------------[ cut here ]------------
WARNING: CPU: 1 PID: 7 at lib/percpu-refcount.c:112 percpu_ref_exit+0xa3/0xd0 lib/percpu-refcount.c:112
Modules linked in:
CPU: 1 PID: 7 Comm: kworker/u4:0 Not tainted 5.9.0-rc2-next-20200828-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound io_ring_exit_work
RIP: 0010:percpu_ref_exit+0xa3/0xd0 lib/percpu-refcount.c:112
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 d2 ea d7 fd e8 cd ea d7 fd <0f> 0b eb c2 4c 89 e7 e8 a1 66 18 fe eb dc e8 1a 66 18 fe eb aa 4c
RSP: 0018:ffffc90000cdfca8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff8880a6d3a000 RCX: ffffffff839c915d
RDX: ffff8880a95e01c0 RSI: ffffffff839c91c3 RDI: ffff8880a6d3a018
RBP: 0000607f5167c5b0 R08: 0000000000000001 R09: ffffffff8c6a5abf
R10: 0000000000000000 R11: 0000000000000160 R12: ffff8880a6d3a008
R13: 0000000000000000 R14: ffff8880a6d3a101 R15: 0000000000000005
FS:  0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000052c538 CR3: 0000000095d78000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 io_ring_ctx_free fs/io_uring.c:7874 [inline]
 io_ring_exit_work+0x466/0x6d0 fs/io_uring.c:7936
 process_one_work+0x94c/0x1670 kernel/workqueue.c:2269
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
 kthread+0x3b5/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294