[syzbot] [usb?] BUG: sleeping function called from invalid context in dummy_dequeue

[syzbot <syzbot+8baacc4139f12fa77909@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    8d245acc1e88 Merge tag 'char-misc-6.17-rc3' of git://git.k..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11e42062580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=e1e1566c7726877e
dashboard link: https://syzkaller.appspot.com/bug?extid=8baacc4139f12fa77909
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13317062580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=14d5ea34580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/096739d8f0ec/disk-8d245acc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/83a21aa9b978/vmlinux-8d245acc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7e7f165a3b29/bzImage-8d245acc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8baacc4139f12fa77909@syzkaller.appspotmail.com

BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 6118, name: syz.0.17
preempt_count: 0, expected: 0
RCU nest depth: 0, expected: 0
1 lock held by syz.0.17/6118:
 #0: ffff888144724058 (&dum_hcd->dum->lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:44 [inline]
 #0: ffff888144724058 (&dum_hcd->dum->lock){+.+.}-{3:3}, at: dummy_dequeue+0x164/0x480 drivers/usb/gadget/udc/dummy_hcd.c:769
irq event stamp: 5054
hardirqs last  enabled at (5053): [<ffffffff8af9b343>] __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:159 [inline]
hardirqs last  enabled at (5053): [<ffffffff8af9b343>] _raw_spin_unlock_irq+0x23/0x50 kernel/locking/spinlock.c:202
hardirqs last disabled at (5054): [<ffffffff86fc2471>] dummy_dequeue+0x151/0x480 drivers/usb/gadget/udc/dummy_hcd.c:768
softirqs last  enabled at (0): [<ffffffff81828ba9>] rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
softirqs last  enabled at (0): [<ffffffff81828ba9>] rcu_read_lock include/linux/rcupdate.h:841 [inline]
softirqs last  enabled at (0): [<ffffffff81828ba9>] copy_process+0x979/0x3ae0 kernel/fork.c:2043
softirqs last disabled at (0): [<0000000000000000>] 0x0
CPU: 0 UID: 0 PID: 6118 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 __might_resched+0x44b/0x5d0 kernel/sched/core.c:8957
 __rt_spin_lock kernel/locking/spinlock_rt.c:48 [inline]
 rt_spin_lock+0xc7/0x2c0 kernel/locking/spinlock_rt.c:57
 spin_lock include/linux/spinlock_rt.h:44 [inline]
 dummy_dequeue+0x164/0x480 drivers/usb/gadget/udc/dummy_hcd.c:769
 usb_ep_dequeue+0x66/0x250 drivers/usb/gadget/udc/core.c:330
 raw_process_ep_io+0x5a3/0xaf0 drivers/usb/gadget/legacy/raw_gadget.c:1124
 raw_ioctl_ep_write drivers/usb/gadget/legacy/raw_gadget.c:1152 [inline]
 raw_ioctl+0x22dc/0x3ba0 drivers/usb/gadget/legacy/raw_gadget.c:1324
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1608d4e7eb
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
RSP: 002b:00007ffdcd9fcf80 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000044 RCX: 00007f1608d4e7eb
RDX: 00007ffdcd9fd000 RSI: 0000000040085507 RDI: 0000000000000003
RBP: 0000000000000003 R08: 00007f16090a0320 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 0000200000000080
R13: 000000000000000a R14: 00007f1608f75fa0 R15: 0000000000000004
 </TASK>


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