[PATCH v13 131/137] mm/vmscan: Free non-shmem THPs without splitting them

Matthew Wilcox (Oracle)
2021-07-12T04:18:11Z

We have to allocate memory in order to split a file-backed page,
so it's not a good idea to split them. It also doesn't work for XFS
because pages have an extra reference count from page_has_private() and
split_huge_page() expects that reference to have already been removed.
Unfortunately, we still have to split shmem THPs because we can't handle
swapping out an entire THP yet.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
mm/vmscan.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7a2f25b904d9..8b17e46dbf32 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1470,8 +1470,8 @@ static unsigned int shrink_page_list(struct list_head *page_list,
/* Adding to swap updated mapping */
mapping = page_mapping(page);
}
- } else if (unlikely(PageTransHuge(page))) {
- /* Split file THP */
+ } else if (PageSwapBacked(page) && PageTransHuge(page)) {
+ /* Split shmem THP */
if (split_huge_page_to_list(page, page_list))
goto keep_locked;
}
--
2.30.2