THP splitting's unmap_page() only sets TTU_SPLIT_FREEZE when PageAnon,
and migration entries are only inserted when TTU_MIGRATION (unused here)
or TTU_SPLIT_FREEZE is set: so it's just a waste of time for remap_page()
to search for migration entries to remove when !PageAnon.
Fixes: baa355fd3314 ("thp: file pages support for split_huge_page()")
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
---
mm/huge_memory.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 305f709a7aca..e4a83e310452 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2354,6 +2354,7 @@ static void unmap_page(struct page *page)
VM_BUG_ON_PAGE(!PageHead(page), page);
+ /* If TTU_SPLIT_FREEZE is ever extended to file, update remap_page() */
if (PageAnon(page))
ttu_flags |= TTU_SPLIT_FREEZE;
@@ -2368,6 +2369,10 @@ static void unmap_page(struct page *page)
static void remap_page(struct page *page, unsigned int nr)
{
int i;
+
+ /* If TTU_SPLIT_FREEZE is ever extended to file, remove this check */
+ if (!PageAnon(page))
+ return;
if (PageTransHuge(page)) {
remove_migration_ptes(page, page, true);
} else {
--
2.32.0.rc0.204.g9fa02ecfa5-goog
