Balbir Singh
2025-Mar-06 04:42 UTC
[RFC 01/11] mm/zone_device: support large zone device private folios
Add routines to support allocation of large order zone device folios
and helper functions for zone device folios, to check if a folio is
device private and helpers for setting zone device data.
When large folios are used, the existing page_free() callback in
pgmap is called when the folio is freed, this is true for both
PAGE_SIZE and higher order pages.
Signed-off-by: Balbir Singh <balbirs at nvidia.com>
---
include/linux/memremap.h | 22 +++++++++++++++++-
mm/memremap.c | 50 +++++++++++++++++++++++++++++-----------
2 files changed, 58 insertions(+), 14 deletions(-)
diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 4aa151914eab..11d586dd8ef1 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -169,6 +169,18 @@ static inline bool folio_is_device_private(const struct
folio *folio)
return is_device_private_page(&folio->page);
}
+static inline void *folio_zone_device_data(const struct folio *folio)
+{
+ VM_BUG_ON_FOLIO(!folio_is_device_private(folio), folio);
+ return folio->page.zone_device_data;
+}
+
+static inline void folio_set_zone_device_data(struct folio *folio, void *data)
+{
+ VM_BUG_ON_FOLIO(!folio_is_device_private(folio), folio);
+ folio->page.zone_device_data = data;
+}
+
static inline bool is_pci_p2pdma_page(const struct page *page)
{
return IS_ENABLED(CONFIG_PCI_P2PDMA) &&
@@ -199,7 +211,7 @@ static inline bool folio_is_fsdax(const struct folio *folio)
}
#ifdef CONFIG_ZONE_DEVICE
-void zone_device_page_init(struct page *page);
+void init_zone_device_folio(struct folio *folio, unsigned int order);
void *memremap_pages(struct dev_pagemap *pgmap, int nid);
void memunmap_pages(struct dev_pagemap *pgmap);
void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
@@ -209,6 +221,14 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn);
unsigned long memremap_compat_align(void);
+
+static inline void zone_device_page_init(struct page *page)
+{
+ struct folio *folio = page_folio(page);
+
+ init_zone_device_folio(folio, 0);
+}
+
#else
static inline void *devm_memremap_pages(struct device *dev,
struct dev_pagemap *pgmap)
diff --git a/mm/memremap.c b/mm/memremap.c
index 2aebc1b192da..7d98d0a4c0cd 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -459,20 +459,21 @@ EXPORT_SYMBOL_GPL(get_dev_pagemap);
void free_zone_device_folio(struct folio *folio)
{
struct dev_pagemap *pgmap = folio->pgmap;
+ unsigned int nr = folio_nr_pages(folio);
+ int i;
+ bool anon = folio_test_anon(folio);
+ struct page *page = folio_page(folio, 0);
if (WARN_ON_ONCE(!pgmap))
return;
mem_cgroup_uncharge(folio);
- /*
- * Note: we don't expect anonymous compound pages yet. Once supported
- * and we could PTE-map them similar to THP, we'd have to clear
- * PG_anon_exclusive on all tail pages.
- */
- if (folio_test_anon(folio)) {
- VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
- __ClearPageAnonExclusive(folio_page(folio, 0));
+ WARN_ON_ONCE(folio_test_large(folio) && !anon);
+
+ for (i = 0; i < nr; i++) {
+ if (anon)
+ __ClearPageAnonExclusive(folio_page(folio, i));
}
/*
@@ -496,10 +497,19 @@ void free_zone_device_folio(struct folio *folio)
switch (pgmap->type) {
case MEMORY_DEVICE_PRIVATE:
+ if (folio_test_large(folio)) {
+ folio_unqueue_deferred_split(folio);
+
+ percpu_ref_put_many(&folio->pgmap->ref, nr - 1);
+ }
+ pgmap->ops->page_free(page);
+ put_dev_pagemap(pgmap);
+ page->mapping = NULL;
+ break;
case MEMORY_DEVICE_COHERENT:
if (WARN_ON_ONCE(!pgmap->ops || !pgmap->ops->page_free))
break;
- pgmap->ops->page_free(folio_page(folio, 0));
+ pgmap->ops->page_free(page);
put_dev_pagemap(pgmap);
break;
@@ -523,14 +533,28 @@ void free_zone_device_folio(struct folio *folio)
}
}
-void zone_device_page_init(struct page *page)
+void init_zone_device_folio(struct folio *folio, unsigned int order)
{
+ struct page *page = folio_page(folio, 0);
+
+ VM_BUG_ON(order > MAX_ORDER_NR_PAGES);
+
+ WARN_ON_ONCE(order && order != HPAGE_PMD_ORDER);
+
/*
* Drivers shouldn't be allocating pages after calling
* memunmap_pages().
