[syzbot] [block?] WARNING in blk_mq_alloc_tag_set

[syzbot <syzbot+18431bc7dccedc61778f@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    d326f83e819c Merge tag 'net-7.2-rc5' of git://git.kernel.o..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=129f3bde580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5c4196ba0e33631d
dashboard link: https://syzkaller.appspot.com/bug?extid=18431bc7dccedc61778f
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9359ac22935d/disk-d326f83e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c8a632e638dc/vmlinux-d326f83e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/db78e854ce3e/bzImage-d326f83e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+18431bc7dccedc61778f@syzkaller.appspotmail.com

blk-mq: failed to allocate request map
------------[ cut here ]------------
rcu_segcblist_n_cbs(&sdp->srcu_cblist)
WARNING: kernel/rcu/srcutree.c:730 at cleanup_srcu_struct+0x369/0x470 kernel/rcu/srcutree.c:730, CPU#1: iou-wrk-11407/11411
Modules linked in:
CPU: 1 UID: 0 PID: 11411 Comm: iou-wrk-11407 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/10/2026
RIP: 0010:cleanup_srcu_struct+0x369/0x470 kernel/rcu/srcutree.c:730
Code: 7c 35 00 00 74 08 4c 89 ff e8 b3 44 89 00 49 c7 07 00 00 00 00 48 83 c4 28 5b 41 5c 41 5d 41 5e 41 5f 5d e9 34 80 65 ff cc 90 <0f> 0b 90 eb e6 90 0f 0b 90 eb e0 90 0f 0b 90 eb da 90 0f 0b 90 eb
RSP: 0018:ffffc9001e1f7740 EFLAGS: 00010202
RAX: 1ffffd1ffff92d11 RBX: 1ffffffff1c9f5de RCX: b62894e921e22600
RDX: 0000000000000001 RSI: ffffffff8e4b12ee RDI: ffff888034b93e00
RBP: ffffe8ffffc96888 R08: ffffe8ffffc96927 R09: 1ffffd1ffff92d24
R10: dffffc0000000000 R11: fffff91ffff92d25 R12: ffff8880330a4160
R13: 0000000000000000 R14: dffffc0000000000 R15: 0000607edad447c0
FS:  00007f420a7846c0(0000) GS:ffff888125052000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000029000 CR3: 000000007d20d000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 blk_mq_alloc_tag_set+0xc77/0x1000 block/blk-mq.c:4928
 ublk_ctrl_add_dev+0x903/0xbc0 drivers/block/ublk_drv.c:4797
 ublk_ctrl_uring_cmd+0x696/0x7e0 drivers/block/ublk_drv.c:5783
 io_uring_cmd+0x2e6/0x8b0 io_uring/uring_cmd.c:271
 __io_issue_sqe+0x188/0x4d0 io_uring/io_uring.c:1395
 io_issue_sqe+0x16d/0x1020 io_uring/io_uring.c:1418
 io_wq_submit_work+0x7ab/0xc90 io_uring/io_uring.c:1534
 io_worker_handle_work+0x72e/0x10d0 io_uring/io-wq.c:652
 io_wq_worker+0x452/0xf10 io_uring/io-wq.c:706
 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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