Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx> writes:
> On Friday, October 28, 2016 1:56 PM Huang, Ying wrote:
>> @@ -2016,10 +2021,12 @@ int page_trans_huge_mapcount(struct page *page, int *total_mapcount)
>> /* Racy check whether the huge page can be split */
>> bool can_split_huge_page(struct page *page)
>> {
>> - int extra_pins = 0;
>> + int extra_pins;
>>
>> /* Additional pins from radix tree */
>> - if (!PageAnon(page))
>> + if (PageAnon(page))
>> + extra_pins = PageSwapCache(page) ? HPAGE_PMD_NR : 0;
>> + else
>> extra_pins = HPAGE_PMD_NR;
>
> extra_pins is computed in this newly added helper.
>
>> return total_mapcount(page) == page_count(page) - extra_pins - 1;
>> }
>> @@ -2072,7 +2079,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
>> ret = -EBUSY;
>> goto out;
>> }
>> - extra_pins = 0;
>> + extra_pins = PageSwapCache(head) ? HPAGE_PMD_NR : 0;
>
> It is also computed at the call site, so can we fold them into one?
Sounds reasonable. I will add another argument to can_split_huge_page()
to return extra_pins, so we can avoid duplicated code and calculation.
Best Regards,
Huang, Ying
>> mapping = NULL;
>> anon_vma_lock_write(anon_vma);
>> } else {
>> --
>> 2.9.3
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