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 <[email protected]>
---
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
