[moderation] [rcu?] BUG: unable to handle kernel paging request in rcu_cblist_dequeue

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a82e92598ab1 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=176622d4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2727a5e5fea443ee
dashboard link: https://syzkaller.appspot.com/bug?extid=3fed4ee555d69bb415a9
compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
userspace arch: arm64
CC: [boqun...@gmail.com fred...@kernel.org jiangs...@gmail.com jo...@joelfernandes.org jo...@joshtriplett.org linux-...@vger.kernel.org mathieu....@efficios.com neeraj....@kernel.org pau...@kernel.org qiang.z...@gmail.com r...@vger.kernel.org ros...@goodmis.org ure...@gmail.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a55403ab11f8/disk-a82e9259.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/437d0df42202/vmlinux-a82e9259.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ad05ab5fed96/Image-a82e9259.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3fed4e...@syzkaller.appspotmail.com

Unable to handle kernel paging request at virtual address ffef801407ee7000
KASAN: maybe wild-memory-access in range [0xff8000a03f738000-0xff8000a03f738007]
Mem abort info:
ESR = 0x0000000096000004
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x04: level 0 translation fault
Data abort info:
ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
CM = 0, WnR = 0, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[ffef801407ee7000] address between user and kernel address ranges
Internal error: Oops: 0000000096000004 [#1] SMP
Modules linked in:
CPU: 0 UID: 0 PID: 11 Comm: kworker/0:1 Not tainted 6.15.0-rc6-syzkaller-ga82e92598ab1 #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: rcu_gp srcu_invoke_callbacks
pstate: 00400005 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : rcu_cblist_dequeue+0x68/0xc8 kernel/rcu/rcu_segcblist.c:75
lr : srcu_invoke_callbacks+0x198/0x394 kernel/rcu/srcutree.c:1800
sp : ffff800097647960
x29: ffff800097647960 x28: ffff8000976479c0 x27: dfff800000000000
x26: 0000000000000000 x25: ffff0000c1a1a918 x24: fffffdffbf6ee5c0
x23: 1ffff00012ec8f3c x22: dfff800000000000 x21: ffff8000976479f0
x20: ff8000a03f738000 x19: ffff8000976479e0 x18: 1fffe0003386aa76
x17: ffff80008f31e000 x16: ffff80008051c2cc x15: 0000000000000001
x14: 1fffffbff7eddcb8 x13: 0000000000000000 x12: 0000000000000000
x11: ffff800092d35c40 x10: 0000000000000001 x9 : 1ff0001407ee7000
x8 : 0000000000000000 x7 : ffff8000805a49dc x6 : 0000000000000000
x5 : 0000000000000001 x4 : 0000000000000001 x3 : 0000000000000010
x2 : 0000000000000006 x1 : ffff80008e9036c1 x0 : ffff8000976479e0
Call trace:
rcu_cblist_dequeue+0x68/0xc8 kernel/rcu/rcu_segcblist.c:74 (P)
srcu_invoke_callbacks+0x198/0x394 kernel/rcu/srcutree.c:1800
process_one_work+0x7e8/0x156c kernel/workqueue.c:3238
process_scheduled_works kernel/workqueue.c:3319 [inline]
worker_thread+0x958/0xed8 kernel/workqueue.c:3400
kthread+0x5fc/0x75c kernel/kthread.c:464
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:847
Code: f94002a8 d343fe89 d1000508 f90002a8 (38766928)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: f94002a8 ldr x8, [x21]
4: d343fe89 lsr x9, x20, #3
8: d1000508 sub x8, x8, #0x1
c: f90002a8 str x8, [x21]
* 10: 38766928 ldrb w8, [x9, x22] <-- trapping instruction


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