From: Matthew Wilcox (Oracle) <willy@infradead.org>
Date: Sat, 15 Aug 2020 23:28:51 +0000 (-0400)
Subject: mm/vmscan: Optimise shrink_page_list for non-PMD-sized folios
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=343b288834e84d0b175b20b4f48277bc33260986;p=linux.git

mm/vmscan: Optimise shrink_page_list for non-PMD-sized folios

A large folio which is smaller than a PMD does not need to do the extra
work in try_to_unmap() of trying to split a PMD entry.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---

diff --git a/mm/vmscan.c b/mm/vmscan.c
index d15a9f08caab7..8243437e5c5f3 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1765,7 +1765,8 @@ retry:
 			enum ttu_flags flags = TTU_BATCH_FLUSH;
 			bool was_swapbacked = PageSwapBacked(page);
 
-			if (unlikely(PageTransHuge(page)))
+			if (PageTransHuge(page) &&
+					thp_order(page) >= HPAGE_PMD_ORDER)
 				flags |= TTU_SPLIT_HUGE_PMD;
 
 			try_to_unmap(folio, flags);