[moderation] [mm?] BUG: spinlock bad magic in __percpu_counter_sum

Hello,

syzbot found the following issue on:

HEAD commit: 5723cc3450bc Merge tag 'dmaengine-fix-6.15' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=152adf68580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ea35e429f965296e
dashboard link: https://syzkaller.appspot.com/bug?extid=8438d5251c5448479dad
compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
CC: [[email protected] [email protected] [email protected] [email protected] [email protected]]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5b398dca63b1/disk-5723cc34.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/88d33dc7d7cc/vmlinux-5723cc34.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ce17ee3aa45c/bzImage-5723cc34.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]

overlayfs: missing 'lowerdir'
BUG: spinlock bad magic on CPU#0, syz.5.1359/10894
lock: 0xffff8880328ac808, .magic: ffff8880, .owner: <none>/-1, .owner_cpu: -1
CPU: 0 UID: 0 PID: 10894 Comm: syz.5.1359 Not tainted 6.15.0-rc6-syzkaller-00346-g5723cc3450bc #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
spin_bug kernel/locking/spinlock_debug.c:78 [inline]
debug_spin_lock_before kernel/locking/spinlock_debug.c:86 [inline]
do_raw_spin_lock+0x1ca/0x290 kernel/locking/spinlock_debug.c:115
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
_raw_spin_lock_irqsave+0xb3/0xf0 kernel/locking/spinlock.c:162
__percpu_counter_sum+0x2c/0x1e0 lib/percpu_counter.c:177
percpu_counter_sum include/linux/percpu_counter.h:105 [inline]
shmem_statfs+0x13d/0x2b0 mm/shmem.c:3815
statfs_by_dentry fs/statfs.c:66 [inline]
vfs_statfs+0x147/0x2d0 fs/statfs.c:90
ovl_check_namelen fs/overlayfs/super.c:388 [inline]
ovl_get_upper fs/overlayfs/super.c:506 [inline]
ovl_fill_super+0x788/0x35d0 fs/overlayfs/super.c:1392
vfs_get_super fs/super.c:1280 [inline]
get_tree_nodev+0xbb/0x150 fs/super.c:1299
vfs_get_tree+0x92/0x2b0 fs/super.c:1759
do_new_mount+0x24a/0xa40 fs/namespace.c:3881
do_mount fs/namespace.c:4221 [inline]
__do_sys_mount fs/namespace.c:4432 [inline]
__se_sys_mount+0x317/0x410 fs/namespace.c:4409
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb8d278e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb8d05b4038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fb8d29b6160 RCX: 00007fb8d278e969
RDX: 0000200000000080 RSI: 00002000000000c0 RDI: 0000000000000000
RBP: 00007fb8d2810ab1 R08: 0000200000000340 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb8d29b6160 R15: 00007ffe7e429128
</TASK>
------------[ cut here ]------------
UBSAN: array-index-out-of-bounds in kernel/locking/qspinlock.h:68:9
index 2858 is out of range for type 'unsigned long[8]'
CPU: 0 UID: 0 PID: 10894 Comm: syz.5.1359 Not tainted 6.15.0-rc6-syzkaller-00346-g5723cc3450bc #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
ubsan_epilogue+0xa/0x40 lib/ubsan.c:231
__ubsan_handle_out_of_bounds+0xe9/0xf0 lib/ubsan.c:453
decode_tail kernel/locking/qspinlock.h:68 [inline]
__pv_queued_spin_lock_slowpath+0xaaf/0xb60 kernel/locking/qspinlock.c:285
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:572 [inline]
queued_spin_lock_slowpath+0x43/0x50 arch/x86/include/asm/qspinlock.h:51
queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
do_raw_spin_lock+0x21f/0x290 kernel/locking/spinlock_debug.c:116
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
_raw_spin_lock_irqsave+0xb3/0xf0 kernel/locking/spinlock.c:162
__percpu_counter_sum+0x2c/0x1e0 lib/percpu_counter.c:177
percpu_counter_sum include/linux/percpu_counter.h:105 [inline]
shmem_statfs+0x13d/0x2b0 mm/shmem.c:3815
statfs_by_dentry fs/statfs.c:66 [inline]
vfs_statfs+0x147/0x2d0 fs/statfs.c:90
ovl_check_namelen fs/overlayfs/super.c:388 [inline]
ovl_get_upper fs/overlayfs/super.c:506 [inline]
ovl_fill_super+0x788/0x35d0 fs/overlayfs/super.c:1392
vfs_get_super fs/super.c:1280 [inline]
get_tree_nodev+0xbb/0x150 fs/super.c:1299
vfs_get_tree+0x92/0x2b0 fs/super.c:1759
do_new_mount+0x24a/0xa40 fs/namespace.c:3881
do_mount fs/namespace.c:4221 [inline]
__do_sys_mount fs/namespace.c:4432 [inline]
__se_sys_mount+0x317/0x410 fs/namespace.c:4409
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb8d278e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb8d05b4038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fb8d29b6160 RCX: 00007fb8d278e969
RDX: 0000200000000080 RSI: 00002000000000c0 RDI: 0000000000000000
RBP: 00007fb8d2810ab1 R08: 0000200000000340 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb8d29b6160 R15: 00007ffe7e429128
</TASK>
---[ end trace ]---


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