[ 41.393851][ T26] audit: type=1800 audit(1555811279.517:25): pid=7766 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 41.427996][ T26] audit: type=1800 audit(1555811279.517:26): pid=7766 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 41.458371][ T26] audit: type=1800 audit(1555811279.527:27): pid=7766 uid=0 auid=4294967295 ses=4294967295 subj=_ 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. [....] startpar: service(s) returned failure: ssh ...[?25l[?1c7[FAIL8[?25h[?0c failed! Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.0.17' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 52.445097][ T7943] ------------[ cut here ]------------ [ 52.450721][ T7943] percpu_ref_kill_and_confirm called more than once on io_ring_ctx_ref_free! [ 52.451056][ T7943] WARNING: CPU: 1 PID: 7943 at lib/percpu-refcount.c:335 percpu_ref_kill_and_confirm+0x341/0x3b0 [ 52.470297][ T7943] Kernel panic - not syncing: panic_on_warn set ... [ 52.476880][ T7943] CPU: 1 PID: 7943 Comm: syz-executor695 Not tainted 5.1.0-rc5+ #78 [ 52.484847][ T7943] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 52.494893][ T7943] Call Trace: [ 52.498179][ T7943] dump_stack+0x172/0x1f0 [ 52.502604][ T7943] ? percpu_ref_kill_and_confirm+0x340/0x3b0 [ 52.508593][ T7943] panic+0x2cb/0x65c [ 52.512538][ T7943] ? __warn_printk+0xf3/0xf3 [ 52.517131][ T7943] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 52.523141][ T7943] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 52.529393][ T7943] ? __warn.cold+0x5/0x45 [ 52.533738][ T7943] ? __warn+0xe8/0x1d0 [ 52.537808][ T7943] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 52.543792][ T7943] __warn.cold+0x20/0x45 [ 52.548036][ T7943] ? vprintk_emit+0x1ce/0x6d0 [ 52.552715][ T7943] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 52.558851][ T7943] report_bug+0x263/0x2b0 [ 52.563193][ T7943] do_error_trap+0x11b/0x200 [ 52.567918][ T7943] do_invalid_op+0x37/0x50 [ 52.572343][ T7943] ? percpu_ref_kill_and_confirm+0x341/0x3b0 [ 52.578313][ T7943] invalid_op+0x14/0x20 [ 52.582461][ T7943] RIP: 0010:percpu_ref_kill_and_confirm+0x341/0x3b0 [ 52.589041][ T7943] 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 [ 52.608638][ T7943] RSP: 0018:ffff888093b0fcf0 EFLAGS: 00010082 [ 52.614701][ T7943] RAX: 0000000000000000 RBX: 0000607f5142fcdb RCX: 0000000000000000 [ 52.622709][ T7943] RDX: 0000000000000000 RSI: ffffffff815afcf6 RDI: ffffed1012761f90 [ 52.630706][ T7943] RBP: ffff888093b0fd20 R08: ffff88808fee8100 R09: fffffbfff1133639 [ 52.638675][ T7943] R10: fffffbfff1133638 R11: ffffffff8899b1c3 R12: ffff8880a559ac40 [ 52.646654][ T7943] R13: ffff8880a559ac48 R14: 0000000000000286 R15: 0000000000000000 [ 52.654647][ T7943] ? vprintk_func+0x86/0x189 [ 52.659239][ T7943] __io_uring_register+0xa7/0x1fe0 [ 52.664350][ T7943] ? __mutex_lock+0x3cd/0x1310 [ 52.669109][ T7943] ? __x64_sys_io_uring_register+0x182/0x1f0 [ 52.675089][ T7943] ? mutex_trylock+0x1e0/0x1e0 [ 52.679851][ T7943] ? io_sq_wq_submit_work+0x10f0/0x10f0 [ 52.685395][ T7943] ? kasan_check_write+0x14/0x20 [ 52.690331][ T7943] __x64_sys_io_uring_register+0x193/0x1f0 [ 52.696137][ T7943] do_syscall_64+0x103/0x610 [ 52.700729][ T7943] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 52.706619][ T7943] RIP: 0033:0x4467c9 [ 52.711929][ T7943] 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 [ 52.731526][ T7943] RSP: 002b:00007f8323ab8db8 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab [ 52.739955][ T7943] RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 00000000004467c9 [ 52.747927][ T7943] RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000003 [ 52.755909][ T7943] RBP: 00000000006dbc30 R08: 00007f8323ab9700 R09: 0000000000000000 [ 52.763903][ T7943] R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc3c [ 52.771870][ T7943] R13: 00007fff51d7e38f R14: 00007f8323ab99c0 R15: 20c49ba5e353f7cf [ 52.780747][ T7943] Kernel Offset: disabled [ 52.785154][ T7943] Rebooting in 86400 seconds..