[PATCH 3/4] mm: Add folio_mk_pmd()

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

Removes five conversions from folio to page.  Also removes both callers
of mk_pmd() that aren't part of mk_huge_pmd(), getting us a step closer to
removing the confusion between mk_pmd(), mk_huge_pmd() and pmd_mkhuge().

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/dax.c           |  3 +--
 include/linux/mm.h | 17 +++++++++++++++++
 mm/huge_memory.c   | 11 +++++------
 mm/khugepaged.c    |  2 +-
 mm/memory.c        |  2 +-
 5 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 21b47402b3dc..22efc6c44539 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1237,8 +1237,7 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf,
 		pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, pgtable);
 		mm_inc_nr_ptes(vma->vm_mm);
 	}
-	pmd_entry = mk_pmd(&zero_folio->page, vmf->vma->vm_page_prot);
-	pmd_entry = pmd_mkhuge(pmd_entry);
+	pmd_entry = folio_mk_pmd(zero_folio, vmf->vma->vm_page_prot);
 	set_pmd_at(vmf->vma->vm_mm, pmd_addr, vmf->pmd, pmd_entry);
 	spin_unlock(ptl);
 	trace_dax_pmd_load_hole(inode, vmf, zero_folio, *entry);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index b1e311bae6b7..5c883c619fa4 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1936,7 +1936,24 @@ static inline pte_t folio_mk_pte(struct folio *folio, pgprot_t pgprot)
 {
 	return pfn_pte(folio_pfn(folio), pgprot);
 }
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+/**
+ * folio_mk_pmd - Create a PMD for this folio
+ * @folio: The folio to create a PMD for
+ * @pgprot: The page protection bits to use
+ *
+ * Create a page table entry for the first page of this folio.
+ * This is suitable for passing to set_pmd_at().
+ *
+ * Return: A page table entry suitable for mapping this folio.
+ */
+static inline pmd_t folio_mk_pmd(struct folio *folio, pgprot_t pgprot)
+{
+	return pmd_mkhuge(pfn_pmd(folio_pfn(folio), pgprot));
+}
 #endif
+#endif /* CONFIG_MMU */
 
 /**
  * folio_maybe_dma_pinned - Report if a folio may be pinned for DMA.
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 3d3ebdc002d5..95ed5dd9622b 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1203,7 +1203,7 @@ static void map_anon_folio_pmd(struct folio *folio, pmd_t *pmd,
 {
 	pmd_t entry;
 
-	entry = mk_huge_pmd(&folio->page, vma->vm_page_prot);
+	entry = folio_mk_pmd(folio, vma->vm_page_prot);
 	entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
 	folio_add_new_anon_rmap(folio, vma, haddr, RMAP_EXCLUSIVE);
 	folio_add_lru_vma(folio, vma);
@@ -1311,8 +1311,7 @@ static void set_huge_zero_folio(pgtable_t pgtable, struct mm_struct *mm,
 	pmd_t entry;
 	if (!pmd_none(*pmd))
 		return;
-	entry = mk_pmd(&zero_folio->page, vma->vm_page_prot);
-	entry = pmd_mkhuge(entry);
+	entry = folio_mk_pmd(zero_folio, vma->vm_page_prot);
 	pgtable_trans_huge_deposit(mm, pmd, pgtable);
 	set_pmd_at(mm, haddr, pmd, entry);
 	mm_inc_nr_ptes(mm);
@@ -2570,12 +2569,12 @@ int move_pages_huge_pmd(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd, pm
 		folio_move_anon_rmap(src_folio, dst_vma);
 		src_folio->index = linear_page_index(dst_vma, dst_addr);
 
-		_dst_pmd = mk_huge_pmd(&src_folio->page, dst_vma->vm_page_prot);
+		_dst_pmd = folio_mk_pmd(src_folio, dst_vma->vm_page_prot);
 		/* Follow mremap() behavior and treat the entry dirty after the move */
 		_dst_pmd = pmd_mkwrite(pmd_mkdirty(_dst_pmd), dst_vma);
 	} else {
 		src_pmdval = pmdp_huge_clear_flush(src_vma, src_addr, src_pmd);
-		_dst_pmd = mk_huge_pmd(src_page, dst_vma->vm_page_prot);
+		_dst_pmd = folio_mk_pmd(src_folio, dst_vma->vm_page_prot);
 	}
 	set_pmd_at(mm, dst_addr, dst_pmd, _dst_pmd);
 
@@ -4306,7 +4305,7 @@ void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
 
 	entry = pmd_to_swp_entry(*pvmw->pmd);
 	folio_get(folio);
-	pmde = mk_huge_pmd(new, READ_ONCE(vma->vm_page_prot));
+	pmde = folio_mk_pmd(folio, READ_ONCE(vma->vm_page_prot));
 	if (pmd_swp_soft_dirty(*pvmw->pmd))
 		pmde = pmd_mksoft_dirty(pmde);
 	if (is_writable_migration_entry(entry))
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 5f0be134141e..4f85597a7f64 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1239,7 +1239,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address,
 	__folio_mark_uptodate(folio);
 	pgtable = pmd_pgtable(_pmd);
 
-	_pmd = mk_huge_pmd(&folio->page, vma->vm_page_prot);
+	_pmd = folio_mk_pmd(folio, vma->vm_page_prot);
 	_pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
 
 	spin_lock(pmd_ptl);
diff --git a/mm/memory.c b/mm/memory.c
index ea5a58db76dd..6d1a1185c34c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5078,7 +5078,7 @@ vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
 
 	flush_icache_pages(vma, page, HPAGE_PMD_NR);
 
-	entry = mk_huge_pmd(page, vma->vm_page_prot);
+	entry = folio_mk_pmd(folio, vma->vm_page_prot);
 	if (write)
 		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
 
-- 
2.47.2