------------[ cut here ]------------
percpu_ref_kill_and_confirm called more than once on io_ring_ctx_ref_free!
WARNING: CPU: 1 PID: 8929 at lib/percpu-refcount.c:335 percpu_ref_kill_and_confirm+0x341/0x3b0 lib/percpu-refcount.c:335
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 8929 Comm: syz-executor.3 Not tainted 5.1.0-rc6-next-20190426 #31
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 panic+0x2cb/0x75a kernel/panic.c:218
 __warn.cold+0x20/0x47 kernel/panic.c:580
 report_bug+0x263/0x2b0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:179 [inline]
 fixup_bug arch/x86/kernel/traps.c:174 [inline]
 do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:272
 do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:291
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:972
RIP: 0010:percpu_ref_kill_and_confirm+0x341/0x3b0 lib/percpu-refcount.c:335
Code: 47 2c 28 06 01 48 89 fa 48 c1 ea 03 80 3c 02 00 75 76 49 8b 54 24 10 48 c7 c6 60 22 a2 87 48 c7 c7 00 22 a2 87 e8 8d 37 0f fe <0f> 0b 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 80 3c 02
RSP: 0018:ffff888087d77cf0 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000607f51490003 RCX: 0000000000000000
RDX: 0000000000009cff RSI: ffffffff815b4656 RDI: ffffed1010faef90
RBP: ffff888087d77d20 R08: ffff888093dba180 R09: fffffbfff1133011
R10: fffffbfff1133010 R11: ffffffff88998083 R12: ffff88809ac62300
R13: ffff88809ac62308 R14: 0000000000000286 R15: 0000000000000000
 percpu_ref_kill include/linux/percpu-refcount.h:128 [inline]
 __io_uring_register+0xa7/0x1fe0 fs/io_uring.c:2938
 __do_sys_io_uring_register fs/io_uring.c:2999 [inline]
 __se_sys_io_uring_register fs/io_uring.c:2981 [inline]
 __x64_sys_io_uring_register+0x193/0x1f0 fs/io_uring.c:2981
 do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x458da9
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f9d59fd5c78 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000458da9
RDX: 00000000200001c0 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 00007f9d59fd66d4
R13: 00000000004cb820 R14: 00000000004d22b8 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..