[moderation] [cgroups?] [mm?] general protection fault in mod_objcg_mlstate

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d9104cec3e8f Merge tag 'bpf-next-6.17' of git://git.kernel..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1217d2f0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ac0888b9ad46cd69
dashboard link: https://syzkaller.appspot.com/bug?extid=77fd5b33825fa2cab74f
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
CC: [ak...@linux-foundation.org cgr...@vger.kernel.org han...@cmpxchg.org linux-...@vger.kernel.org linu...@kvack.org mho...@kernel.org muchu...@linux.dev net...@vger.kernel.org roman.g...@linux.dev shakee...@linux.dev]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ed717a4a878a/disk-d9104cec.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/08035d746f31/vmlinux-d9104cec.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7b5bf8caca80/bzImage-d9104cec.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+77fd5b...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000187: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000c38-0x0000000000000c3f]
CPU: 1 UID: 0 PID: 29406 Comm: kworker/u8:19 Not tainted 6.16.0-syzkaller-06574-gd9104cec3e8f #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: kvfree_rcu_reclaim kfree_rcu_work
RIP: 0010:mem_cgroup_lruvec include/linux/memcontrol.h:709 [inline]
RIP: 0010:account_slab_nmi_safe mm/memcontrol.c:2545 [inline]
RIP: 0010:mod_objcg_mlstate+0x138/0x260 mm/memcontrol.c:2558
Code: 00 4c 89 e0 48 c1 e8 03 0f b6 04 28 84 c0 0f 85 0b 01 00 00 49 63 04 24 4c 8d 24 c5 00 00 00 00 4d 01 ec 4c 89 e0 48 c1 e8 03 <80> 3c 28 00 74 08 4c 89 e7 e8 ca 51 f7 ff 4d 8b 24 24 49 83 c4 48
RSP: 0018:ffffc9000cfb7758 EFLAGS: 00010206
RAX: 0000000000000187 RBX: ffffffff822b80b4 RCX: 42d26e8ae77b4200
RDX: 0000000000000000 RSI: ffffffff8db65e8b RDI: ffffffff8be30a00
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffffff822b80b4
R10: dffffc0000000000 R11: ffffed100f83c8f4 R12: 0000000000000c3b
R13: 0000000000000c3b R14: ffff8880b873b4c0 R15: ffff88813fffb400
FS: 0000000000000000(0000) GS:ffff888125d80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f390ed0c967 CR3: 000000004461e000 CR4: 00000000003526f0
Call Trace:
<TASK>
drain_obj_stock+0x23e/0x3c0 mm/memcontrol.c:2994
refill_obj_stock+0x247/0x850 mm/memcontrol.c:3042
__memcg_slab_free_hook+0x127/0x3d0 mm/memcontrol.c:3217
memcg_slab_free_hook mm/slub.c:2206 [inline]
slab_free_bulk mm/slub.c:4661 [inline]
kmem_cache_free_bulk+0x46e/0x520 mm/slub.c:5246
kfree_bulk include/linux/slab.h:794 [inline]
kvfree_rcu_bulk+0xe5/0x1f0 mm/slab_common.c:1516
kfree_rcu_work+0xed/0x170 mm/slab_common.c:1594
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>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:mem_cgroup_lruvec include/linux/memcontrol.h:709 [inline]
RIP: 0010:account_slab_nmi_safe mm/memcontrol.c:2545 [inline]
RIP: 0010:mod_objcg_mlstate+0x138/0x260 mm/memcontrol.c:2558
Code: 00 4c 89 e0 48 c1 e8 03 0f b6 04 28 84 c0 0f 85 0b 01 00 00 49 63 04 24 4c 8d 24 c5 00 00 00 00 4d 01 ec 4c 89 e0 48 c1 e8 03 <80> 3c 28 00 74 08 4c 89 e7 e8 ca 51 f7 ff 4d 8b 24 24 49 83 c4 48
RSP: 0018:ffffc9000cfb7758 EFLAGS: 00010206
RAX: 0000000000000187 RBX: ffffffff822b80b4 RCX: 42d26e8ae77b4200
RDX: 0000000000000000 RSI: ffffffff8db65e8b RDI: ffffffff8be30a00
RBP: dffffc0000000000 R08: 0000000000000000 R09: ffffffff822b80b4
R10: dffffc0000000000 R11: ffffed100f83c8f4 R12: 0000000000000c3b
R13: 0000000000000c3b R14: ffff8880b873b4c0 R15: ffff88813fffb400
FS: 0000000000000000(0000) GS:ffff888125d80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f390ed0c967 CR3: 000000004461e000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: 00 4c 89 e0 add %cl,-0x20(%rcx,%rcx,4)
4: 48 c1 e8 03 shr $0x3,%rax
8: 0f b6 04 28 movzbl (%rax,%rbp,1),%eax
c: 84 c0 test %al,%al
e: 0f 85 0b 01 00 00 jne 0x11f
14: 49 63 04 24 movslq (%r12),%rax
18: 4c 8d 24 c5 00 00 00 lea 0x0(,%rax,8),%r12
1f: 00
20: 4d 01 ec add %r13,%r12
23: 4c 89 e0 mov %r12,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 4c 89 e7 mov %r12,%rdi
33: e8 ca 51 f7 ff call 0xfff75202
38: 4d 8b 24 24 mov (%r12),%r12
3c: 49 83 c4 48 add $0x48,%r12


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.