[syzbot] [block?] WARNING: lock held when returning to user space in blk_throtl_init

[syzbot <syzbot+1eb53c83ab8b0a0302a6@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    becb95e45ef0 Add linux-next specific files for 20261009
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=119ea68e580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7400eab0484d1dc
dashboard link: https://syzkaller.appspot.com/bug?extid=1eb53c83ab8b0a0302a6
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=100e8999580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=159ea68e580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b16b9c03e69c/disk-becb95e4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/78483614b526/vmlinux-becb95e4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e333f1b9fe69/bzImage-becb95e4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1eb53c83ab8b0a0302a6@syzkaller.appspotmail.com

null_blk: disk nullb1 created
================================================
WARNING: lock held when returning to user space!
syzkaller #0 Not tainted
------------------------------------------------
syz.0.452/6787 is leaving the kernel with locks still held!
locks held by syz.0.452/6787: 2, last CPU#0:
 #0: ffff88803652c190 (&q->q_usage_counter(io)#105){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:956 [inline]
 #0: ffff88803652c190 (&q->q_usage_counter(io)#105){++++}-{0:0}, at: blk_throtl_init+0x27b/0x420 block/blk-throttle.c:1332
 #1: ffff88803652c1c8 (&q->q_usage_counter(queue)#88){+.+.}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:956 [inline]
 #1: ffff88803652c1c8 (&q->q_usage_counter(queue)#88){+.+.}-{0:0}, at: blk_throtl_init+0x27b/0x420 block/blk-throttle.c:1332


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