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SubjectRe: [Patch v3 7/7] mm/hugetlb: take the free hpage during the iteration directly
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On 8/30/20 7:23 PM, Wei Yang wrote:
> Function dequeue_huge_page_node_exact() iterates the free list and
> return the first valid free hpage.
>
> Instead of break and check the loop variant, we could return in the loop
> directly. This could reduce some redundant check.
>
> Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com>
> ---
> mm/hugetlb.c | 20 ++++++++------------
> 1 file changed, 8 insertions(+), 12 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 7b3357c1dcec..709be7ab65af 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1040,21 +1040,17 @@ static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid)
> if (nocma && is_migrate_cma_page(page))
> continue;
>
> - if (!PageHWPoison(page))
> + if (PageHWPoison(page))
> break;

Previously, when encountering a PageHWPoison(page) the loop would continue
and check the next page in the list. It now breaks the loop and returns
NULL. Is not this a change in behavior? Perhaps you want to change that
break to a continue. Or, restructure in some other way.
--
Mike Kravetz

> +
> + list_move(&page->lru, &h->hugepage_activelist);
> + set_page_refcounted(page);
> + h->free_huge_pages--;
> + h->free_huge_pages_node[nid]--;
> + return page;
> }
>
> - /*
> - * if 'non-isolated free hugepage' not found on the list,
> - * the allocation fails.
> - */
> - if (&h->hugepage_freelists[nid] == &page->lru)
> - return NULL;
> - list_move(&page->lru, &h->hugepage_activelist);
> - set_page_refcounted(page);
> - h->free_huge_pages--;
> - h->free_huge_pages_node[nid]--;
> - return page;
> + return NULL;
> }
>
> static struct page *dequeue_huge_page_nodemask(struct hstate *h, gfp_t gfp_mask, int nid,
>

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