Nouveau - Mar 2021 - [PATCH v3 1/8] mm: Remove special swap entry functions

Remove the migration and device private entry_to_page() and
entry_to_pfn() inline functions and instead open code them directly.
This results in shorter code which is easier to understand.

Signed-off-by: Alistair Popple <apopple at nvidia.com>
---
 arch/s390/mm/pgtable.c  |  2 +-
 fs/proc/task_mmu.c      | 23 +++++++------------
 include/linux/swap.h    |  4 ++--
 include/linux/swapops.h | 51 ++++-------------------------------------
 mm/hmm.c                |  5 ++--
 mm/memcontrol.c         |  2 +-
 mm/memory.c             | 10 ++++----
 mm/migrate.c            |  6 ++---
 mm/page_vma_mapped.c    |  6 ++---
 9 files changed, 30 insertions(+), 79 deletions(-)

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 18205f851c24..25c28d28ff61 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -691,7 +691,7 @@ static void ptep_zap_swap_entry(struct mm_struct *mm,
swp_entry_t entry)
 	if (!non_swap_entry(entry))
 		dec_mm_counter(mm, MM_SWAPENTS);
 	else if (is_migration_entry(entry)) {
-		struct page *page = migration_entry_to_page(entry);
+		struct page *page = pfn_to_page(swp_offset(entry));
 
 		dec_mm_counter(mm, mm_counter(page));
 	}
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 602e3a52884d..ee9686f96a41 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -514,10 +514,8 @@ static void smaps_pte_entry(pte_t *pte, unsigned long addr,
 			} else {
 				mss->swap_pss += (u64)PAGE_SIZE << PSS_SHIFT;
 			}
-		} else if (is_migration_entry(swpent))
-			page = migration_entry_to_page(swpent);
-		else if (is_device_private_entry(swpent))
-			page = device_private_entry_to_page(swpent);
+		} else if (is_special_entry(swpent))
+			page = pfn_to_page(swp_offset(swpent));
 	} else if (unlikely(IS_ENABLED(CONFIG_SHMEM) &&
mss->check_shmem_swap
 							&& pte_none(*pte))) {
 		page = xa_load(&vma->vm_file->f_mapping->i_pages,
@@ -549,7 +547,7 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr,
 		swp_entry_t entry = pmd_to_swp_entry(*pmd);
 
 		if (is_migration_entry(entry))
-			page = migration_entry_to_page(entry);
+			page = pfn_to_page(swp_offset(entry));
 	}
 	if (IS_ERR_OR_NULL(page))
 		return;
@@ -691,10 +689,8 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long
hmask,
 	} else if (is_swap_pte(*pte)) {
 		swp_entry_t swpent = pte_to_swp_entry(*pte);
 
-		if (is_migration_entry(swpent))
-			page = migration_entry_to_page(swpent);
-		else if (is_device_private_entry(swpent))
-			page = device_private_entry_to_page(swpent);
+		if (is_special_entry(swpent))
+			page = pfn_to_page(swp_offset(swpent));
 	}
 	if (page) {
 		int mapcount = page_mapcount(page);
@@ -1382,11 +1378,8 @@ static pagemap_entry_t pte_to_pagemap_entry(struct
pagemapread *pm,
 			frame = swp_type(entry) |
 				(swp_offset(entry) << MAX_SWAPFILES_SHIFT);
 		flags |= PM_SWAP;
-		if (is_migration_entry(entry))
-			page = migration_entry_to_page(entry);
-
-		if (is_device_private_entry(entry))
-			page = device_private_entry_to_page(entry);
+		if (is_special_entry(entry))
+			page = pfn_to_page(swp_offset(entry));
 	}
 
 	if (page && !PageAnon(page))
@@ -1443,7 +1436,7 @@ static int pagemap_pmd_range(pmd_t *pmdp, unsigned long
addr, unsigned long end,
 			if (pmd_swp_soft_dirty(pmd))
 				flags |= PM_SOFT_DIRTY;
 			VM_BUG_ON(!is_pmd_migration_entry(pmd));
-			page = migration_entry_to_page(entry);
+			page = pfn_to_page(swp_offset(entry));
 		}
 #endif
 
