Hello,
On Sun, Jul 18, 2021 at 07:17:52PM -0700, Yury Norov wrote:
> bitmap_next_clear_region() calls find_next_zero_bit() and find_next_bit()
> sequentially to find a range of clear bits. In case of pcpu_is_populated()
> there's a chance to return earlier if bitmap has all bits set.
>
> Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>
> ---
> mm/percpu.c | 15 ++++++++-------
> 1 file changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/mm/percpu.c b/mm/percpu.c
> index 7f2e0151c4e2..25461571dcc5 100644
> --- a/mm/percpu.c
> +++ b/mm/percpu.c
> @@ -1071,17 +1071,18 @@ static void pcpu_block_update_hint_free(struct pcpu_chunk *chunk, int bit_off,
> static bool pcpu_is_populated(struct pcpu_chunk *chunk, int bit_off, int bits,
> int *next_off)
> {
> - unsigned int page_start, page_end, rs, re;
> + unsigned int start, end;
>
> - page_start = PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE);
> - page_end = PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE);
> + start = PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE);
> + end = PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE);
>
> - rs = page_start;
> - bitmap_next_clear_region(chunk->populated, &rs, &re, page_end);
> - if (rs >= page_end)
> + start = find_next_zero_bit(chunk->populated, end, start);
> + if (start >= end)
> return true;
>
> - *next_off = re * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE;
> + end = find_next_bit(chunk->populated, end, start + 1);
> +
> + *next_off = end * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE;
> return false;
> }
>
> --
> 2.30.2
>
Sorry for the delay.
Acked-by: Dennis Zhou <dennis@xxxxxxxxxx>
Thanks,
Dennis
