linux-kernel - [syzbot] [arm?] WARNING in fpsimd_restore_current

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Message-ID: <690a8dc2.050a0220.3d0d33.0018.GAE@google.com>
Date: Tue, 04 Nov 2025 15:35:30 -0800
From: syzbot <syzbot+d4ab35af21e99d07ce67@...kaller.appspotmail.com>
To: catalin.marinas@....com, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com, 
	will@...nel.org
Subject: [syzbot] [arm?] WARNING in fpsimd_restore_current_state

Hello,

syzbot found the following issue on:

HEAD commit:    dcb6fa37fd7b Linux 6.18-rc3
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=11a79704580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b8b659f0cab27b22
dashboard link: https://syzkaller.appspot.com/bug?extid=d4ab35af21e99d07ce67
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=115fdf34580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1441d258580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ae6bec0d0398/disk-dcb6fa37.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dcc732da66c3/vmlinux-dcb6fa37.xz
kernel image: https://storage.googleapis.com/syzbot-assets/301d1bbdecc2/Image-dcb6fa37.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d4ab35af21e99d07ce67@...kaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 6720 at arch/arm64/kernel/fpsimd.c:370 task_fpsimd_load arch/arm64/kernel/fpsimd.c:370 [inline]
WARNING: CPU: 0 PID: 6720 at arch/arm64/kernel/fpsimd.c:370 fpsimd_restore_current_state+0x4cc/0x708 arch/arm64/kernel/fpsimd.c:1746
Modules linked in:
CPU: 0 UID: 0 PID: 6720 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : task_fpsimd_load arch/arm64/kernel/fpsimd.c:370 [inline]
pc : fpsimd_restore_current_state+0x4cc/0x708 arch/arm64/kernel/fpsimd.c:1746
lr : task_fpsimd_load arch/arm64/kernel/fpsimd.c:370 [inline]
lr : fpsimd_restore_current_state+0x4cc/0x708 arch/arm64/kernel/fpsimd.c:1746
sp : ffff8000a1047de0
x29: ffff8000a1047de0 x28: ffff0000dcfd9ec0 x27: 0000000000000000
x26: 0000000000000000 x25: 0000000000000008 x24: 0000000000000040
x23: 00000000000020ff x22: dfff800000000000 x21: 1fffe0001b9fb3d8
x20: 0000000000000000 x19: ffff0000dcfd9ec0 x18: 1fffe000337db690
x17: ffff80008ae011f8 x16: ffff80008052ae04 x15: 0000000000000001
x14: 1fffe0001b9fb3d8 x13: 0000000000000000 x12: 0000000000000000
x11: ffff60001b9fb3d9 x10: 0000000000ff0100 x9 : 0000000000000000
x8 : ffff0000dcfd9ec0 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000001 x4 : 0000000000000008 x3 : ffff8000801f8344
x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
 task_fpsimd_load arch/arm64/kernel/fpsimd.c:370 [inline] (P)
 fpsimd_restore_current_state+0x4cc/0x708 arch/arm64/kernel/fpsimd.c:1746 (P)
 arch_exit_to_user_mode_work arch/arm64/include/asm/entry-common.h:25 [inline]
 exit_to_user_mode_loop+0xe4/0x178 kernel/entry/common.c:46
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 arm64_exit_to_user_mode arch/arm64/kernel/entry-common.c:103 [inline]
 el0_svc+0x170/0x254 arch/arm64/kernel/entry-common.c:747
 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:765
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596
irq event stamp: 129
hardirqs last  enabled at (127): [<ffff80008ae151bc>] __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:159 [inline]
hardirqs last  enabled at (127): [<ffff80008ae151bc>] _raw_spin_unlock_irq+0x30/0x80 kernel/locking/spinlock.c:202
hardirqs last disabled at (129): [<ffff80008adecb80>] el1_brk64+0x20/0x54 arch/arm64/kernel/entry-common.c:434
softirqs last  enabled at (8): [<ffff8000801f95fc>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (128): [<ffff8000801f95c8>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
---[ end trace 0000000000000000 ]---


---
This report is generated by a bot. It may contain errors.
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