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 596bc2f4d9b0..729c44e7c270 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -519,8 +519,8 @@ static inline void show_swap_cache_info(void)
 {
 }
 
-#define free_swap_and_cache(e) ({(is_migration_entry(e) ||
is_device_private_entry(e));})
-#define swapcache_prepare(e) ({(is_migration_entry(e) ||
is_device_private_entry(e));})
+#define free_swap_and_cache(e) is_special_entry(e)
+#define swapcache_prepare(e) is_special_entry(e)
 
 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)
 {
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index d9b7c9132c2f..80cfa3985045 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -121,16 +121,6 @@ static inline bool
is_write_device_private_entry(swp_entry_t entry)
 {
 	return unlikely(swp_type(entry) == SWP_DEVICE_WRITE);
 }
-
-static inline unsigned long device_private_entry_to_pfn(swp_entry_t entry)
-{
-	return swp_offset(entry);
-}
-
-static inline struct page *device_private_entry_to_page(swp_entry_t entry)
-{
-	return pfn_to_page(swp_offset(entry));
-}
 #else /* CONFIG_DEVICE_PRIVATE */
 static inline swp_entry_t make_device_private_entry(struct page *page, bool
write)
 {
@@ -150,16 +140,6 @@ static inline bool
is_write_device_private_entry(swp_entry_t entry)
 {
 	return false;
 }
-
-static inline unsigned long device_private_entry_to_pfn(swp_entry_t entry)
-{
-	return 0;
-}
-
-static inline struct page *device_private_entry_to_page(swp_entry_t entry)
-{
-	return NULL;
-}
 #endif /* CONFIG_DEVICE_PRIVATE */
 
 #ifdef CONFIG_MIGRATION
@@ -182,22 +162,6 @@ static inline int is_write_migration_entry(swp_entry_t
entry)
 	return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
 }
 
-static inline unsigned long migration_entry_to_pfn(swp_entry_t entry)
-{
-	return swp_offset(entry);
-}
-
-static inline struct page *migration_entry_to_page(swp_entry_t entry)
-{
-	struct page *p = pfn_to_page(swp_offset(entry));
-	/*
-	 * Any use of migration entries may only occur while the
-	 * corresponding page is locked
-	 */
-	BUG_ON(!PageLocked(compound_head(p)));
-	return p;
-}
-
 static inline void make_migration_entry_read(swp_entry_t *entry)
 {
 	*entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
@@ -217,16 +181,6 @@ static inline int is_migration_entry(swp_entry_t swp)
 	return 0;
 }
 
-static inline unsigned long migration_entry_to_pfn(swp_entry_t entry)
-{
-	return 0;
-}
-
-static inline struct page *migration_entry_to_page(swp_entry_t entry)
-{
-	return NULL;
-}
-
 static inline void make_migration_entry_read(swp_entry_t *entryp) { }
 static inline void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
 					spinlock_t *ptl) { }
@@ -241,6 +195,11 @@ static inline int is_write_migration_entry(swp_entry_t
entry)
 
 #endif
 
+static inline bool is_special_entry(swp_entry_t entry)
+{
+	return is_migration_entry(entry) || is_device_private_entry(entry);
+}
+
 struct page_vma_mapped_walk;
 
 #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
diff --git a/mm/hmm.c b/mm/hmm.c
index 943cb2ba4442..b10494b18b65 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -214,7 +214,7 @@ static inline bool hmm_is_device_private_entry(struct
hmm_range *range,
 		swp_entry_t entry)
 {
 	return is_device_private_entry(entry) &&
-		device_private_entry_to_page(entry)->pgmap->owner =+	
pfn_to_page(swp_offset(entry))->pgmap->owner = 	
range->dev_private_owner;
 }
 
