| Message ID | 20250117163001.2326672-2-tabba@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | KVM: Restricted mapping of guest_memfd at the host and arm64 support | expand |
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@redhat.com> > Signed-off-by: Fuad Tabba <tabba@google.com> > --- > 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. You'll probably want to do the same for the PGTY_guestmem in the later patch! > + case PGTY_offline: > + /* Nothing to do, it's offline. */ > + return; > + default: > + WARN_ON_ONCE(1); > + } > +} > + > void __folio_put(struct folio *folio) > { > if (unlikely(folio_is_zone_device(folio))) { > @@ -101,8 +115,8 @@ void __folio_put(struct folio *folio) > return; > } > > - if (folio_test_hugetlb(folio)) { > - free_huge_folio(folio); > + if (unlikely(folio_has_type(folio))) { > + free_typed_folio(folio); > return; > } > > @@ -934,13 +948,13 @@ void folios_put_refs(struct folio_batch *folios, unsigned int *refs) > if (!folio_ref_sub_and_test(folio, nr_refs)) > continue; > > - /* hugetlb has its own memcg */ > - if (folio_test_hugetlb(folio)) { > + if (unlikely(folio_has_type(folio))) { > + /* typed folios have their own memcg, if any */ > if (lruvec) { > unlock_page_lruvec_irqrestore(lruvec, flags); > lruvec = NULL; > } > - free_huge_folio(folio); > + free_typed_folio(folio); > continue; > } > folio_unqueue_deferred_split(folio); > -- > 2.48.0.rc2.279.g1de40edade-goog >
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)) { + case PGTY_hugetlb: + free_huge_folio(folio); + return; + case PGTY_offline: + /* Nothing to do, it's offline. */ + return; + default: + WARN_ON_ONCE(1); + } +} + void __folio_put(struct folio *folio) { if (unlikely(folio_is_zone_device(folio))) { @@ -101,8 +115,8 @@ void __folio_put(struct folio *folio) return; } - if (folio_test_hugetlb(folio)) { - free_huge_folio(folio); + if (unlikely(folio_has_type(folio))) { + free_typed_folio(folio); return; } @@ -934,13 +948,13 @@ void folios_put_refs(struct folio_batch *folios, unsigned int *refs) if (!folio_ref_sub_and_test(folio, nr_refs)) continue; - /* hugetlb has its own memcg */ - if (folio_test_hugetlb(folio)) { + if (unlikely(folio_has_type(folio))) { + /* typed folios have their own memcg, if any */ if (lruvec) { unlock_page_lruvec_irqrestore(lruvec, flags); lruvec = NULL; } - free_huge_folio(folio); + free_typed_folio(folio); continue; } folio_unqueue_deferred_split(folio);
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@redhat.com> Signed-off-by: Fuad Tabba <tabba@google.com> --- include/linux/page-flags.h | 15 +++++++++++++++ mm/swap.c | 24 +++++++++++++++++++----- 2 files changed, 34 insertions(+), 5 deletions(-)