thp: increase split_huge_page() success rate (d9654322) · Commits · 戴 / test

During freeze_page(), we remove the page from rmap. It munlocks the page if it was mlocked. clear_page_mlock() uses thelru cache, which temporary pins the page. Let's drain the lru cache before checking page's count vs. mapcount. The change makes mlocked page split on first attempt, if it was not pinned by somebody else. Signed-off-by:

Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Sasha Levin <sasha.levin@oracle.com> Acked-by:

Vlastimil Babka <vbabka@suse.cz> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

mm/huge_memory.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -3201,6 +3201,7 @@ int split_huge_page_to_list(struct page page, struct list_head list)
		struct page *head = compound_head(page);
		struct anon_vma *anon_vma;
		int count, mapcount, ret;
		bool mlocked;

		VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
		VM_BUG_ON_PAGE(!PageAnon(page), page);
		@@ -3231,9 +3232,14 @@ int split_huge_page_to_list(struct page page, struct list_head list)
		goto out_unlock;
		}

		mlocked = PageMlocked(page);
		freeze_page(anon_vma, head);
		VM_BUG_ON_PAGE(compound_mapcount(head), head);

		/* Make sure the page is not on per-CPU pagevec as it takes pin */
		if (mlocked)
		lru_add_drain();

		/* Prevent deferred_split_scan() touching ->_count */
		spin_lock(&split_queue_lock);
		count = page_count(head);

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