[syzbot] [kernel?] WARNING in kthread_affine_node

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 365f9c7a6b81 Merge branches 'for-next/core' and 'for-next/..
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=145238c6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=72c97575381cec47
dashboard link: https://syzkaller.appspot.com/bug?extid=37ca7ae3e98cb65c3209
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1170a49e580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16b7ffde580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/eafe0adb7386/disk-365f9c7a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/29422d607579/vmlinux-365f9c7a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/98ca955a8b54/Image-365f9c7a.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+37ca7a...@syzkaller.appspotmail.com

alloc_cpumask_var_node+0xfc/0x138 lib/cpumask.c:35
alloc_cpumask_var include/linux/cpumask.h:1054 [inline]
zalloc_cpumask_var include/linux/cpumask.h:1060 [inline]
kthread_affine_node+0x148/0x2e8 kernel/kthread.c:358
kthread+0x29c/0x3d4 kernel/kthread.c:430
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:842
------------[ cut here ]------------
WARNING: kernel/kthread.c:359 at kthread_affine_node+0x200/0x2e8 kernel/kthread.c:359, CPU#0: napi/wg2-0/5207
Modules linked in:
CPU: 0 UID: 0 PID: 5207 Comm: napi/wg2-0 Not tainted syzkaller #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : kthread_affine_node+0x200/0x2e8 kernel/kthread.c:359
lr : kthread_affine_node+0x200/0x2e8 kernel/kthread.c:359
sp : ffff800095fe7d80
x29: ffff800095fe7df0 x28: 1fffe000198cf3ad x27: 1fffe000198cf483
x26: ffff0000cc67a418 x25: 1fffe000198cf3ad x24: dfff800000000000
x23: ffff700012bfcfb0 x22: ffff800095fe7d80 x21: 0000000000000000
x20: ffff0000f1573400 x19: ffff0000cc679d40 x18: 1fffe00035bc5428
x17: 70202c31206c6176 x16: 0000000000000001 x15: 0000000000000000
x14: 0000000000000000 x13: 0000000000000001 x12: 0000000000000004
x11: ffff800080156ee8 x10: 0000000000000003 x9 : 0000000000000000
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000001 x4 : 0000000000000008 x3 : ffff800080131d60
x2 : 0000000000000080 x1 : ffff0000cc679d40 x0 : 0000000000000000
Call trace:
kthread_affine_node+0x200/0x2e8 kernel/kthread.c:359 (P)
kthread+0x29c/0x3d4 kernel/kthread.c:430
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:842
irq event stamp: 20
hardirqs last enabled at (19): [<ffff800080131d48>] dump_stack_lvl+0xe8/0x12c lib/dump_stack.c:123
hardirqs last disabled at (20): [<ffff8000868dfe78>] el1_brk64+0x20/0x54 arch/arm64/kernel/entry-common.c:425
softirqs last enabled at (0): [<ffff8000802edeb0>] copy_process+0x13a4/0x32e8 kernel/fork.c:2238
softirqs last disabled at (0): [<0000000000000000>] 0x0
---[ end trace 0000000000000000 ]---


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