Messages in this thread | | | Date | Wed, 4 Aug 2021 17:22:57 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCH 2/3] mm: free zapped tail pages when splitting isolated thp |
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On Sat, Jul 31, 2021 at 12:39:37AM -0600, Yu Zhao wrote: > @@ -2506,6 +2508,25 @@ static void __split_huge_page(struct page *page, struct list_head *list, > continue; > unlock_page(subpage); > > + /* > + * If a tail page has only two references left, one inherited > + * from the isolation of its head and the other from > + * lru_add_page_tail() which we are about to drop, it means this > + * tail page was concurrently zapped. Then we can safely free it > + * and save page reclaim or migration the trouble of trying it. > + */ > + if (list && page_ref_freeze(subpage, 2)) { > + VM_BUG_ON_PAGE(PageLRU(subpage), subpage); > + VM_BUG_ON_PAGE(PageCompound(subpage), subpage); > + VM_BUG_ON_PAGE(page_mapped(subpage), subpage); > + > + ClearPageActive(subpage); > + ClearPageUnevictable(subpage);
Why touch PG_Active/PG_Unevictable?
> + list_move(&subpage->lru, &pages_to_free); > + nr_pages_to_free++; > + continue; > + } > +
-- Kirill A. Shutemov
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