*/
- WARN_ON_ONCE(!percpu_ref_tryget_live(&page_pgmap(page)->ref));
- set_page_count(page, 1);
+ WARN_ON_ONCE(!percpu_ref_tryget_many(&page_pgmap(page)->ref, 1 <<
order));
+ folio_set_count(folio, 1);
lock_page(page);
+
+ /*
+ * Only PMD level migration is supported for THP migration
+ */
+ if (order > 1) {
+ prep_compound_page(page, order);
+ folio_set_large_rmappable(folio);
+ }
}
-EXPORT_SYMBOL_GPL(zone_device_page_init);
+EXPORT_SYMBOL_GPL(init_zone_device_folio);
--
2.48.1
Alistair Popple
2025-Mar-06 23:02 UTC
[RFC 01/11] mm/zone_device: support large zone device private folios
On Thu, Mar 06, 2025 at 03:42:29PM +1100, Balbir Singh wrote:> Add routines to support allocation of large order zone device folios > and helper functions for zone device folios, to check if a folio is > device private and helpers for setting zone device data. > > When large folios are used, the existing page_free() callback in > pgmap is called when the folio is freed, this is true for both > PAGE_SIZE and higher order pages. > > Signed-off-by: Balbir Singh <balbirs at nvidia.com> > --- > include/linux/memremap.h | 22 +++++++++++++++++- > mm/memremap.c | 50 +++++++++++++++++++++++++++++----------- > 2 files changed, 58 insertions(+), 14 deletions(-) > > diff --git a/include/linux/memremap.h b/include/linux/memremap.h > index 4aa151914eab..11d586dd8ef1 100644 > --- a/include/linux/memremap.h > +++ b/include/linux/memremap.h > @@ -169,6 +169,18 @@ static inline bool folio_is_device_private(const struct folio *folio) > return is_device_private_page(&folio->page); > } > > +static inline void *folio_zone_device_data(const struct folio *folio) > +{ > + VM_BUG_ON_FOLIO(!folio_is_device_private(folio), folio); > + return folio->page.zone_device_data; > +} > + > +static inline void folio_set_zone_device_data(struct folio *folio, void *data) > +{ > + VM_BUG_ON_FOLIO(!folio_is_device_private(folio), folio); > + folio->page.zone_device_data = data; > +} > + > static inline bool is_pci_p2pdma_page(const struct page *page) > { > return IS_ENABLED(CONFIG_PCI_P2PDMA) && > @@ -199,7 +211,7 @@ static inline bool folio_is_fsdax(const struct folio *folio) > } > > #ifdef CONFIG_ZONE_DEVICE > -void zone_device_page_init(struct page *page); > +void init_zone_device_folio(struct folio *folio, unsigned int order); > void *memremap_pages(struct dev_pagemap *pgmap, int nid); > void memunmap_pages(struct dev_pagemap *pgmap); > void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap); > @@ -209,6 +221,14 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn, > bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn); > > unsigned long memremap_compat_align(void); > + > +static inline void zone_device_page_init(struct page *page) > +{ > + struct folio *folio = page_folio(page); > + > + init_zone_device_folio(folio, 0); > +} > + > #else > static inline void *devm_memremap_pages(struct device *dev, > struct dev_pagemap *pgmap) > diff --git a/mm/memremap.c b/mm/memremap.c > index 2aebc1b192da..7d98d0a4c0cd 100644 > --- a/mm/memremap.c > +++ b/mm/memremap.c > @@ -459,20 +459,21 @@ EXPORT_SYMBOL_GPL(get_dev_pagemap); > void free_zone_device_folio(struct folio *folio) > { > struct dev_pagemap *pgmap = folio->pgmap; > + unsigned int nr = folio_nr_pages(folio); > + int i; > + bool anon = folio_test_anon(folio); > + struct page *page = folio_page(folio, 0); > > if (WARN_ON_ONCE(!pgmap)) > return; > > mem_cgroup_uncharge(folio); > > - /* > - * Note: we don't expect anonymous compound pages yet. Once supported > - * and we could PTE-map them similar to THP, we'd have to clear > - * PG_anon_exclusive on all tail pages. > - */ > - if (folio_test_anon(folio)) { > - VM_BUG_ON_FOLIO(folio_test_large(folio), folio); > - __ClearPageAnonExclusive(folio_page(folio, 0)); > + WARN_ON_ONCE(folio_test_large(folio) && !anon); > + > + for (i = 0; i < nr; i++) { > + if (anon) > + __ClearPageAnonExclusive(folio_page(folio, i)); > } > > /* > @@ -496,10 +497,19 @@ void free_zone_device_folio(struct folio *folio) > > switch (pgmap->type) { > case MEMORY_DEVICE_PRIVATE: > + if (folio_test_large(folio)) { > + folio_unqueue_deferred_split(folio); > + > + percpu_ref_put_many(&folio->pgmap->ref, nr - 1); > + } > + pgmap->ops->page_free(page);It seems to me this would be a good time to finally convert page_free() to folio_free() and have it take a folio instead.