@@ -257,8 +257,7 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned
long addr,
 			cpu_flags = HMM_PFN_VALID;
 			if (is_write_device_private_entry(entry))
 				cpu_flags |= HMM_PFN_WRITE;
-			*hmm_pfn = device_private_entry_to_pfn(entry) |
-					cpu_flags;
+			*hmm_pfn = swp_offset(entry) | cpu_flags;
 			return 0;
 		}
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 913c2b9e5c72..1e6a318de8c2 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5544,7 +5544,7 @@ static struct page *mc_handle_swap_pte(struct
vm_area_struct *vma,
 	 * as special swap entry in the CPU page table.
 	 */
 	if (is_device_private_entry(ent)) {
-		page = device_private_entry_to_page(ent);
+		page = pfn_to_page(swp_offset(ent));
 		/*
 		 * MEMORY_DEVICE_PRIVATE means ZONE_DEVICE page and which have
 		 * a refcount of 1 when free (unlike normal page)
diff --git a/mm/memory.c b/mm/memory.c
index feff48e1465a..817d7a11ab7e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -718,7 +718,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct
mm_struct *src_mm,
 		}
 		rss[MM_SWAPENTS]++;
 	} else if (is_migration_entry(entry)) {
-		page = migration_entry_to_page(entry);
+		page = pfn_to_page(swp_offset(entry));
 
 		rss[mm_counter(page)]++;
 
@@ -737,7 +737,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct
mm_struct *src_mm,
 			set_pte_at(src_mm, addr, src_pte, pte);
 		}
 	} else if (is_device_private_entry(entry)) {
-		page = device_private_entry_to_page(entry);
+		page = pfn_to_page(swp_offset(entry));
 
 		/*
 		 * Update rss count even for unaddressable pages, as
@@ -1274,7 +1274,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 
 		entry = pte_to_swp_entry(ptent);
 		if (is_device_private_entry(entry)) {
-			struct page *page = device_private_entry_to_page(entry);
+			struct page *page = pfn_to_page(swp_offset(entry));
 
 			if (unlikely(details && details->check_mapping)) {
 				/*
@@ -1303,7 +1303,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 		else if (is_migration_entry(entry)) {
 			struct page *page;
 
-			page = migration_entry_to_page(entry);
+			page = pfn_to_page(swp_offset(entry));
 			rss[mm_counter(page)]--;
 		}
 		if (unlikely(!free_swap_and_cache(entry)))
@@ -3271,7 +3271,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 			migration_entry_wait(vma->vm_mm, vmf->pmd,
 					     vmf->address);
 		} else if (is_device_private_entry(entry)) {
-			vmf->page = device_private_entry_to_page(entry);
+			vmf->page = pfn_to_page(swp_offset(entry));
 			ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
 		} else if (is_hwpoison_entry(entry)) {
 			ret = VM_FAULT_HWPOISON;
diff --git a/mm/migrate.c b/mm/migrate.c
index 20ca887ea769..72adcc3d8f5b 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -321,7 +321,7 @@ void __migration_entry_wait(struct mm_struct *mm, pte_t
*ptep,
 	if (!is_migration_entry(entry))
 		goto out;
 
-	page = migration_entry_to_page(entry);
+	page = pfn_to_page(swp_offset(entry));
 
 	/*
 	 * Once page cache replacement of page migration started, page_count
@@ -361,7 +361,7 @@ void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t
*pmd)
 	ptl = pmd_lock(mm, pmd);
 	if (!is_pmd_migration_entry(*pmd))
 		goto unlock;
-	page = migration_entry_to_page(pmd_to_swp_entry(*pmd));
+	page = pfn_to_page(swp_offset(pmd_to_swp_entry(*pmd)));
 	if (!get_page_unless_zero(page))
 		goto unlock;
 	spin_unlock(ptl);
@@ -2437,7 +2437,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
 			if (!is_device_private_entry(entry))
 				goto next;
 
-			page = device_private_entry_to_page(entry);
+			page = pfn_to_page(swp_offset(entry));
 			if (!(migrate->flags &
 				MIGRATE_VMA_SELECT_DEVICE_PRIVATE) ||
 			    page->pgmap->owner != migrate->pgmap_owner)
diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index 86e3a3688d59..34230d08556a 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -96,7 +96,7 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw)
 		if (!is_migration_entry(entry))
 			return false;
 
-		pfn = migration_entry_to_pfn(entry);
+		pfn = swp_offset(entry);
 	} else if (is_swap_pte(*pvmw->pte)) {
 		swp_entry_t entry;
 
@@ -105,7 +105,7 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw)
 		if (!is_device_private_entry(entry))
 			return false;
 
-		pfn = device_private_entry_to_pfn(entry);
+		pfn = swp_offset(entry);
 	} else {
 		if (!pte_present(*pvmw->pte))
 			return false;
@@ -200,7 +200,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 				if (is_migration_entry(pmd_to_swp_entry(*pvmw->pmd))) {
 					swp_entry_t entry = pmd_to_swp_entry(*pvmw->pmd);
 
-					if (migration_entry_to_page(entry) != page)
+					if (pfn_to_page(swp_offset(entry)) != page)
 						return not_found(pvmw);
 					return true;
 				}
-- 
2.20.1

> -		struct page *page = migration_entry_to_page(entry);
> +		struct page *page = pfn_to_page(swp_offset(entry));
I wonder if keeping a single special_entry_to_page() helper would still
me a useful.  But I'm not entirely sure.  There are also two more open
coded copies of this in the THP migration code.
> -#define free_swap_and_cache(e) ({(is_migration_entry(e) ||
is_device_private_entry(e));})
> -#define swapcache_prepare(e) ({(is_migration_entry(e) ||
is_device_private_entry(e));})
> +#define free_swap_and_cache(e) is_special_entry(e)
> +#define swapcache_prepare(e) is_special_entry(e)
Staring at this I'm really, really confused at what this is doing.

Looking a little closer these are the !CONFIG_SWAP stubs, but it could
probably use a comment or two.
>  	} else if (is_migration_entry(entry)) {
> -		page = migration_entry_to_page(entry);
> +		page = pfn_to_page(swp_offset(entry));
>  
>  		rss[mm_counter(page)]++;
>  
> @@ -737,7 +737,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct
mm_struct *src_mm,
>  			set_pte_at(src_mm, addr, src_pte, pte);
>  		}
>  	} else if (is_device_private_entry(entry)) {
> -		page = device_private_entry_to_page(entry);
> +		page = pfn_to_page(swp_offset(entry));
>  
>  		/*
>  		 * Update rss count even for unaddressable pages, as
> @@ -1274,7 +1274,7 @@ static unsigned long zap_pte_range(struct mmu_gather
*tlb,
>  
>  		entry = pte_to_swp_entry(ptent);
>  		if (is_device_private_entry(entry)) {
> -			struct page *page = device_private_entry_to_page(entry);
> +			struct page *page = pfn_to_page(swp_offset(entry));
>  
>  			if (unlikely(details && details->check_mapping)) {
>  				/*
> @@ -1303,7 +1303,7 @@ static unsigned long zap_pte_range(struct mmu_gather
*tlb,
>  		else if (is_migration_entry(entry)) {
>  			struct page *page;
>  
> -			page = migration_entry_to_page(entry);
> +			page = pfn_to_page(swp_offset(entry));
>  			rss[mm_counter(page)]--;
>  		}
>  		if (unlikely(!free_swap_and_cache(entry)))
> @@ -3271,7 +3271,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
>  			migration_entry_wait(vma->vm_mm, vmf->pmd,
>  					     vmf->address);
>  		} else if (is_device_private_entry(entry)) {
> -			vmf->page = device_private_entry_to_page(entry);
> +			vmf->page = pfn_to_page(swp_offset(entry));
>  			ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
>  		} else if (is_hwpoison_entry(entry)) {
>  			ret = VM_FAULT_HWPOISON;
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 20ca887ea769..72adcc3d8f5b 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -321,7 +321,7 @@ void __migration_entry_wait(struct mm_struct *mm, pte_t
*ptep,
>  	if (!is_migration_entry(entry))
>  		goto out;
>  
> -	page = migration_entry_to_page(entry);
> +	page = pfn_to_page(swp_offset(entry));
>  
>  	/*
>  	 * Once page cache replacement of page migration started, page_count
> @@ -361,7 +361,7 @@ void pmd_migration_entry_wait(struct mm_struct *mm,
pmd_t *pmd)
>  	ptl = pmd_lock(mm, pmd);
>  	if (!is_pmd_migration_entry(*pmd))
>  		goto unlock;
> -	page = migration_entry_to_page(pmd_to_swp_entry(*pmd));
> +	page = pfn_to_page(swp_offset(pmd_to_swp_entry(*pmd)));
>  	if (!get_page_unless_zero(page))
>  		goto unlock;
>  	spin_unlock(ptl);
> @@ -2437,7 +2437,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
>  			if (!is_device_private_entry(entry))
>  				goto next;
>  
> -			page = device_private_entry_to_page(entry);
> +			page = pfn_to_page(swp_offset(entry));
>  			if (!(migrate->flags &
>  				MIGRATE_VMA_SELECT_DEVICE_PRIVATE) ||
>  			    page->pgmap->owner != migrate->pgmap_owner)
> diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
> index 86e3a3688d59..34230d08556a 100644
> --- a/mm/page_vma_mapped.c
> +++ b/mm/page_vma_mapped.c
> @@ -96,7 +96,7 @@ static bool check_pte(struct page_vma_mapped_walk *pvmw)
>  		if (!is_migration_entry(entry))
>  			return false;
>  
> -		pfn = migration_entry_to_pfn(entry);
> +		pfn = swp_offset(entry);
>  	} else if (is_swap_pte(*pvmw->pte)) {
>  		swp_entry_t entry;
>  
> @@ -105,7 +105,7 @@ static bool check_pte(struct page_vma_mapped_walk
*pvmw)
>  		if (!is_device_private_entry(entry))
>  			return false;
>  
> -		pfn = device_private_entry_to_pfn(entry);
> +		pfn = swp_offset(entry);
>  	} else {
>  		if (!pte_present(*pvmw->pte))
>  			return false;
> @@ -200,7 +200,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk
*pvmw)
>  				if (is_migration_entry(pmd_to_swp_entry(*pvmw->pmd))) {
>  					swp_entry_t entry = pmd_to_swp_entry(*pvmw->pmd);
>  
> -					if (migration_entry_to_page(entry) != page)
> +					if (pfn_to_page(swp_offset(entry)) != page)
>  						return not_found(pvmw);
>  					return true;
>  				}
> -- 
> 2.20.1
> 
---end quoted text---

On Saturday, 27 February 2021 2:59:09 AM AEDT Christoph Hellwig
wrote:
> > -		struct page *page = migration_entry_to_page(entry);
> > +		struct page *page = pfn_to_page(swp_offset(entry));
> 
> I wonder if keeping a single special_entry_to_page() helper would still
> me a useful.  But I'm not entirely sure.  There are also two more open
> coded copies of this in the THP migration code.
I think it might be if only to clearly document where these entries are used. 
Will add it for the next version to see what it looks like.
> > -#define free_swap_and_cache(e) ({(is_migration_entry(e) || 
is_device_private_entry(e));})
> > -#define swapcache_prepare(e) ({(is_migration_entry(e) || 
is_device_private_entry(e));})
> > +#define free_swap_and_cache(e) is_special_entry(e)
> > +#define swapcache_prepare(e) is_special_entry(e)
> 
> Staring at this I'm really, really confused at what this is doing.
> 
> Looking a little closer these are the !CONFIG_SWAP stubs, but it could
> probably use a comment or two.
Will do, thanks.

 - Alistair
 
> >  	} else if (is_migration_entry(entry)) {
> > -		page = migration_entry_to_page(entry);
> > +		page = pfn_to_page(swp_offset(entry));
> >  
> >  		rss[mm_counter(page)]++;
> >  
> > @@ -737,7 +737,7 @@ copy_nonpresent_pte(struct mm_struct *dst_mm,
struct
mm_struct *src_mm,
> >  			set_pte_at(src_mm, addr, src_pte, pte);
> >  		}
> >  	} else if (is_device_private_entry(entry)) {
> > -		page = device_private_entry_to_page(entry);
> > +		page = pfn_to_page(swp_offset(entry));
> >  
> >  		/*
> >  		 * Update rss count even for unaddressable pages, as
> > @@ -1274,7 +1274,7 @@ static unsigned long zap_pte_range(struct
mmu_gather
*tlb,
> >  
> >  		entry = pte_to_swp_entry(ptent);
> >  		if (is_device_private_entry(entry)) {
> > -			struct page *page = device_private_entry_to_page(entry);
> > +			struct page *page = pfn_to_page(swp_offset(entry));
> >  
> >  			if (unlikely(details && details->check_mapping)) {
> >  				/*
> > @@ -1303,7 +1303,7 @@ static unsigned long zap_pte_range(struct
mmu_gather
*tlb,
> >  		else if (is_migration_entry(entry)) {
> >  			struct page *page;
> >  
> > -			page = migration_entry_to_page(entry);
> > +			page = pfn_to_page(swp_offset(entry));
> >  			rss[mm_counter(page)]--;
> >  		}
> >  		if (unlikely(!free_swap_and_cache(entry)))
> > @@ -3271,7 +3271,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
> >  			migration_entry_wait(vma->vm_mm, vmf->pmd,
> >  					     vmf->address);
> >  		} else if (is_device_private_entry(entry)) {
> > -			vmf->page = device_private_entry_to_page(entry);
> > +			vmf->page = pfn_to_page(swp_offset(entry));
> >  			ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
> >  		} else if (is_hwpoison_entry(entry)) {
> >  			ret = VM_FAULT_HWPOISON;
> > diff --git a/mm/migrate.c b/mm/migrate.c
> > index 20ca887ea769..72adcc3d8f5b 100644
> > --- a/mm/migrate.c
> > +++ b/mm/migrate.c
> > @@ -321,7 +321,7 @@ void __migration_entry_wait(struct mm_struct *mm, 
pte_t *ptep,
> >  	if (!is_migration_entry(entry))
> >  		goto out;
> >  
> > -	page = migration_entry_to_page(entry);
> > +	page = pfn_to_page(swp_offset(entry));
> >  
> >  	/*
> >  	 * Once page cache replacement of page migration started, page_count
> > @@ -361,7 +361,7 @@ void pmd_migration_entry_wait(struct mm_struct
*mm,
pmd_t *pmd)
> >  	ptl = pmd_lock(mm, pmd);
> >  	if (!is_pmd_migration_entry(*pmd))
> >  		goto unlock;
> > -	page = migration_entry_to_page(pmd_to_swp_entry(*pmd));
> > +	page = pfn_to_page(swp_offset(pmd_to_swp_entry(*pmd)));
> >  	if (!get_page_unless_zero(page))
> >  		goto unlock;
> >  	spin_unlock(ptl);
> > @@ -2437,7 +2437,7 @@ static int migrate_vma_collect_pmd(pmd_t *pmdp,
> >  			if (!is_device_private_entry(entry))
> >  				goto next;
> >  
> > -			page = device_private_entry_to_page(entry);
> > +			page = pfn_to_page(swp_offset(entry));
> >  			if (!(migrate->flags &
> >  				MIGRATE_VMA_SELECT_DEVICE_PRIVATE) ||
> >  			    page->pgmap->owner != migrate->pgmap_owner)
> > diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
> > index 86e3a3688d59..34230d08556a 100644
> > --- a/mm/page_vma_mapped.c
> > +++ b/mm/page_vma_mapped.c
> > @@ -96,7 +96,7 @@ static bool check_pte(struct page_vma_mapped_walk
*pvmw)
> >  		if (!is_migration_entry(entry))
> >  			return false;
> >  
> > -		pfn = migration_entry_to_pfn(entry);
> > +		pfn = swp_offset(entry);
> >  	} else if (is_swap_pte(*pvmw->pte)) {
> >  		swp_entry_t entry;
> >  
> > @@ -105,7 +105,7 @@ static bool check_pte(struct page_vma_mapped_walk 
*pvmw)
> >  		if (!is_device_private_entry(entry))
> >  			return false;
> >  
> > -		pfn = device_private_entry_to_pfn(entry);
> > +		pfn = swp_offset(entry);
> >  	} else {
> >  		if (!pte_present(*pvmw->pte))
> >  			return false;
> > @@ -200,7 +200,7 @@ bool page_vma_mapped_walk(struct
page_vma_mapped_walk
*pvmw)
> >  				if (is_migration_entry(pmd_to_swp_entry(*pvmw->pmd))) {
> >  					swp_entry_t entry = pmd_to_swp_entry(*pvmw->pmd);
> >  
> > -					if (migration_entry_to_page(entry) != page)
> > +					if (pfn_to_page(swp_offset(entry)) != page)
> >  						return not_found(pvmw);
> >  					return true;
> >  				}
> ---end quoted text---
>