[PATCH v4 03/36] mm: Allow hpages to be arbitrary order

Matthew Wilcox
2020-05-15T13:17:03Z

Remove the assumption in hpage_nr_pages() that compound pages are
necessarily PMD sized. Move the relevant parts of mm.h to before the
include of huge_mm.h so we can use an inline function rather than a macro.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
include/linux/huge_mm.h | 5 +--
include/linux/mm.h | 96 ++++++++++++++++++++---------------------
2 files changed, 50 insertions(+), 51 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index cfbb0a87c5f0..6bec4b5b61e1 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -265,11 +265,10 @@ static inline spinlock_t *pud_trans_huge_lock(pud_t *pud,
else
return NULL;
}
+
static inline int hpage_nr_pages(struct page *page)
{
- if (unlikely(PageTransHuge(page)))
- return HPAGE_PMD_NR;
- return 1;
+ return compound_nr(page);
}

struct page *follow_devmap_pmd(struct vm_area_struct *vma, unsigned long addr,
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 581e56275bc4..088acbda722d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -671,6 +671,54 @@ int vma_is_stack_for_current(struct vm_area_struct *vma);
struct mmu_gather;
struct inode;

+static inline unsigned int compound_order(struct page *page)
+{
+ if (!PageHead(page))
+ return 0;
+ return page[1].compound_order;
+}
+
+static inline bool hpage_pincount_available(struct page *page)
+{
+ /*
+ * Can the page->hpage_pinned_refcount field be used? That field is in
+ * the 3rd page of the compound page, so the smallest (2-page) compound
+ * pages cannot support it.
+ */
+ page = compound_head(page);
+ return PageCompound(page) && compound_order(page) > 1;
+}
+
+static inline int compound_pincount(struct page *page)
+{
+ VM_BUG_ON_PAGE(!hpage_pincount_available(page), page);
+ page = compound_head(page);
+ return atomic_read(compound_pincount_ptr(page));
+}
+
+static inline void set_compound_order(struct page *page, unsigned int order)
+{
+ page[1].compound_order = order;
+}
+
+/* Returns the number of pages in this potentially compound page. */
+static inline unsigned long compound_nr(struct page *page)
+{
+ return 1UL << compound_order(page);
+}
+
+/* Returns the number of bytes in this potentially compound page. */
+static inline unsigned long page_size(struct page *page)
+{
+ return PAGE_SIZE << compound_order(page);
+}
+
+/* Returns the number of bits needed for the number of bytes in a page */
+static inline unsigned int page_shift(struct page *page)
+{
+ return PAGE_SHIFT + compound_order(page);
+}
+
/*
* FIXME: take this include out, include page-flags.h in
* files which need it (119 of them)
@@ -875,54 +923,6 @@ static inline compound_page_dtor *get_compound_page_dtor(struct page *page)
return compound_page_dtors[page[1].compound_dtor];
}

-static inline unsigned int compound_order(struct page *page)
-{
- if (!PageHead(page))
- return 0;
- return page[1].compound_order;
-}
-
-static inline bool hpage_pincount_available(struct page *page)
-{
- /*
- * Can the page->hpage_pinned_refcount field be used? That field is in
- * the 3rd page of the compound page, so the smallest (2-page) compound
- * pages cannot support it.
- */
- page = compound_head(page);
- return PageCompound(page) && compound_order(page) > 1;
-}
-
-static inline int compound_pincount(struct page *page)
-{
- VM_BUG_ON_PAGE(!hpage_pincount_available(page), page);
- page = compound_head(page);
- return atomic_read(compound_pincount_ptr(page));
-}
-
-static inline void set_compound_order(struct page *page, unsigned int order)
-{
- page[1].compound_order = order;
-}
-
-/* Returns the number of pages in this potentially compound page. */
-static inline unsigned long compound_nr(struct page *page)
-{
- return 1UL << compound_order(page);
-}
-
-/* Returns the number of bytes in this potentially compound page. */
-static inline unsigned long page_size(struct page *page)
-{
- return PAGE_SIZE << compound_order(page);
-}
-
-/* Returns the number of bits needed for the number of bytes in a page */
-static inline unsigned int page_shift(struct page *page)
-{
- return PAGE_SHIFT + compound_order(page);
-}
-
void free_compound_page(struct page *page);

#ifdef CONFIG_MMU
--
2.26.2