> + put_dev_pagemap(pgmap); > + page->mapping = NULL; > + break; > case MEMORY_DEVICE_COHERENT: > if (WARN_ON_ONCE(!pgmap->ops || !pgmap->ops->page_free)) > break; > - pgmap->ops->page_free(folio_page(folio, 0)); > + pgmap->ops->page_free(page);Ditto.> put_dev_pagemap(pgmap); > break; > > @@ -523,14 +533,28 @@ void free_zone_device_folio(struct folio *folio) > } > } > > -void zone_device_page_init(struct page *page) > +void init_zone_device_folio(struct folio *folio, unsigned int order)Is this supposed to deal with taking any arbitrary zone_device folio and initialising it to the given order? If so I'd expect to see things like clear_compound_head() to cope with initialising a previously higher order folio to a 0-order folio.> { > + struct page *page = folio_page(folio, 0); > + > + VM_BUG_ON(order > MAX_ORDER_NR_PAGES); > + > + WARN_ON_ONCE(order && order != HPAGE_PMD_ORDER); > + > /* > * Drivers shouldn't be allocating pages after calling > * memunmap_pages(). > */ > - WARN_ON_ONCE(!percpu_ref_tryget_live(&page_pgmap(page)->ref)); > - set_page_count(page, 1); > + WARN_ON_ONCE(!percpu_ref_tryget_many(&page_pgmap(page)->ref, 1 << order)); > + folio_set_count(folio, 1); > lock_page(page); > + > + /* > + * Only PMD level migration is supported for THP migration > + */ > + if (order > 1) { > + prep_compound_page(page, order); > + folio_set_large_rmappable(folio); > + } > } > -EXPORT_SYMBOL_GPL(zone_device_page_init); > +EXPORT_SYMBOL_GPL(init_zone_device_folio); > -- > 2.48.1 >
David Hildenbrand
2025-Jul-08 13:37 UTC
[RFC 01/11] mm/zone_device: support large zone device private folios
On 06.03.25 05:42, Balbir Singh wrote:> Add routines to support allocation of large order zone device folios > and helper functions for zone device folios, to check if a folio is > device private and helpers for setting zone device data. > > When large folios are used, the existing page_free() callback in > pgmap is called when the folio is freed, this is true for both > PAGE_SIZE and higher order pages. > > Signed-off-by: Balbir Singh <balbirs at nvidia.com> > --- > include/linux/memremap.h | 22 +++++++++++++++++- > mm/memremap.c | 50 +++++++++++++++++++++++++++++----------- > 2 files changed, 58 insertions(+), 14 deletions(-) > > diff --git a/include/linux/memremap.h b/include/linux/memremap.h > index 4aa151914eab..11d586dd8ef1 100644 > --- a/include/linux/memremap.h > +++ b/include/linux/memremap.h > @@ -169,6 +169,18 @@ static inline bool folio_is_device_private(const struct folio *folio) > return is_device_private_page(&folio->page); > } > > +static inline void *folio_zone_device_data(const struct folio *folio) > +{ > + VM_BUG_ON_FOLIO(!folio_is_device_private(folio), folio); > + return folio->page.zone_device_data; > +}Not used.> + > +static inline void folio_set_zone_device_data(struct folio *folio, void *data) > +{ > + VM_BUG_ON_FOLIO(!folio_is_device_private(folio), folio); > + folio->page.zone_device_data = data; > +} > +Not used. Move both into the patch where they are actually used.