------------[ cut here ]------------
WARNING: CPU: 0 PID: 9630 at lib/percpu-refcount.c:111 percpu_ref_exit+0xa3/0xd0 lib/percpu-refcount.c:111
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 9630 Comm: syz-executor.4 Not tainted 5.6.0-rc3-next-20200228-syzkaller #0
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+0x188/0x20d lib/dump_stack.c:118
 panic+0x2e3/0x75c kernel/panic.c:221
 __warn.cold+0x2f/0x35 kernel/panic.c:582
 report_bug+0x27b/0x2f0 lib/bug.c:195
 fixup_bug arch/x86/kernel/traps.c:175 [inline]
 fixup_bug arch/x86/kernel/traps.c:170 [inline]
 do_error_trap+0x12b/0x220 arch/x86/kernel/traps.c:267
 do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
 invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:percpu_ref_exit+0xa3/0xd0 lib/percpu-refcount.c:111
Code: 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 75 1a 48 c7 43 08 03 00 00 00 5b 5d 41 5c e9 f2 6e e3 fd e8 ed 6e e3 fd <0f> 0b eb c2 4c 89 e7 e8 01 90 20 fe eb dc e8 7a 8f 20 fe eb aa 4c
RSP: 0018:ffffc90002fa7cb8 EFLAGS: 00010216
RAX: 0000000000040000 RBX: ffff888093f9ea10 RCX: ffffc90012362000
RDX: 00000000000016b8 RSI: ffffffff838f2693 RDI: ffff888093f9ea28
RBP: 0000607f51403280 R08: ffff888096666040 R09: ffffed10127f3d4a
R10: ffffed10127f3d49 R11: ffff888093f9ea4f R12: ffff888093f9ea18
R13: 0000000000000003 R14: ffff8880926b1000 R15: 0000000000000000
 io_sqe_files_unregister+0x8a/0x2f0 fs/io_uring.c:5412
 __io_uring_register+0xfea/0x2b40 fs/io_uring.c:7175
 __do_sys_io_uring_register fs/io_uring.c:7249 [inline]
 __se_sys_io_uring_register fs/io_uring.c:7231 [inline]
 __x64_sys_io_uring_register+0x192/0x560 fs/io_uring.c:7231
 do_syscall_64+0xf6/0x790 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c4a9
Code: ad b6 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 b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f9b345dbc78 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab
RAX: ffffffffffffffda RBX: 00007f9b345dc6d4 RCX: 000000000045c4a9
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000003
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000201 R14: 00000000004d2a00 R15: 000000000076bf2c
Kernel Offset: disabled
Rebooting in 86400 seconds..