------------[ cut here ]------------ percpu_ref_kill_and_confirm called more than once on io_ring_ctx_ref_free! WARNING: CPU: 0 PID: 28678 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: 0 PID: 28678 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:ffff888060aa7cf0 EFLAGS: 00010082 RAX: 0000000000000000 RBX: 0000607f514aa313 RCX: 0000000000000000 RDX: 0000000000009970 RSI: ffffffff815b4656 RDI: ffffed100c154f90 RBP: ffff888060aa7d20 R08: ffff8880a7b92600 R09: fffffbfff1133011 R10: fffffbfff1133010 R11: ffffffff88998083 R12: ffff888095d7aa80 R13: ffff888095d7aa88 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:00007f6620c86c78 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000000458da9 RDX: 0000000020000440 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000004 R11: 0000000000000246 R12: 00007f6620c876d4 R13: 00000000004cb820 R14: 00000000004d22b8 R15: 00000000ffffffff Kernel Offset: disabled Rebooting in 86400 seconds..