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

read-write to 0xffffffff883db4dc of 4 bytes by task 21879 on cpu 1:
 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_gfp+0x26/0x30 mm/percpu.c:1930
 bpf_map_alloc_percpu+0xab/0x200 kernel/bpf/syscall.c:466
 prealloc_init+0x19f/0x470 kernel/bpf/hashtab.c:338
 htab_map_alloc+0x637/0x8f0 kernel/bpf/hashtab.c:573
 map_create+0x83c/0xb90 kernel/bpf/syscall.c:1320
 __sys_bpf+0x667/0x7a0 kernel/bpf/syscall.c:5613
 __do_sys_bpf kernel/bpf/syscall.c:5738 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5736 [inline]
 __x64_sys_bpf+0x43/0x50 kernel/bpf/syscall.c:5736
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

read to 0xffffffff883db4dc of 4 bytes by task 17697 on cpu 0:
 pcpu_alloc+0x9aa/0x10d0 mm/percpu.c:1868
 __alloc_percpu_gfp+0x26/0x30 mm/percpu.c:1930
 __percpu_counter_init_many+0x3c/0x1f0 lib/percpu_counter.c:164
 mm_init+0x59d/0x6d0 kernel/fork.c:1303
 dup_mm kernel/fork.c:1684 [inline]
 copy_mm+0x120/0x1070 kernel/fork.c:1736
 copy_process+0xee1/0x1f80 kernel/fork.c:2389
 kernel_clone+0x16a/0x570 kernel/fork.c:2796
 __do_sys_clone kernel/fork.c:2939 [inline]
 __se_sys_clone kernel/fork.c:2923 [inline]
 __x64_sys_clone+0xe8/0x120 kernel/fork.c:2923
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

value changed: 0x00000005 -> 0xfffffffd

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 17697 Comm: syz-executor.4 Tainted: G        W          6.9.0-rc2-syzkaller-00080-gc85af715cac0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
==================================================================