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BUG: KCSAN: data-race in pcpu_alloc / pcpu_block_update_hint_alloc

read-write to 0xffffffff884054dc of 4 bytes by task 7815 on cpu 0:
 pcpu_update_empty_pages mm/percpu.c:602 [inline]
 pcpu_block_update_hint_alloc+0x5db/0x6a0 mm/percpu.c:923
 pcpu_alloc_area+0x49f/0x4d0 mm/percpu.c:1258
 pcpu_alloc+0x4b3/0x10d0 mm/percpu.c:1808
 __alloc_percpu+0x24/0x30 mm/percpu.c:1943
 xt_percpu_counter_alloc+0x72/0x110 net/netfilter/x_tables.c:1931
 find_check_entry net/ipv6/netfilter/ip6_tables.c:545 [inline]
 translate_table+0x9b1/0x1040 net/ipv6/netfilter/ip6_tables.c:733
 do_replace net/ipv6/netfilter/ip6_tables.c:1154 [inline]
 do_ip6t_set_ctl+0x7cc/0x8c0 net/ipv6/netfilter/ip6_tables.c:1644
 nf_setsockopt+0x195/0x1b0 net/netfilter/nf_sockopt.c:101
 ipv6_setsockopt+0x126/0x140 net/ipv6/ipv6_sockglue.c:999
 tcp_setsockopt+0x93/0xb0 net/ipv4/tcp.c:3737
 sock_common_setsockopt+0x64/0x80 net/core/sock.c:3727
 do_sock_setsockopt net/socket.c:2311 [inline]
 __sys_setsockopt+0x1d8/0x250 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
 x64_sys_call+0x1159/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:55
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff884054dc of 4 bytes by task 4957 on cpu 1:
 pcpu_alloc+0x9aa/0x10d0 mm/percpu.c:1868
 __alloc_percpu+0x24/0x30 mm/percpu.c:1943
 mm_alloc_cid include/linux/mm_types.h:1175 [inline]
 mm_init+0x462/0x6d0 kernel/fork.c:1301
 dup_mm kernel/fork.c:1685 [inline]
 copy_mm+0x11d/0x1040 kernel/fork.c:1737
 copy_process+0xee1/0x1f80 kernel/fork.c:2390
 kernel_clone+0x16a/0x570 kernel/fork.c:2797
 __do_sys_clone kernel/fork.c:2940 [inline]
 __se_sys_clone kernel/fork.c:2924 [inline]
 __x64_sys_clone+0xe8/0x120 kernel/fork.c:2924
 x64_sys_call+0x23cb/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:57
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000050 -> 0x0000004f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4957 Comm: syz-executor.4 Not tainted 6.9.0-rc7-syzkaller-00012-gdccb07f2914c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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