syzbot

==================================================================
BUG: KCSAN: data-race in pcpu_alloc / pcpu_free_area

read-write to 0xffffffff86ef831c of 4 bytes by task 3105 on cpu 1:
 pcpu_update_empty_pages mm/percpu.c:602 [inline]
 pcpu_block_update_hint_free mm/percpu.c:1044 [inline]
 pcpu_free_area+0x4e2/0x570 mm/percpu.c:1302
 free_percpu+0x1c6/0xb20 mm/percpu.c:2303
 xt_percpu_counter_free+0x63/0x70 net/netfilter/x_tables.c:1950
 cleanup_entry+0x18a/0x1b0 net/ipv6/netfilter/ip6_tables.c:671
 __do_replace+0x473/0x580 net/ipv6/netfilter/ip6_tables.c:1099
 do_replace net/ipv6/netfilter/ip6_tables.c:1154 [inline]
 do_ip6t_set_ctl+0x1503/0x17f0 net/ipv6/netfilter/ip6_tables.c:1636
 nf_setsockopt+0x18d/0x1b0 net/netfilter/nf_sockopt.c:101
 ipv6_setsockopt+0x11c/0x130 net/ipv6/ipv6_sockglue.c:1005
 tcp_setsockopt+0x90/0xa0 net/ipv4/tcp.c:3704
 sock_common_setsockopt+0x61/0x70 net/core/sock.c:3711
 do_sock_setsockopt net/socket.c:2311 [inline]
 __sys_setsockopt+0x1d4/0x240 net/socket.c:2334
 __do_sys_setsockopt net/socket.c:2343 [inline]
 __se_sys_setsockopt net/socket.c:2340 [inline]
 __x64_sys_setsockopt+0x66/0x80 net/socket.c:2340
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffffffff86ef831c of 4 bytes by task 3119 on cpu 0:
 pcpu_alloc+0x9bc/0x10b0 mm/percpu.c:1868
 __alloc_percpu+0x24/0x30 mm/percpu.c:1943
 mm_alloc_cid include/linux/mm_types.h:1142 [inline]
 mm_init+0x461/0x6d0 kernel/fork.c:1304
 dup_mm kernel/fork.c:1688 [inline]
 copy_mm+0x11c/0xf50 kernel/fork.c:1740
 copy_process+0x1002/0x20a0 kernel/fork.c:2502
 kernel_clone+0x169/0x560 kernel/fork.c:2907
 __do_sys_clone kernel/fork.c:3050 [inline]
 __se_sys_clone kernel/fork.c:3034 [inline]
 __x64_sys_clone+0xe8/0x120 kernel/fork.c:3034
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000003 -> 0x00000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3119 Comm: syz-executor.4 Not tainted 6.7.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
==================================================================