[syzbot] [block?] BUG: unable to handle kernel paging request in __blk_mq_alloc_driver_tag

[syzbot] [block?] BUG: unable to handle kernel paging request in __blk_mq_alloc_driver_tag

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    f1b8fa82cab7 Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=10697d79580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d1128bc53f2ef7f3
dashboard link: https://syzkaller.appspot.com/bug?extid=b380cbb218c1ef0fe808
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/932d85a2bda2/disk-f1b8fa82.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5b6b8fb76e8d/vmlinux-f1b8fa82.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c246b61ee396/Image-f1b8fa82.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b380cbb218c1ef0fe808@syzkaller.appspotmail.com

nvme nvme0: Does your device have a faulty power saving mode enabled?
nvme nvme0: Try "nvme_core.default_ps_max_latency_us=0 pcie_aspm=off pcie_port_pm=off" and report a bug
Unable to handle kernel paging request at virtual address dfff800000000000
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
Mem abort info:
  ESR = 0x0000000096000005
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x05: level 1 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
  CM = 0, WnR = 0, TnD = 0, TagAccess = 0
  GCS = 0, Overlay = 0, DirtyBit = 0
[dfff800000000000] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1]  SMP
Modules linked in:
CPU: 0 UID: 0 PID: 4404 Comm: kworker/0:1H Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/07/2026
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : blk_mq_tag_is_reserved block/blk-mq.h:224 [inline]
pc : __blk_mq_alloc_driver_tag+0x118/0x554 block/blk-mq.c:1844
lr : blk_mq_tag_busy block/blk-mq.h:211 [inline]
lr : __blk_mq_alloc_driver_tag+0xbc/0x554 block/blk-mq.c:1842
sp : ffff800099507780
x26: 0000000000000000 x25: 1fffe000190d6c82 x24: dfff800000000000
x23: ffff0000c8044400 x22: 0000000000000004 x21: 00000000ffffffff
x20: ffff0000c86b6400 x19: ffff0000c86b6410 x18: 00000000ffffffff
x17: ffff80008a7d6000 x16: 0000000000000004 x15: ffff80008a35fda0
x14: ffff80008a5d5e28 x13: 0000000000000002 x12: 0000000000000000
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : ffff80008aa7bd88 x4 : 0000000000000000 x3 : ffff8000817944e8
x2 : 0000000000000000 x1 : ffff0000c81a3a80 x0 : 0000000000000000
Call trace:
 blk_mq_get_driver_tag block/blk-mq.h:374 [inline]
 blk_mq_prep_dispatch_rq block/blk-mq.c:2029 [inline]
 blk_mq_dispatch_rq_list+0x298/0x13a8 block/blk-mq.c:2108
 __blk_mq_sched_dispatch_requests+0x250/0x10e8 block/blk-mq-sched.c:299
 blk_mq_sched_dispatch_requests+0xa8/0x158 block/blk-mq-sched.c:329
 blk_mq_run_work_fn+0x214/0x2e4 block/blk-mq.c:2532
 worker_thread+0x798/0xbd0 kernel/workqueue.c:3486
 kthread+0x304/0x3d4 kernel/kthread.c:436
Code: 35001b08 910012d6 b94002b5 d343fec8 (38f86908) 
---[ end trace 0000000000000000 ]---
SMP: stopping secondary CPUs
Kernel Offset: disabled
CPU features: 0x14000000,003c0008,27020a02,a84ff6a7
Memory Limit: none
Rebooting in 86400 seconds..
----------------
Code disassembly (best guess):
   0:	35001b08 	cbnz	w8, 0x360
   4:	910012d6 	add	x22, x22, #0x4
   8:	b94002b5 	ldr	w21, [x21]
   c:	d343fec8 	lsr	x8, x22, #3
* 10:	38f86908 	ldrsb	w8, [x8, x24] <-- trapping instruction


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