[v6.1] WARNING: locking bug in gfs2_quotad

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cd9b81672742 Linux 6.1.161
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13c91bfa580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b1adc0bfde2d8a4a
dashboard link: https://syzkaller.appspot.com/bug?extid=2f84a38870fecbe1ad2c
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d21df4411014/disk-cd9b8167.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/246aed0358fb/vmlinux-cd9b8167.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a6f546504ec2/Image-cd9b8167.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2f84a3...@syzkaller.appspotmail.com

------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(1)
WARNING: CPU: 0 PID: 5133 at kernel/locking/lockdep.c:232 hlock_class kernel/locking/lockdep.c:-1 [inline]
WARNING: CPU: 0 PID: 5133 at kernel/locking/lockdep.c:232 check_wait_context kernel/locking/lockdep.c:4723 [inline]
WARNING: CPU: 0 PID: 5133 at kernel/locking/lockdep.c:232 __lock_acquire+0x6fc/0x6800 kernel/locking/lockdep.c:4999
Modules linked in:
CPU: 0 PID: 5133 Comm: gfs2_quotad Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
pstate: 624000c5 (nZCv daIF +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : hlock_class kernel/locking/lockdep.c:-1 [inline]
pc : check_wait_context kernel/locking/lockdep.c:4723 [inline]
pc : __lock_acquire+0x6fc/0x6800 kernel/locking/lockdep.c:4999
lr : hlock_class kernel/locking/lockdep.c:232 [inline]
lr : check_wait_context kernel/locking/lockdep.c:4723 [inline]
lr : __lock_acquire+0x6f4/0x6800 kernel/locking/lockdep.c:4999
sp : ffff800023077940
x29: ffff800023077b50 x28: dfff800000000000 x27: 0000000000000001
x26: ffff0000cadd41f8 x25: ffff0000cadd41f0 x24: dfff800000000000
x23: dfff800000000000 x22: 0000000000000000 x21: 00000000000014c6
x20: ffff8000180f8bd8 x19: ffff0000cadd421c x18: ffff800011b7bf60
x17: 0000000000000000 x16: ffff8000082ef028 x15: 0000000000000000
x14: 0000000000000001 x13: 1fffe00033eaaba3 x12: 0000000000ff0100
x11: ff00800008194238 x10: ffff0000cadd4218 x9 : cf71346b8c729700
x8 : 0000000000000000 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff8000230773d8 x4 : ffff8000152e4cc0 x3 : ffff800008538160
x2 : 0000000000000001 x1 : 0000000100000001 x0 : 0000000000000000
Call trace:
hlock_class kernel/locking/lockdep.c:-1 [inline]
check_wait_context kernel/locking/lockdep.c:4723 [inline]
__lock_acquire+0x6fc/0x6800 kernel/locking/lockdep.c:4999
lock_acquire+0x20c/0x63c kernel/locking/lockdep.c:5662
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x6c/0xb0 kernel/locking/spinlock.c:162
finish_wait+0xc8/0x1ac kernel/sched/wait.c:410
gfs2_quotad+0x390/0x500 fs/gfs2/quota.c:1579
kthread+0x250/0x2d8 kernel/kthread.c:376
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850
irq event stamp: 1330
hardirqs last enabled at (1329): [<ffff80000a8dbafc>] __free_object+0x1e0/0x894 lib/debugobjects.c:355
hardirqs last disabled at (1330): [<ffff800011b070f0>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline]
hardirqs last disabled at (1330): [<ffff800011b070f0>] _raw_spin_lock_irqsave+0xa4/0xb0 kernel/locking/spinlock.c:162
softirqs last enabled at (1284): [<ffff8000081ac37c>] softirq_handle_end kernel/softirq.c:439 [inline]
softirqs last enabled at (1284): [<ffff8000081ac37c>] handle_softirqs+0xaec/0xc60 kernel/softirq.c:624
softirqs last disabled at (1163): [<ffff800008020164>] __do_softirq+0x14/0x20 kernel/softirq.c:630
---[ end trace 0000000000000000 ]---
Unable to handle kernel paging request at virtual address dfff800000000017
KASAN: null-ptr-deref in range [0x00000000000000b8-0x00000000000000bf]
Mem abort info:
ESR = 0x0000000096000006
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x06: level 2 translation fault
Data abort info:
ISV = 0, ISS = 0x00000006
CM = 0, WnR = 0
[dfff800000000017] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 5133 Comm: gfs2_quotad Tainted: G W syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
pstate: 624000c5 (nZCv daIF +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : check_wait_context kernel/locking/lockdep.c:4723 [inline]
pc : __lock_acquire+0x4c8/0x6800 kernel/locking/lockdep.c:4999
lr : hlock_class kernel/locking/lockdep.c:232 [inline]
lr : check_wait_context kernel/locking/lockdep.c:4723 [inline]
lr : __lock_acquire+0x6f4/0x6800 kernel/locking/lockdep.c:4999
sp : ffff800023077940
x29: ffff800023077b50 x28: dfff800000000000 x27: 0000000000000001
x26: ffff0000cadd41f8 x25: ffff0000cadd41f0 x24: dfff800000000000
x23: dfff800000000000 x22: 0000000000000000 x21: 00000000000014c6
x20: ffff8000180f8bd8 x19: 00000000000000b8 x18: ffff800011b7bf60
x17: 0000000000000000 x16: ffff8000082ef028 x15: 0000000000000000
x14: 0000000000000001 x13: 1fffe00033eaaba3 x12: 0000000000ff0100
x11: ff00800008194238 x10: ffff0000cadd4218 x9 : cf71346b8c729700
x8 : 0000000000000017 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff8000230773d8 x4 : ffff8000152e4cc0 x3 : ffff800008538160
x2 : 0000000000000001 x1 : 0000000100000001 x0 : 0000000000000000
Call trace:
check_wait_context kernel/locking/lockdep.c:4723 [inline]
__lock_acquire+0x4c8/0x6800 kernel/locking/lockdep.c:4999
lock_acquire+0x20c/0x63c kernel/locking/lockdep.c:5662
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x6c/0xb0 kernel/locking/spinlock.c:162
finish_wait+0xc8/0x1ac kernel/sched/wait.c:410
gfs2_quotad+0x390/0x500 fs/gfs2/quota.c:1579
kthread+0x250/0x2d8 kernel/kthread.c:376
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850
Code: 34000fe8 aa1f03e8 9102e113 d343fe68 (38fc6908)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 34000fe8 cbz w8, 0x1fc
4: aa1f03e8 mov x8, xzr
8: 9102e113 add x19, x8, #0xb8
c: d343fe68 lsr x8, x19, #3
* 10: 38fc6908 ldrsb w8, [x8, x28] <-- trapping instruction


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