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SubjectRe: [Patch v3 7/7] mm/hugetlb: take the free hpage during the iteration directly
On Mon, Aug 31, 2020 at 04:06:54PM -0700, Mike Kravetz wrote:
>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.

Shame on me. You are right. I should change it to continue.

Andrew,

Sorry for the inconvenience.

>--
>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,
>>

--
Wei Yang
Help you, Help me

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