[syzbot] [kernel?] WARNING: locking bug in collect_percpu_times

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2a8120d7b482 Merge tag 's390-6.10-2' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=145dd452980000
kernel config: https://syzkaller.appspot.com/x/.config?x=5dd4fde1337a9e18
dashboard link: https://syzkaller.appspot.com/bug?extid=97f26f162079653e77b8
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-2a8120d7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/78c72ae6bdaf/vmlinux-2a8120d7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/99dbb805b738/bzImage-2a8120d7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+97f26f...@syzkaller.appspotmail.com

------------[ cut here ]------------
Looking for class "->pcpu, cpu)->seq" with key __key.9, but found a different class "&per_cpu_ptr(group->pcpu, cpu)->seq" with the same key
WARNING: CPU: 3 PID: 57 at kernel/locking/lockdep.c:932 look_up_lock_class+0x133/0x140 kernel/locking/lockdep.c:932
Modules linked in:
CPU: 3 PID: 57 Comm: kworker/3:1 Not tainted 6.9.0-syzkaller-10713-g2a8120d7b482 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: events psi_avgs_work
RIP: 0010:look_up_lock_class+0x133/0x140 kernel/locking/lockdep.c:932
Code: c7 c7 a0 b5 2c 8b e8 3c d2 72 f6 90 0f 0b 90 90 90 31 db eb be c6 05 43 e6 ed 04 01 90 48 c7 c7 c0 b8 2c 8b e8 1e d2 72 f6 90 <0f> 0b 90 90 e9 62 ff ff ff 0f 1f 40 00 90 90 90 90 90 90 90 90 90
RSP: 0000:ffffc9000077f6f8 EFLAGS: 00010086
RAX: 0000000000000000 RBX: ffffffff94205020 RCX: ffffffff81510229
RDX: ffff888019080000 RSI: ffffffff81510236 RDI: 0000000000000001
RBP: ffffffff92e32ba0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 20676e696b6f6f4c R12: ffffe8ffad14b848
R13: 0000000000000000 R14: 0000000000000000 R15: ffffffff94adaba0
FS: 0000000000000000(0000) GS:ffff88802c300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000ee176000 CR3: 0000000026c9c000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
register_lock_class+0xb1/0x1230 kernel/locking/lockdep.c:1284
__lock_acquire+0x111/0x3b30 kernel/locking/lockdep.c:5014
lock_acquire kernel/locking/lockdep.c:5754 [inline]
lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
seqcount_lockdep_reader_access include/linux/seqlock.h:72 [inline]
get_recent_times kernel/sched/psi.c:261 [inline]
collect_percpu_times+0x6cf/0xb70 kernel/sched/psi.c:359
psi_avgs_work+0x9c/0x210 kernel/sched/psi.c:566
process_one_work+0x958/0x1ad0 kernel/workqueue.c:3231
process_scheduled_works kernel/workqueue.c:3312 [inline]
worker_thread+0x6c8/0xf70 kernel/workqueue.c:3393
kthread+0x2c1/0x3a0 kernel/kthread.c:389
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>


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[Thomas Gleixner]

On Sat, May 25 2024 at 14:52, syzbot wrote:
> HEAD commit: 2a8120d7b482 Merge tag 's390-6.10-2' of git://git.kernel.o..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=145dd452980000
> kernel config: https://syzkaller.appspot.com/x/.config?x=5dd4fde1337a9e18
> dashboard link: https://syzkaller.appspot.com/bug?extid=97f26f162079653e77b8
> compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> userspace arch: i386
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-2a8120d7.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/78c72ae6bdaf/vmlinux-2a8120d7.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/99dbb805b738/bzImage-2a8120d7.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+97f26f...@syzkaller.appspotmail.com
>
> ------------[ cut here ]------------
> Looking for class "->pcpu, cpu)->seq" with key __key.9, but found a different class "&per_cpu_ptr(group->pcpu, cpu)->seq" with the same key

This is a pattern I've seen in quite some recent syzbot reports where
the class string is a subset of the recorded string.

I have no idea how that can happen, but it smells like data corruption
of some sort.