[syzbot] [block?] WARNING in blk_mq_free_tag_set

[syzbot <syzbot+02b37e31e64ea5cb6d29@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    6b8c8af514d7 Add linux-next specific files for 20260807
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=11d2bfb9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6d343b54cc50df0f
dashboard link: https://syzkaller.appspot.com/bug?extid=02b37e31e64ea5cb6d29
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=10f56132580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/71ff4edcb608/disk-6b8c8af5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1f5fa331d8f2/vmlinux-6b8c8af5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f993558ec63b/bzImage-6b8c8af5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+02b37e31e64ea5cb6d29@syzkaller.appspotmail.com

------------[ cut here ]------------
timer_delete_sync(&sdp->delay_work)
WARNING: kernel/rcu/srcutree.c:706 at cleanup_srcu_struct+0x3aa/0x890 kernel/rcu/srcutree.c:706, CPU#1: kworker/u8:11/3800
Modules linked in:
CPU: 1 UID: 0 PID: 3800 Comm: kworker/u8:11 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: nbd-del nbd_dev_remove_work
RIP: 0010:cleanup_srcu_struct+0x3aa/0x890 kernel/rcu/srcutree.c:706
Code: b9 8a 00 48 83 7d 00 00 4c 8b 74 24 10 0f 85 dd 03 00 00 41 ff c5 41 83 e5 0f 41 83 fd 07 0f 86 0e ff ff ff e9 ab 00 00 00 90 <0f> 0b 90 4c 8d b5 00 02 00 00 4c 89 f3 48 c1 eb 03 48 b8 00 00 00
RSP: 0018:ffffc9000e69f9d0 EFLAGS: 00010202
RAX: 0000000000000001 RBX: 0000607edad2e8c0 RCX: 0000000000000000
RDX: 0000000000000006 RSI: ffffffff8e253559 RDI: 00000000ffffffff
RBP: ffffe8ffffc3a8c0 R08: ffffffff9058fb7f R09: 1ffffffff20b1f6f
R10: dffffc0000000000 R11: fffffbfff20b1f70 R12: ffff88802b760000
R13: 0000000000000000 R14: ffffffff8e5237d0 R15: 1ffffffff1ca47de
FS:  0000000000000000(0000) GS:ffff88812500c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbb3d026e9c CR3: 000000000e948000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 blk_mq_free_tag_set+0x617/0x780 block/blk-mq.c:4976
 nbd_dev_remove drivers/block/nbd.c:269 [inline]
 nbd_dev_remove_work+0x4f/0xe0 drivers/block/nbd.c:284
 process_one_work kernel/workqueue.c:3375 [inline]
 process_scheduled_works+0xc4e/0x1630 kernel/workqueue.c:3458
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3539
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


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