mm/rmap: move SetPageAnonExclusive() out of page_move_anon_rmap()

Patch series "mm/rmap: convert page_move_anon_rmap() to
folio_move_anon_rmap()".

Convert page_move_anon_rmap() to folio_move_anon_rmap(), letting the
callers handle PageAnonExclusive.  I'm including cleanup patch #3 because
it fits into the picture and can be done cleaner by the conversion.


This patch (of 3):

Let's move it into the caller: there is a difference between whether an
anon folio can only be mapped by one process (e.g., into one VMA), and
whether it is truly exclusive (e.g., no references -- including GUP --
from other processes).

Further, for large folios the page might not actually be pointing at the
head page of the folio, so it better be handled in the caller.  This is a
preparation for converting page_move_anon_rmap() to consume a folio.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Reviewed-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Vishal Moola (Oracle) <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 3 insertions, 1 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 2878e0e6bac5..35d924f74972 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5652,8 +5652,10 @@ retry_avoidcopy:
 	 * owner and can reuse this page.
 	 */
 	if (folio_mapcount(old_folio) == 1 && folio_test_anon(old_folio)) {
-		if (!PageAnonExclusive(&old_folio->page))
+		if (!PageAnonExclusive(&old_folio->page)) {
 			page_move_anon_rmap(&old_folio->page, vma);
+			SetPageAnonExclusive(&old_folio->page);
+		}
 		if (likely(!unshare))
 			set_huge_ptep_writable(vma, haddr, ptep);