syzbot

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BUG: KCSAN: data-race in pcpu_alloc / pcpu_block_update_hint_alloc

read-write to 0xffffffff870ca9b4 of 4 bytes by task 2630 on cpu 1:
 pcpu_update_empty_pages mm/percpu.c:606 [inline]
 pcpu_block_update_hint_alloc+0x61e/0x6e0 mm/percpu.c:919
 pcpu_alloc_area+0x4dc/0x500 mm/percpu.c:1254
 pcpu_alloc+0x44e/0x1040 mm/percpu.c:1813
 __alloc_percpu_gfp+0x22/0x30 mm/percpu.c:1937
 bpf_map_alloc_percpu+0xbd/0x200 kernel/bpf/syscall.c:481
 prealloc_init kernel/bpf/hashtab.c:342 [inline]
 htab_map_alloc+0x76e/0xc00 kernel/bpf/hashtab.c:554
 find_and_alloc_map kernel/bpf/syscall.c:131 [inline]
 map_create+0x38a/0x6f0 kernel/bpf/syscall.c:1102
 __sys_bpf+0x28c/0x620 kernel/bpf/syscall.c:4935
 __do_sys_bpf kernel/bpf/syscall.c:5057 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5055 [inline]
 __x64_sys_bpf+0x3f/0x50 kernel/bpf/syscall.c:5055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff870ca9b4 of 4 bytes by task 2628 on cpu 0:
 pcpu_alloc+0x9c6/0x1040 mm/percpu.c:1877
 __alloc_percpu_gfp+0x22/0x30 mm/percpu.c:1937
 bpf_map_alloc_percpu+0xbd/0x200 kernel/bpf/syscall.c:481
 prealloc_init kernel/bpf/hashtab.c:342 [inline]
 htab_map_alloc+0x76e/0xc00 kernel/bpf/hashtab.c:554
 find_and_alloc_map kernel/bpf/syscall.c:131 [inline]
 map_create+0x38a/0x6f0 kernel/bpf/syscall.c:1102
 __sys_bpf+0x28c/0x620 kernel/bpf/syscall.c:4935
 __do_sys_bpf kernel/bpf/syscall.c:5057 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5055 [inline]
 __x64_sys_bpf+0x3f/0x50 kernel/bpf/syscall.c:5055
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000014 -> 0x0000000c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2628 Comm: syz-executor.1 Not tainted 6.0.0-rc7-syzkaller-00250-ga962b54e162c-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
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