> static inline bool is_pci_p2pdma_page(const struct page *page) > { > return IS_ENABLED(CONFIG_PCI_P2PDMA) && > @@ -199,7 +211,7 @@ static inline bool folio_is_fsdax(const struct folio *folio) > } > > #ifdef CONFIG_ZONE_DEVICE > -void zone_device_page_init(struct page *page); > +void init_zone_device_folio(struct folio *folio, unsigned int order); > void *memremap_pages(struct dev_pagemap *pgmap, int nid); > void memunmap_pages(struct dev_pagemap *pgmap); > void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap); > @@ -209,6 +221,14 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn, > bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn); > > unsigned long memremap_compat_align(void); > + > +static inline void zone_device_page_init(struct page *page) > +{ > + struct folio *folio = page_folio(page); > + > + init_zone_device_folio(folio, 0); > +} > + > #else > static inline void *devm_memremap_pages(struct device *dev, > struct dev_pagemap *pgmap) > diff --git a/mm/memremap.c b/mm/memremap.c > index 2aebc1b192da..7d98d0a4c0cd 100644 > --- a/mm/memremap.c > +++ b/mm/memremap.c > @@ -459,20 +459,21 @@ EXPORT_SYMBOL_GPL(get_dev_pagemap); > void free_zone_device_folio(struct folio *folio) > { > struct dev_pagemap *pgmap = folio->pgmap; > + unsigned int nr = folio_nr_pages(folio); > + int i; > + bool anon = folio_test_anon(folio);You can easily get rid of this (see below).> + struct page *page = folio_page(folio, 0);Please inline folio_page(folio, 0) below instead.> > if (WARN_ON_ONCE(!pgmap)) > return; > > mem_cgroup_uncharge(folio); > > - /* > - * Note: we don't expect anonymous compound pages yet. Once supported > - * and we could PTE-map them similar to THP, we'd have to clear > - * PG_anon_exclusive on all tail pages. > - */ > - if (folio_test_anon(folio)) { > - VM_BUG_ON_FOLIO(folio_test_large(folio), folio); > - __ClearPageAnonExclusive(folio_page(folio, 0)); > + WARN_ON_ONCE(folio_test_large(folio) && !anon); > + > + for (i = 0; i < nr; i++) { > + if (anon) > + __ClearPageAnonExclusive(folio_page(folio, i)); > }if (folio_test_anon(folio)) { for (i = 0; i < nr; i++) __ClearPageAnonExclusive(folio_page(folio, i)); } else { VM_WARN_ON_ONCE(folio_test_large(folio)); }> > /* > @@ -496,10 +497,19 @@ void free_zone_device_folio(struct folio *folio) > > switch (pgmap->type) { > case MEMORY_DEVICE_PRIVATE: > + if (folio_test_large(folio)) { > + folio_unqueue_deferred_split(folio);Is deferred splitting even a thing for device-private? Should we ever queue them for deferred splitting?> + > + percpu_ref_put_many(&folio->pgmap->ref, nr - 1);Looks like we instead want a helper put_dev_pagemap_refs(pgmap, nr) below instead> + } > + pgmap->ops->page_free(page); > + put_dev_pagemap(pgmap); > + page->mapping = NULL; > + break; > case MEMORY_DEVICE_COHERENT: > if (WARN_ON_ONCE(!pgmap->ops || !pgmap->ops->page_free)) > break; > - pgmap->ops->page_free(folio_page(folio, 0)); > + pgmap->ops->page_free(page); > put_dev_pagemap(pgmap); > break; > > @@ -523,14 +533,28 @@ void free_zone_device_folio(struct folio *folio) > } > } > > -void zone_device_page_init(struct page *page) > +void init_zone_device_folio(struct folio *folio, unsigned int order) > { > + struct page *page = folio_page(folio, 0); > + > + VM_BUG_ON(order > MAX_ORDER_NR_PAGES);VM_WARN_ON_ONCE() or anything else that is not *BUG, please.> + > + WARN_ON_ONCE(order && order != HPAGE_PMD_ORDER);Why do we need that limitation?> + > /* > * Drivers shouldn't be allocating pages after calling > * memunmap_pages(). > */ > - WARN_ON_ONCE(!percpu_ref_tryget_live(&page_pgmap(page)->ref)); > - set_page_count(page, 1); > + WARN_ON_ONCE(!percpu_ref_tryget_many(&page_pgmap(page)->ref, 1 << order)); > + folio_set_count(folio, 1); > lock_page(page); > + > + /* > + * Only PMD level migration is supported for THP migration > + */I don't understand how that comment interacts with the code below. This is basic large folio initialization. Drop the comment, or move it above the HPAGE_PMD_ORDER check with a clear reason why that limitation excists.> + if (order > 1) { > + prep_compound_page(page, order); > + folio_set_large_rmappable(folio); > + } > } > -EXPORT_SYMBOL_GPL(zone_device_page_init); > +EXPORT_SYMBOL_GPL(init_zone_device_folio);-- Cheers, David / dhildenb