0x5/0x45 [ 56.683809][ T7963] ? __warn+0xe8/0x1d0 [ 56.687999][ T7963] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 56.694005][ T7963] __warn.cold+0x20/0x45 [ 56.698252][ T7963] ? vprintk_emit+0x1ce/0x6d0 [ 56.703048][ T7963] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 56.709060][ T7963] report_bug+0x263/0x2b0 [ 56.713394][ T7963] do_error_trap+0x11b/0x200 [ 56.717986][ T7963] do_invalid_op+0x37/0x50 [ 56.722402][ T7963] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 56.728417][ T7963] invalid_op+0x14/0x20 [ 56.732579][ T7963] RIP: 0010:percpu_ref_kill_and_confirm+0x341/0x3b0 [ 56.739187][ T7963] 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 [ 56.758910][ T7963] RSP: 0018:ffff8880866bfcf0 EFLAGS: 00010082 [ 56.765543][ T7963] RAX: 0000000000000000 RBX: 0000607f5142f533 RCX: 0000000000000000 [ 56.773552][ T7963] RDX: 0000000000000000 RSI: ffffffff815afcf6 RDI: ffffed1010cd7f90 [ 56.781605][ T7963] RBP: ffff8880866bfd20 R08: ffff88808435e1c0 R09: fffffbfff1133639 [ 56.789775][ T7963] R10: fffffbfff1133638 R11: ffffffff8899b1c3 R12: ffff8880939c6c40 [ 56.798029][ T7963] R13: ffff8880939c6c48 R14: 0000000000000286 R15: 0000000000000000 [ 56.806041][ T7963] ? vprintk_func+0x86/0x189 [ 56.810851][ T7963] __io_uring_register+0xa7/0x1fe0 [ 56.816696][ T7963] ? __mutex_lock+0x3cd/0x1310 [ 56.821463][ T7963] ? __x64_sys_io_uring_register+0x182/0x1f0 [ 56.827443][ T7963] ? mutex_trylock+0x1e0/0x1e0 [ 56.832218][ T7963] ? io_sq_wq_submit_work+0x10f0/0x10f0 [ 56.837774][ T7963] ? kasan_check_write+0x14/0x20 [ 56.842706][ T7963] __x64_sys_io_uring_register+0x193/0x1f0 [ 56.848513][ T7963] do_syscall_64+0x103/0x610 [ 56.853209][ T7963] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 56.859119][ T7963] RIP: 0033:0x445eb9 [ 56.863005][ T7963] Code: e8 ac b8 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 2b 12 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 56.882605][ T7963] RSP: 002b:00007f1d300afce8 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab [ 56.891018][ T7963] RAX: ffffffffffffffda RBX: 00000000006dac38 RCX: 0000000000445eb9 [ 56.898984][ T7963] RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000003 [ 56.906959][ T7963] RBP: 00000000006dac30 R08: 00007f1d300b0700 R09: 0000000000000000 [ 56.914925][ T7963] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dac3c [ 56.922893][ T7963] R13: 00007ffe6d7b291f R14: 00007f1d300b09c0 R15: 20c49ba5e353f7cf [ 56.931610][ T7963] Kernel Offset: disabled [ 56.936024][ T7963] Rebooting in 86400 seconds..