[syzbot] [net?] net-next test error: WARNING in register_net_sysctl

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8b33485128ad net: skbuff: update comment about pfmemalloc ..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=127f776e280000
kernel config: https://syzkaller.appspot.com/x/.config?x=8bc832f563d8bf38
dashboard link: https://syzkaller.appspot.com/bug?extid=a5e719ac7c268e414c95
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/dede64e71bac/disk-8b334851.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/641ec7bf48a8/vmlinux-8b334851.xz
kernel image: https://storage.googleapis.com/syzbot-assets/155dbbd26fa3/bzImage-8b334851.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a5e719...@syzkaller.appspotmail.com

------------[ cut here ]------------
sysctl net/ipv4/ipfrag_low_thresh: data points to kernel global data: ipfrag_low_thresh_unused
WARNING: CPU: 0 PID: 5005 at net/sysctl_net.c:155 ensure_safe_net_sysctl net/sysctl_net.c:155 [inline]
WARNING: CPU: 0 PID: 5005 at net/sysctl_net.c:155 register_net_sysctl+0x207/0x3c0 net/sysctl_net.c:167
Modules linked in:
CPU: 0 PID: 5005 Comm: syz-executor.0 Not tainted 6.4.0-rc1-syzkaller-00234-g8b33485128ad #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/28/2023
RIP: 0010:ensure_safe_net_sysctl net/sysctl_net.c:155 [inline]
RIP: 0010:register_net_sysctl+0x207/0x3c0 net/sysctl_net.c:167
Code: 8b 43 f4 48 89 f8 48 c1 e8 03 80 3c 28 00 0f 85 a9 01 00 00 48 8b 53 ec 4c 89 e9 4c 89 fe 48 c7 c7 c0 01 85 8b e8 59 61 81 f7 <0f> 0b 48 89 d8 48 c1 e8 03 0f b6 14 28 48 89 d8 83 e0 07 83 c0 01
RSP: 0018:ffffc90003a3fbf8 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff88802a554454 RCX: 0000000000000000
RDX: ffff888028aebb80 RSI: ffffffff814c03e7 RDI: 0000000000000001
RBP: dffffc0000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff88802a554448
R13: ffffffff8b850040 R14: 0000000000000000 R15: ffffffff8b694ce0
FS: 0000555556d45400(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005592b998eff0 CR3: 0000000070817000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
ip4_frags_ns_ctl_register net/ipv4/ip_fragment.c:618 [inline]
ipv4_frags_init_net net/ipv4/ip_fragment.c:689 [inline]
ipv4_frags_init_net+0x269/0x430 net/ipv4/ip_fragment.c:660
ops_init+0xb9/0x6b0 net/core/net_namespace.c:136
setup_net+0x5d1/0xc50 net/core/net_namespace.c:339
copy_net_ns+0x4ee/0x8e0 net/core/net_namespace.c:491
create_new_namespaces+0x3f6/0xb20 kernel/nsproxy.c:110
unshare_nsproxy_namespaces+0xc1/0x1f0 kernel/nsproxy.c:228
ksys_unshare+0x449/0x920 kernel/fork.c:3444
__do_sys_unshare kernel/fork.c:3515 [inline]
__se_sys_unshare kernel/fork.c:3513 [inline]
__x64_sys_unshare+0x31/0x40 kernel/fork.c:3513
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f8868a8d727
Code: 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 10 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc80abab68 EFLAGS: 00000202 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007ffc80abb1a8 RCX: 00007f8868a8d727
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000040000000
RBP: 00000000ffffffff R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003
R13: 00007ffc80abac40 R14: 00007f8868bac9d8 R15: 000000000000000c
</TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the bug is already fixed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to change bug's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the bug is a duplicate of another bug, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup