Merge tag 'folio-5.18c' of git://git.infradead.org/users/willy/pagecache

Pull folio updates from Matthew Wilcox:

 - Rewrite how munlock works to massively reduce the contention on
   i_mmap_rwsem (Hugh Dickins):

     https://lore.kernel.org/linux-mm/8e4356d-9622-a7f0-b2c-f116b5f2efea@google.com/

 - Sort out the page refcount mess for ZONE_DEVICE pages (Christoph
   Hellwig):

     https://lore.kernel.org/linux-mm/20220210072828.2930359-1-hch@lst.de/

 - Convert GUP to use folios and make pincount available for order-1
   pages. (Matthew Wilcox)

 - Convert a few more truncation functions to use folios (Matthew
   Wilcox)

 - Convert page_vma_mapped_walk to use PFNs instead of pages (Matthew
   Wilcox)

 - Convert rmap_walk to use folios (Matthew Wilcox)

 - Convert most of shrink_page_list() to use a folio (Matthew Wilcox)

 - Add support for creating large folios in readahead (Matthew Wilcox)

* tag 'folio-5.18c' of git://git.infradead.org/users/willy/pagecache: (114 commits)
  mm/damon: minor cleanup for damon_pa_young
  selftests/vm/transhuge-stress: Support file-backed PMD folios
  mm/filemap: Support VM_HUGEPAGE for file mappings
  mm/readahead: Switch to page_cache_ra_order
  mm/readahead: Align file mappings for non-DAX
  mm/readahead: Add large folio readahead
  mm: Support arbitrary THP sizes
  mm: Make large folios depend on THP
  mm: Fix READ_ONLY_THP warning
  mm/filemap: Allow large folios to be added to the page cache
  mm: Turn can_split_huge_page() into can_split_folio()
  mm/vmscan: Convert pageout() to take a folio
  mm/vmscan: Turn page_check_references() into folio_check_references()
  mm/vmscan: Account large folios correctly
  mm/vmscan: Optimise shrink_page_list for non-PMD-sized folios
  mm/vmscan: Free non-shmem folios without splitting them
  mm/rmap: Constify the rmap_walk_control argument
  mm/rmap: Convert rmap_walk() to take a folio
  mm: Turn page_anon_vma() into folio_anon_vma()
  mm/rmap: Turn page_lock_anon_vma_read() into folio_lock_anon_vma_read()
  ...

27 files changed, 44 insertions, 15 deletions

diff --git a/arch/alpha/include/asm/pgtable.h b/arch/alpha/include/asm/pgtable.h
index 02f0429f1068..170451fde043 100644
--- a/arch/alpha/include/asm/pgtable.h
+++ b/arch/alpha/include/asm/pgtable.h
@@ -233,6 +233,7 @@ pmd_page_vaddr(pmd_t pmd)
 	return ((pmd_val(pmd) & _PFN_MASK) >> (32-PAGE_SHIFT)) + PAGE_OFFSET;
 }
 
+#define pmd_pfn(pmd)	(pmd_val(pmd) >> 32)
 #define pmd_page(pmd)	(pfn_to_page(pmd_val(pmd) >> 32))
 #define pud_page(pud)	(pfn_to_page(pud_val(pud) >> 32))
 
diff --git a/arch/arc/include/asm/hugepage.h b/arch/arc/include/asm/hugepage.h
index 11b0ff26b97b..5001b796fb8d 100644
--- a/arch/arc/include/asm/hugepage.h
+++ b/arch/arc/include/asm/hugepage.h
@@ -31,7 +31,6 @@ static inline pmd_t pte_pmd(pte_t pte)
 
 #define pmd_write(pmd)		pte_write(pmd_pte(pmd))
 #define pmd_young(pmd)		pte_young(pmd_pte(pmd))
-#define pmd_pfn(pmd)		pte_pfn(pmd_pte(pmd))
 #define pmd_dirty(pmd)		pte_dirty(pmd_pte(pmd))
 
 #define mk_pmd(page, prot)	pte_pmd(mk_pte(page, prot))
diff --git a/arch/arc/include/asm/pgtable-levels.h b/arch/arc/include/asm/pgtable-levels.h
index 8084ef2f6491..7848348719b2 100644
--- a/arch/arc/include/asm/pgtable-levels.h
+++ b/arch/arc/include/asm/pgtable-levels.h
@@ -161,6 +161,7 @@
 #define pmd_present(x)		(pmd_val(x))
 #define pmd_clear(xp)		do { pmd_val(*(xp)) = 0; } while (0)
 #define pmd_page_vaddr(pmd)	(pmd_val(pmd) & PAGE_MASK)
+#define pmd_pfn(pmd)		((pmd_val(pmd) & PAGE_MASK) >> PAGE_SHIFT)
 #define pmd_page(pmd)		virt_to_page(pmd_page_vaddr(pmd))
 #define set_pmd(pmdp, pmd)	(*(pmdp) = pmd)
 #define pmd_pgtable(pmd)	((pgtable_t) pmd_page_vaddr(pmd))
diff --git a/arch/arm/include/asm/pgtable-2level.h b/arch/arm/include/asm/pgtable-2level.h
index 70fe69bdcce2..92abd4cd8ca2 100644
--- a/arch/arm/include/asm/pgtable-2level.h
+++ b/arch/arm/include/asm/pgtable-2level.h
@@ -208,6 +208,8 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
 }
 #define pmd_offset pmd_offset
 
+#define pmd_pfn(pmd)		(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK))
+
 #define pmd_large(pmd)		(pmd_val(pmd) & 2)
 #define pmd_leaf(pmd)		(pmd_val(pmd) & 2)
 #define pmd_bad(pmd)		(pmd_val(pmd) & 2)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 0b7d25887ec3..626ec32873c6 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -17,6 +17,7 @@
 #include <linux/mman.h>
 #include <linux/nodemask.h>
 #include <linux/memblock.h>
+#include <linux/memremap.h>
 #include <linux/memory.h>
 #include <linux/fs.h>
 #include <linux/io.h>
diff --git a/arch/csky/include/asm/pgtable.h b/arch/csky/include/asm/pgtable.h
index 151607ed5158..bbe245117777 100644
--- a/arch/csky/include/asm/pgtable.h
+++ b/arch/csky/include/asm/pgtable.h
@@ -30,6 +30,7 @@
 #define pgd_ERROR(e) \
 	pr_err("%s:%d: bad pgd %08lx.\n", __FILE__, __LINE__, pgd_val(e))
 
+#define pmd_pfn(pmd)	(pmd_phys(pmd) >> PAGE_SHIFT)
 #define pmd_page(pmd)	(pfn_to_page(pmd_phys(pmd) >> PAGE_SHIFT))
 #define pte_clear(mm, addr, ptep)	set_pte((ptep), \
 	(((unsigned int) addr >= PAGE_OFFSET) ? __pte(_PAGE_GLOBAL) : __pte(0)))
diff --git a/arch/hexagon/include/asm/pgtable.h b/arch/hexagon/include/asm/pgtable.h
index 18cd6ea9ab23..0610724d6a28 100644
--- a/arch/hexagon/include/asm/pgtable.h
+++ b/arch/hexagon/include/asm/pgtable.h
@@ -236,6 +236,11 @@ static inline int pmd_bad(pmd_t pmd)
 }
 
 /*
+ * pmd_pfn - converts a PMD entry to a page frame number
+ */
+#define pmd_pfn(pmd)  (pmd_val(pmd) >> PAGE_SHIFT)
+
+/*
  * pmd_page - converts a PMD entry to a page pointer
  */
 #define pmd_page(pmd)  (pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT))
diff --git a/arch/ia64/include/asm/pgtable.h b/arch/ia64/include/asm/pgtable.h
index 9584b2c5f394..7aa8f2330fb1 100644
--- a/arch/ia64/include/asm/pgtable.h
+++ b/arch/ia64/include/asm/pgtable.h
@@ -267,6 +267,7 @@ ia64_phys_addr_valid (unsigned long addr)
 #define pmd_present(pmd)		(pmd_val(pmd) != 0UL)
 #define pmd_clear(pmdp)			(pmd_val(*(pmdp)) = 0UL)
 #define pmd_page_vaddr(pmd)		((unsigned long) __va(pmd_val(pmd) & _PFN_MASK))
+#define pmd_pfn(pmd)			((pmd_val(pmd) & _PFN_MASK) >> PAGE_SHIFT)
 #define pmd_page(pmd)			virt_to_page((pmd_val(pmd) + PAGE_OFFSET))
 
 #define pud_none(pud)			(!pud_val(pud))
diff --git a/arch/m68k/include/asm/mcf_pgtable.h b/arch/m68k/include/asm/mcf_pgtable.h
index 6f2b87d7a50d..94f38d76e278 100644
--- a/arch/m68k/include/asm/mcf_pgtable.h
+++ b/arch/m68k/include/asm/mcf_pgtable.h
@@ -322,6 +322,7 @@ extern pgd_t kernel_pg_dir[PTRS_PER_PGD];
 #define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })
 #define __swp_entry_to_pte(x)	(__pte((x).val))
 
+#define pmd_pfn(pmd)		(pmd_val(pmd) >> PAGE_SHIFT)
 #define pmd_page(pmd)		(pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT))
 
 #define pfn_pte(pfn, prot)	__pte(((pfn) << PAGE_SHIFT) | pgprot_val(prot))
diff --git a/arch/m68k/include/asm/motorola_pgtable.h b/arch/m68k/include/asm/motorola_pgtable.h
index 022c3abc280d..7c9b56e2a750 100644
--- a/arch/m68k/include/asm/motorola_pgtable.h
+++ b/arch/m68k/include/asm/motorola_pgtable.h
@@ -147,6 +147,7 @@ static inline void pud_set(pud_t *pudp, pmd_t *pmdp)
 #define pmd_present(pmd)	(pmd_val(pmd) & _PAGE_TABLE)
 #define pmd_clear(pmdp)		({ pmd_val(*pmdp) = 0; })
 
+#define pmd_pfn(pmd)		((pmd_val(pmd) & _TABLE_MASK) >> PAGE_SHIFT)
 /*
  * m68k does not have huge pages (020/030 actually could), but generic code
  * expects pmd_page() to exists, only to then DCE it all. Provide a dummy to
diff --git a/arch/m68k/include/asm/sun3_pgtable.h b/arch/m68k/include/asm/sun3_pgtable.h
index 5b24283a0a42..5e4e753f0d24 100644
--- a/arch/m68k/include/asm/sun3_pgtable.h
+++ b/arch/m68k/include/asm/sun3_pgtable.h
@@ -130,6 +130,7 @@ static inline void pte_clear (struct mm_struct *mm, unsigned long addr, pte_t *p
 ({ pte_t __pte; pte_val(__pte) = pfn | pgprot_val(pgprot); __pte; })
 
 #define pte_page(pte)		virt_to_page(__pte_page(pte))
+#define pmd_pfn(pmd)		(pmd_val(pmd) >> PAGE_SHIFT)
 #define pmd_page(pmd)		virt_to_page(pmd_page_vaddr(pmd))
 
 
diff --git a/arch/microblaze/include/asm/pgtable.h b/arch/microblaze/include/asm/pgtable.h
index c136a01e467e..0c72646370e1 100644
--- a/arch/microblaze/include/asm/pgtable.h
+++ b/arch/microblaze/include/asm/pgtable.h
@@ -399,6 +399,9 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd)
 	return ((unsigned long) (pmd_val(pmd) & PAGE_MASK));
 }
 
+/* returns pfn of the pmd entry*/
+#define pmd_pfn(pmd)	(__pa(pmd_val(pmd)) >> PAGE_SHIFT)
+
 /* returns struct *page of the pmd entry*/
 #define pmd_page(pmd)	(pfn_to_page(__pa(pmd_val(pmd)) >> PAGE_SHIFT))
 
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 7b8037f25d9e..374c6322775d 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -86,6 +86,11 @@ extern void paging_init(void);
  */
 #define pmd_phys(pmd)		virt_to_phys((void *)pmd_val(pmd))
 
+static inline unsigned long pmd_pfn(pmd_t pmd)
+{
+	return pmd_val(pmd) >> _PFN_SHIFT;
+}
+
 #ifndef CONFIG_MIPS_HUGE_TLB_SUPPORT
 #define pmd_page(pmd)		(pfn_to_page(pmd_phys(pmd) >> PAGE_SHIFT))
 #endif /* CONFIG_MIPS_HUGE_TLB_SUPPORT */
@@ -422,11 +427,6 @@ static inline int pmd_write(pmd_t pmd)
 	return !!(pmd_val(pmd) & _PAGE_WRITE);
 }
 
-static inline unsigned long pmd_pfn(pmd_t pmd)
-{
-	return pmd_val(pmd) >> _PFN_SHIFT;
-}
-
 static inline struct page *pmd_page(pmd_t pmd)
 {
 	if (pmd_val(pmd) & _PAGE_HUGE)
diff --git a/arch/nds32/include/asm/pgtable.h b/arch/nds32/include/asm/pgtable.h
index 419f984eef70..7ff144467b29 100644
--- a/arch/nds32/include/asm/pgtable.h
+++ b/arch/nds32/include/asm/pgtable.h
@@ -308,6 +308,7 @@ static inline pmd_t __mk_pmd(pte_t * ptep, unsigned long prot)
 	return pmd;
 }
 
+#define pmd_pfn(pmd)	     (pmd_val(pmd) >> PAGE_SHIFT)
 #define pmd_page(pmd)        virt_to_page(__va(pmd_val(pmd)))
 
 /*
diff --git a/arch/nios2/include/asm/pgtable.h b/arch/nios2/include/asm/pgtable.h
index 4a995fa628ee..262d0609268c 100644
--- a/arch/nios2/include/asm/pgtable.h
+++ b/arch/nios2/include/asm/pgtable.h
@@ -235,6 +235,7 @@ static inline void pte_clear(struct mm_struct *mm,
  * and a page entry and page directory to the page they refer to.
  */
 #define pmd_phys(pmd)		virt_to_phys((void *)pmd_val(pmd))
+#define pmd_pfn(pmd)		(pmd_phys(pmd) >> PAGE_SHIFT)
 #define pmd_page(pmd)		(pfn_to_page(pmd_phys(pmd) >> PAGE_SHIFT))
 
 static inline unsigned long pmd_page_vaddr(pmd_t pmd)
diff --git a/arch/openrisc/include/asm/pgtable.h b/arch/openrisc/include/asm/pgtable.h
index cdd657f80bfa..c3abbf71e09f 100644
--- a/arch/openrisc/include/asm/pgtable.h
+++ b/arch/openrisc/include/asm/pgtable.h
@@ -361,6 +361,7 @@ static inline void pmd_set(pmd_t *pmdp, pte_t *ptep)
 	pmd_val(*pmdp) = _KERNPG_TABLE | (unsigned long) ptep;
 }
 
+#define pmd_pfn(pmd)		(pmd_val(pmd) >> PAGE_SHIFT)
 #define pmd_page(pmd)		(pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT))
 
 static inline unsigned long pmd_page_vaddr(pmd_t pmd)
diff --git a/arch/parisc/include/asm/pgtable.h b/arch/parisc/include/asm/pgtable.h
index 7dff736936d0..939db6fe620b 100644
--- a/arch/parisc/include/asm/pgtable.h
+++ b/arch/parisc/include/asm/pgtable.h
@@ -408,6 +408,7 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd)
 	return ((unsigned long) __va(pmd_address(pmd)));
 }
 
+#define pmd_pfn(pmd)	(pmd_address(pmd) >> PAGE_SHIFT)
 #define __pmd_page(pmd) ((unsigned long) __va(pmd_address(pmd)))
 #define pmd_page(pmd)	virt_to_page((void *)__pmd_page(pmd))
 
diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index f8b94f78403f..95e06f2a8e23 100644
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -372,8 +372,8 @@ static inline void __ptep_set_access_flags(struct vm_area_struct *vma,
 #define __HAVE_ARCH_PTE_SAME
 #define pte_same(A,B)	(((pte_val(A) ^ pte_val(B)) & ~_PAGE_HASHPTE) == 0)
 
-#define pmd_page(pmd)		\
-	pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)
+#define pmd_pfn(pmd)		(pmd_val(pmd) >> PAGE_SHIFT)
+#define pmd_page(pmd)		pfn_to_page(pmd_pfn(pmd))
 
 /*
  * Encode and decode a swap entry.
diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index fd277b15635c..b8527a74bd4d 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -21,7 +21,6 @@ extern void destroy_context(struct mm_struct *mm);
 #ifdef CONFIG_SPAPR_TCE_IOMMU
 struct mm_iommu_table_group_mem_t;
 
-extern int isolate_lru_page(struct page *page);	/* from internal.h */
 extern bool mm_iommu_preregistered(struct mm_struct *mm);
 extern long mm_iommu_new(struct mm_struct *mm,
 		unsigned long ua, unsigned long entries,
diff --git a/arch/powerpc/include/asm/nohash/32/pgtable.h b/arch/powerpc/include/asm/nohash/32/pgtable.h
index d959c2a73fbf..dcc9b338e042 100644
--- a/arch/powerpc/include/asm/nohash/32/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/32/pgtable.h
@@ -349,15 +349,14 @@ static inline int pte_young(pte_t pte)
  * of the pte page.  -- paulus
  */
 #ifndef CONFIG_BOOKE
-#define pmd_page(pmd)		\
-	pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)
+#define pmd_pfn(pmd)		(pmd_val(pmd) >> PAGE_SHIFT)
 #else
 #define pmd_page_vaddr(pmd)	\
 	((unsigned long)(pmd_val(pmd) & ~(PTE_TABLE_SIZE - 1)))
-#define pmd_page(pmd)		\
-	pfn_to_page((__pa(pmd_val(pmd)) >> PAGE_SHIFT))
+#define pmd_pfn(pmd)		(__pa(pmd_val(pmd)) >> PAGE_SHIFT)
 #endif
 
+#define pmd_page(pmd)		pfn_to_page(pmd_pfn(pmd))
 /*
  * Encode and decode a swap entry.
  * Note that the bits we use in a PTE for representing a swap entry
diff --git a/arch/powerpc/include/asm/nohash/64/pgtable.h b/arch/powerpc/include/asm/nohash/64/pgtable.h
index 2816d158280a..78888b0c30f6 100644
--- a/arch/powerpc/include/asm/nohash/64/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/64/pgtable.h
@@ -142,6 +142,7 @@ static inline pte_t pmd_pte(pmd_t pmd)
 #define	pmd_present(pmd)	(!pmd_none(pmd))
 #define pmd_page_vaddr(pmd)	(pmd_val(pmd) & ~PMD_MASKED_BITS)
 extern struct page *pmd_page(pmd_t pmd);
+#define pmd_pfn(pmd)		(page_to_pfn(pmd_page(pmd)))
 
 static inline void pud_set(pud_t *pudp, unsigned long val)
 {
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index e414ca44839f..8cabdb39cbbc 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -91,6 +91,7 @@
 #include <linux/kvm_host.h>
 #include <linux/ksm.h>
 #include <linux/of.h>
+#include <linux/memremap.h>
 #include <asm/ultravisor.h>
 #include <asm/mman.h>
 #include <asm/kvm_ppc.h>
@@ -712,7 +713,6 @@ static struct page *kvmppc_uvmem_get_page(unsigned long gpa, struct kvm *kvm)
 
 	dpage = pfn_to_page(uvmem_pfn);
 	dpage->zone_device_data = pvt;
-	get_page(dpage);
 	lock_page(dpage);
 	return dpage;
 out_clear:
diff --git a/arch/powerpc/mm/book3s64/pgtable.c b/arch/powerpc/mm/book3s64/pgtable.c
index 79ce3c22a29d..052e6590f84f 100644
--- a/arch/powerpc/mm/book3s64/pgtable.c
+++ b/arch/powerpc/mm/book3s64/pgtable.c
@@ -6,6 +6,7 @@
 #include <linux/sched.h>
 #include <linux/mm_types.h>
 #include <linux/memblock.h>
+#include <linux/memremap.h>
 #include <linux/debugfs.h>
 #include <misc/cxl-base.h>
 
diff --git a/arch/sh/include/asm/pgtable_32.h b/arch/sh/include/asm/pgtable_32.h
index 41be43e99cff..d0240decacca 100644
--- a/arch/sh/include/asm/pgtable_32.h
+++ b/arch/sh/include/asm/pgtable_32.h
@@ -406,6 +406,7 @@ static inline unsigned long pmd_page_vaddr(pmd_t pmd)
 	return (unsigned long)pmd_val(pmd);
 }
 
+#define pmd_pfn(pmd)		(__pa(pmd_val(pmd)) >> PAGE_SHIFT)
 #define pmd_page(pmd)		(virt_to_page(pmd_val(pmd)))
 
 #ifdef CONFIG_X2TLB
diff --git a/arch/sparc/include/asm/pgtable_32.h b/arch/sparc/include/asm/pgtable_32.h
index ffccfe3b22ed..4866625da314 100644
--- a/arch/sparc/include/asm/pgtable_32.h
+++ b/arch/sparc/include/asm/pgtable_32.h
@@ -127,11 +127,16 @@ static inline int srmmu_device_memory(unsigned long x)
 	return ((x & 0xF0000000) != 0);
 }
 
+static inline unsigned long pmd_pfn(pmd_t pmd)
+{
+	return (pmd_val(pmd) & SRMMU_PTD_PMASK) >> (PAGE_SHIFT-4);
+}
+
 static inline struct page *pmd_page(pmd_t pmd)
 {
 	if (srmmu_device_memory(pmd_val(pmd)))
 		BUG();
-	return pfn_to_page((pmd_val(pmd) & SRMMU_PTD_PMASK) >> (PAGE_SHIFT-4));
+	return pfn_to_page(pmd_pfn(pmd));
 }
 
 static inline unsigned long __pmd_page(pmd_t pmd)
diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable.h
index b9e20bbe2f75..167e236d9bb8 100644
--- a/arch/um/include/asm/pgtable.h
+++ b/arch/um/include/asm/pgtable.h
@@ -109,6 +109,7 @@ extern unsigned long end_iomem;
 #define p4d_newpage(x)  (p4d_val(x) & _PAGE_NEWPAGE)
 #define p4d_mkuptodate(x) (p4d_val(x) &= ~_PAGE_NEWPAGE)
 
+#define pmd_pfn(pmd) (pmd_val(pmd) >> PAGE_SHIFT)
 #define pmd_page(pmd) phys_to_page(pmd_val(pmd) & PAGE_MASK)
 
 #define pte_page(x) pfn_to_page(pte_pfn(x))
diff --git a/arch/xtensa/include/asm/pgtable.h b/arch/xtensa/include/asm/pgtable.h
index bd5aeb795567..8da562f5da73 100644
--- a/arch/xtensa/include/asm/pgtable.h
+++ b/arch/xtensa/include/asm/pgtable.h
@@ -241,6 +241,7 @@ static inline void paging_init(void) { }
  * The pmd contains the kernel virtual address of the pte page.
  */
 #define pmd_page_vaddr(pmd) ((unsigned long)(pmd_val(pmd) & PAGE_MASK))
+#define pmd_pfn(pmd) (__pa(pmd_val(pmd)) >> PAGE_SHIFT)
 #define pmd_page(pmd) virt_to_page(pmd_val(pmd))
 
 /*