From d965432234db94ee8e185f8fd8e3181bed7459fd Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Fri, 15 Jan 2016 16:54:43 -0800 Subject: [PATCH] thp: increase split_huge_page() success rate 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 Cc: Sasha Levin Acked-by: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index a0b910a0c2cb..882b04449904 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -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); -- 2.20.1