!list_empty(&req->queue)
WARNING: drivers/usb/gadget/udc/dummy_hcd.c:710 at dummy_free_request+0x7d/0x90 drivers/usb/gadget/udc/dummy_hcd.c:710, CPU#2: syz.2.831/8225
Modules linked in:

CPU: 2 UID: 0 PID: 8225 Comm: syz.2.831 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:dummy_free_request+0x7d/0x90 drivers/usb/gadget/udc/dummy_hcd.c:710
Code: 5b 9e fa e8 55 ed 39 fa 5b 5d e9 4e fb ed 03 e8 49 ed 39 fa 90 0f 0b 90 e8 40 ed 39 fa 5b 5d c3 cc cc cc cc e8 34 ed 39 fa 90 <0f> 0b 90 eb c7 48 89 ef e8 46 77 aa fa eb b4 0f 1f 40 00 90 90 90
RSP: 0018:ffffc90006eafbe0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88805a61e410 RCX: ffffffff87cfb441
RDX: ffff88805abb0000 RSI: ffffffff87d077ac RDI: ffff888025c5c068
RBP: ffff88805a61e400 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff90256740
R13: ffff888025c5cc00 R14: ffff88805948d044 R15: ffff888025c5cc00
FS:  000055558088b500(0000) GS:ffff8880d5fd8000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f61759beff8 CR3: 00000000324fd000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 gadgetfs_unbind+0x1e1/0x260 drivers/usb/gadget/legacy/inode.c:1661
 gadget_unbind_driver+0x20c/0x4f0 drivers/usb/gadget/udc/core.c:1724
 device_remove+0xcb/0x180 drivers/base/dd.c:616
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
 driver_detach+0xd8/0x1b0 drivers/base/dd.c:1435
 bus_remove_driver+0x13b/0x2e0 drivers/base/bus.c:832
 driver_unregister+0x76/0xb0 drivers/base/driver.c:202
 usb_gadget_unregister_driver+0x49/0x70 drivers/usb/gadget/udc/core.c:1784
 dev_release+0x132/0x1b0 drivers/usb/gadget/legacy/inode.c:1198
 __fput+0x3ff/0xb50 fs/file_table.c:512
 task_work_run+0x150/0x240 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:70 [inline]
 exit_to_user_mode_loop+0x1d8/0x6f0 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x666/0x870 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6174b9e019
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffeb21009b8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f6174e27da0 RCX: 00007f6174b9e019
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f6174e27da0 R08: 00007f6174e26308 R09: 0000000000000000
R10: 00000000003ff788 R11: 0000000000000246 R12: 0000000000020c9d
R13: 00007f6174e2636c R14: 0000000000020a73 R15: 00007f6174e26360
 </TASK>