On 17.01.25 23:05, Elliot Berman wrote:
On Fri, Jan 17, 2025 at 04:29:47PM +0000, Fuad Tabba wrote:
Some folio types, such as hugetlb, handle freeing their own
folios. Moreover, guest_memfd will require being notified once a
folio's reference count reaches 0 to facilitate shared to private
folio conversion, without the folio actually being freed at that
point.
As a first step towards that, this patch consolidates freeing
folios that have a type. The first user is hugetlb folios. Later
in this patch series, guest_memfd will become the second user of
this.
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Fuad Tabba <tabba@xxxxxxxxxx>
---
include/linux/page-flags.h | 15 +++++++++++++++
mm/swap.c | 24 +++++++++++++++++++-----
2 files changed, 34 insertions(+), 5 deletions(-)
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 691506bdf2c5..6615f2f59144 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -962,6 +962,21 @@ static inline bool page_has_type(const struct page *page)
return page_mapcount_is_type(data_race(page->page_type));
}
+static inline int page_get_type(const struct page *page)
+{
+ return page->page_type >> 24;
+}
+
+static inline bool folio_has_type(const struct folio *folio)
+{
+ return page_has_type(&folio->page);
+}
+
+static inline int folio_get_type(const struct folio *folio)
+{
+ return page_get_type(&folio->page);
+}
+
#define FOLIO_TYPE_OPS(lname, fname) \
static __always_inline bool folio_test_##fname(const struct folio *folio) \
{ \
diff --git a/mm/swap.c b/mm/swap.c
index 10decd9dffa1..6f01b56bce13 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -94,6 +94,20 @@ static void page_cache_release(struct folio *folio)
unlock_page_lruvec_irqrestore(lruvec, flags);
}
+static void free_typed_folio(struct folio *folio)
+{
+ switch (folio_get_type(folio)) {
I think you need:
+#if IS_ENABLED(CONFIG_HUGETLBFS)
+ case PGTY_hugetlb:
+ free_huge_folio(folio);
+ return;
+#endif
I think this worked before because folio_test_hugetlb was defined by:
FOLIO_TEST_FLAG_FALSE(hugetlb)
and evidently compiler optimizes out the free_huge_folio(folio) before
linking.
Likely, we should be using
case PGTY_hugetlb:
if(IF_ENABLED(CONFIG_HUGETLBFS))
free_huge_folio(folio);
return:
if possible (I assume so).
--
Cheers,
David / dhildenb
