[syzbot] [cgroups?] WARNING in css_rstat_flush

[syzbot <syzbot+7a605e85e5b5a7e4a5e3@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    90b83efa6701 Merge tag 'bpf-next-6.16' of git://git.kernel..
git tree:       bpf
console output: https://syzkaller.appspot.com/x/log.txt?x=1034f482580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=262b2977ef00756b
dashboard link: https://syzkaller.appspot.com/bug?extid=7a605e85e5b5a7e4a5e3
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d5357fcb09e6/disk-90b83efa.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dcb0f12e4d5a/vmlinux-90b83efa.xz
kernel image: https://storage.googleapis.com/syzbot-assets/278fcadd7519/bzImage-90b83efa.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7a605e85e5b5a7e4a5e3@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 0 PID: 10 at kernel/cgroup/rstat.c:302 css_rstat_updated_list kernel/cgroup/rstat.c:302 [inline]
WARNING: CPU: 0 PID: 10 at kernel/cgroup/rstat.c:302 css_rstat_flush+0x76f/0x1fa0 kernel/cgroup/rstat.c:413
Modules linked in:
CPU: 0 UID: 0 PID: 10 Comm: kworker/0:1 Not tainted 6.15.0-syzkaller-g90b83efa6701 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: cgroup_destroy css_free_rwork_fn
RIP: 0010:css_rstat_updated_list kernel/cgroup/rstat.c:302 [inline]
RIP: 0010:css_rstat_flush+0x76f/0x1fa0 kernel/cgroup/rstat.c:413
Code: df 80 3c 08 00 74 08 4c 89 e7 e8 4c 3a 6a 00 49 8b 1c 24 48 3b 5c 24 38 74 22 e8 9c 1c 07 00 e9 72 ff ff ff e8 92 1c 07 00 90 <0f> 0b 90 eb bd e8 87 1c 07 00 45 31 e4 e9 bb 03 00 00 e8 7a 1c 07
RSP: 0018:ffffc900000f7780 EFLAGS: 00010093
RAX: ffffffff81b8de5e RBX: ffffffff99c36880 RCX: ffff88801d2b1e00
RDX: 0000000000000000 RSI: ffffffff8be263a0 RDI: ffffffff8be26360
RBP: ffffc900000f79b8 R08: ffffffff8fa0b1b7 R09: 1ffffffff1f41636
R10: dffffc0000000000 R11: fffffbfff1f41637 R12: ffff8880b8642758
R13: ffffffff99c36880 R14: ffffffff8db91c60 R15: ffff888125c66008
FS:  0000000000000000(0000) GS:ffff888125c66000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f350fc65760 CR3: 0000000032e5c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 css_rstat_exit+0xa9/0x320 kernel/cgroup/rstat.c:479
 css_free_rwork_fn+0x8b/0xc50 kernel/cgroup/cgroup.c:5449
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


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