[v6.1] kernel BUG in raid5_run

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fb28aa725e05 Linux 6.1.180
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16f093b9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=872c04466179833f
dashboard link: https://syzkaller.appspot.com/bug?extid=a8dc03ba661ea0326b0c
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/d420eb944682/disk-fb28aa72.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/affae450ab23/vmlinux-fb28aa72.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b9e6919ed519/Image-fb28aa72.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a8dc03...@syzkaller.appspotmail.com

md/raid:md0: not clean -- starting background reconstruction
------------[ cut here ]------------
kernel BUG at drivers/md/raid5.c:7902!
Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4779 Comm: syz.0.105 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : raid5_run+0x23dc/0x24c4 drivers/md/raid5.c:7902
lr : raid5_run+0x23dc/0x24c4 drivers/md/raid5.c:7902
sp : ffff8000249c7770
x29: ffff8000249c7840 x28: ffff0000ce0e0000 x27: dfff800000000000
x26: ffff0000ce0e0028 x25: ffff0000ce0e0018 x24: 0000000000000000
x23: 0000000000000000 x22: 0000000000000000 x21: 00000000ffffffff
x20: 1fffe00019c1c005 x19: ffff0000ce0e0148 x18: 1fffe00033e7277e
x17: ffff80001537d000 x16: ffff800011b90080 x15: ffff00019f393bfc
x14: 0000000000000001 x13: 1ffff00004938e54 x12: 0000000000080000
x11: 000000000000a262 x10: ffff800021f49000 x9 : ffff80000ea6cadc
x8 : 000000000000a263 x7 : ffff80000825ab50 x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : ffff80000a927f5c
x2 : ffff00019f393d10 x1 : 0000000000000000 x0 : 00000000ffffffff
Call trace:
raid5_run+0x23dc/0x24c4 drivers/md/raid5.c:7902
md_run+0xe14/0x1de0 drivers/md/md.c:6020
do_md_run+0x4c/0x4a4 drivers/md/md.c:6152
array_state_store+0x5e8/0x944 drivers/md/md.c:-1
md_attr_store+0x168/0x234 drivers/md/md.c:5626
sysfs_kf_write+0x1f8/0x274 fs/sysfs/file.c:140
kernfs_fop_write_iter+0x390/0x4b4 fs/kernfs/file.c:352
call_write_iter include/linux/fs.h:2265 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x3c8/0x7c8 fs/read_write.c:584
ksys_write+0x12c/0x228 fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__arm64_sys_write+0x7c/0x90 fs/read_write.c:646
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: 17fff894 9669183d d4210000 9669183b (d4210000)
---[ end trace 0000000000000000 ]---


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