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BUG: KCSAN: data-race in pcpu_alloc / pcpu_free_area

read-write to 0xffffffff8840949c of 4 bytes by task 20792 on cpu 0:
 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+0x1c6/0xb30 mm/percpu.c:2303
 xt_percpu_counter_free+0x63/0x80 net/netfilter/x_tables.c:1951
 cleanup_entry+0x186/0x1b0 net/ipv4/netfilter/ip_tables.c:654
 __do_replace+0x46e/0x570 net/ipv4/netfilter/ip_tables.c:1082
 do_replace net/ipv4/netfilter/ip_tables.c:1141 [inline]
 do_ipt_set_ctl+0x811/0x8b0 net/ipv4/netfilter/ip_tables.c:1635
 nf_setsockopt+0x195/0x1b0 net/netfilter/nf_sockopt.c:101
 ip_setsockopt+0xea/0x100 net/ipv4/ip_sockglue.c:1424
 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 0xffffffff8840949c of 4 bytes by task 22227 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
 mm_alloc+0x81/0xa0 kernel/fork.c:1335
 bprm_mm_init fs/exec.c:374 [inline]
 alloc_bprm+0x1be/0x560 fs/exec.c:1588
 do_execveat_common+0x138/0x7d0 fs/exec.c:1938
 do_execve fs/exec.c:2061 [inline]
 __do_sys_execve fs/exec.c:2137 [inline]
 __se_sys_execve fs/exec.c:2132 [inline]
 __x64_sys_execve+0x5a/0x70 fs/exec.c:2132
 x64_sys_call+0x1354/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:60
 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: 0x0000002b -> 0x0000002c

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 22227 Comm: syz-fuzzer Tainted: G        W          6.9.0-syzkaller-01768-ga5131c3fdf26 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
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