On Thu, 18 Oct 2012, Bob Liu wrote:
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index a863af2..462d6ea 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1700,64 +1700,49 @@ static void release_pte_pages(pte_t *pte, pte_t *_pte)
> }
> }
>
> -static void release_all_pte_pages(pte_t *pte)
> -{
> - release_pte_pages(pte, pte + HPAGE_PMD_NR);
> -}
> -
> static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
> unsigned long address,
> pte_t *pte)
> {
> struct page *page;
> pte_t *_pte;
> - int referenced = 0, isolated = 0, none = 0;
> + int referenced = 0, isolated = 1, none = 0;
> for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
> _pte++, address += PAGE_SIZE) {
> pte_t pteval = *_pte;
> if (pte_none(pteval)) {
> if (++none <= khugepaged_max_ptes_none)
> continue;
> - else {
> - release_pte_pages(pte, _pte);
> + else
> goto out;
> - }
> }
> - if (!pte_present(pteval) || !pte_write(pteval)) {
> - release_pte_pages(pte, _pte);
> + if (!pte_present(pteval) || !pte_write(pteval))
> goto out;
> - }
> page = vm_normal_page(vma, address, pteval);
> - if (unlikely(!page)) {
> - release_pte_pages(pte, _pte);
> + if (unlikely(!page))
> goto out;
> - }
> +
> VM_BUG_ON(PageCompound(page));
> BUG_ON(!PageAnon(page));
> VM_BUG_ON(!PageSwapBacked(page));
>
> /* cannot use mapcount: can't collapse if there's a gup pin */
> - if (page_count(page) != 1) {
> - release_pte_pages(pte, _pte);
> + if (page_count(page) != 1)
> goto out;
> - }
> /*
> * We can do it before isolate_lru_page because the
> * page can't be freed from under us. NOTE: PG_lock
> * is needed to serialize against split_huge_page
> * when invoked from the VM.
> */
> - if (!trylock_page(page)) {
> - release_pte_pages(pte, _pte);
> + if (!trylock_page(page))
> goto out;
> - }
> /*
> * Isolate the page to avoid collapsing an hugepage
> * currently in use by the VM.
> */
> if (isolate_lru_page(page)) {
> unlock_page(page);
> - release_pte_pages(pte, _pte);
> goto out;
> }
> /* 0 stands for page_is_file_cache(page) == false */
> @@ -1770,11 +1755,11 @@ static int __collapse_huge_page_isolate(struct
> vm_area_struct *vma,
> mmu_notifier_test_young(vma->vm_mm, address))
> referenced = 1;
> }
> - if (unlikely(!referenced))
> - release_all_pte_pages(pte);
> - else
> - isolated = 1;
> + if (unlikely(!referenced)) {
> out:
Labels inside of conditionals are never good if they can be avoided and in
this case you can avoid it by doing
if (likely(referenced))
return 1;
out:
...
> + release_pte_pages(pte, _pte);
> + isolated = 0;
> + }
> return isolated;
> }
>
--
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