[PATCH] mm/migrate: rename PAGE_ migration flags to FOLIO_MF_

[PATCH] mm/migrate: rename PAGE_ migration flags to FOLIO_MF_

[Shivank Garg]

These flags only track folio-specific state during migration and are
not used for movable_ops pages. Rename the enum values and the
old_page_state variable to match.

No functional change.

Suggested-by: David Hildenbrand <david@kernel.org>
Signed-off-by: Shivank Garg <shivankg@amd.com>
---
Applies cleanly on mm-new

Ref: https://lore.kernel.org/linux-mm/4bfec2c1-9747-49d2-a490-87ab204cec1c@kernel.org

 mm/migrate.c | 46 +++++++++++++++++++++++-----------------------
 1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 05cb408846f2..a1856321ae27 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1135,26 +1135,26 @@ static int move_to_new_folio(struct folio *dst, struct folio *src,
  * This is safe because nobody is using it except us.
  */
 enum {
-	PAGE_WAS_MAPPED = BIT(0),
-	PAGE_WAS_MLOCKED = BIT(1),
-	PAGE_OLD_STATES = PAGE_WAS_MAPPED | PAGE_WAS_MLOCKED,
+	FOLIO_MF_WAS_MAPPED = BIT(0),
+	FOLIO_MF_WAS_MLOCKED = BIT(1),
+	FOLIO_MF_OLD_STATES = FOLIO_MF_WAS_MAPPED | FOLIO_MF_WAS_MLOCKED,
 };
 
 static void __migrate_folio_record(struct folio *dst,
-				   int old_page_state,
+				   int old_folio_state,
 				   struct anon_vma *anon_vma)
 {
-	dst->private = (void *)anon_vma + old_page_state;
+	dst->private = (void *)anon_vma + old_folio_state;
 }
 
 static void __migrate_folio_extract(struct folio *dst,
-				   int *old_page_state,
+				   int *old_folio_state,
 				   struct anon_vma **anon_vmap)
 {
 	unsigned long private = (unsigned long)dst->private;
 
-	*anon_vmap = (struct anon_vma *)(private & ~PAGE_OLD_STATES);
-	*old_page_state = private & PAGE_OLD_STATES;
+	*anon_vmap = (struct anon_vma *)(private & ~FOLIO_MF_OLD_STATES);
+	*old_folio_state = private & FOLIO_MF_OLD_STATES;
 	dst->private = NULL;
 }
 
@@ -1209,7 +1209,7 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
 {
 	struct folio *dst;
 	int rc = -EAGAIN;
-	int old_page_state = 0;
+	int old_folio_state = 0;
 	struct anon_vma *anon_vma = NULL;
 	bool locked = false;
 	bool dst_locked = false;
@@ -1253,7 +1253,7 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
 	}
 	locked = true;
 	if (folio_test_mlocked(src))
-		old_page_state |= PAGE_WAS_MLOCKED;
+		old_folio_state |= FOLIO_MF_WAS_MLOCKED;
 
 	if (folio_test_writeback(src)) {
 		/*
@@ -1302,7 +1302,7 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
 	dst_locked = true;
 
 	if (unlikely(page_has_movable_ops(&src->page))) {
-		__migrate_folio_record(dst, old_page_state, anon_vma);
+		__migrate_folio_record(dst, old_folio_state, anon_vma);
 		return 0;
 	}
 
@@ -1328,11 +1328,11 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
 		VM_BUG_ON_FOLIO(folio_test_anon(src) &&
 			       !folio_test_ksm(src) && !anon_vma, src);
 		try_to_migrate(src, mode == MIGRATE_ASYNC ? TTU_BATCH_FLUSH : 0);
-		old_page_state |= PAGE_WAS_MAPPED;
+		old_folio_state |= FOLIO_MF_WAS_MAPPED;
 	}
 
 	if (!folio_mapped(src)) {
-		__migrate_folio_record(dst, old_page_state, anon_vma);
+		__migrate_folio_record(dst, old_folio_state, anon_vma);
 		return 0;
 	}
 
@@ -1344,7 +1344,7 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
 	if (rc == -EAGAIN)
 		ret = NULL;
 
-	migrate_folio_undo_src(src, old_page_state & PAGE_WAS_MAPPED,
+	migrate_folio_undo_src(src, old_folio_state & FOLIO_MF_WAS_MAPPED,
 			       anon_vma, locked, ret);
 	migrate_folio_undo_dst(dst, dst_locked, put_new_folio, private);
 
@@ -1358,13 +1358,13 @@ static int migrate_folio_move(free_folio_t put_new_folio, unsigned long private,
 			      struct list_head *ret)
 {
 	int rc;
-	int old_page_state = 0;
+	int old_folio_state = 0;
 	struct anon_vma *anon_vma = NULL;
 	bool src_deferred_split = false;
 	bool src_partially_mapped = false;
 	struct list_head *prev;
 
-	__migrate_folio_extract(dst, &old_page_state, &anon_vma);
+	__migrate_folio_extract(dst, &old_folio_state, &anon_vma);
 	prev = dst->lru.prev;
 	list_del(&dst->lru);
 
@@ -1395,10 +1395,10 @@ static int migrate_folio_move(free_folio_t put_new_folio, unsigned long private,
 	 * isolated from the unevictable LRU: but this case is the easiest.
 	 */
 	folio_add_lru(dst);
-	if (old_page_state & PAGE_WAS_MLOCKED)
+	if (old_folio_state & FOLIO_MF_WAS_MLOCKED)
 		lru_add_drain();
 
-	if (old_page_state & PAGE_WAS_MAPPED)
+	if (old_folio_state & FOLIO_MF_WAS_MAPPED)
 		remove_migration_ptes(src, dst, 0);
 
 	/*
@@ -1439,11 +1439,11 @@ static int migrate_folio_move(free_folio_t put_new_folio, unsigned long private,
 	 */
 	if (rc == -EAGAIN) {
 		list_add(&dst->lru, prev);
-		__migrate_folio_record(dst, old_page_state, anon_vma);
+		__migrate_folio_record(dst, old_folio_state, anon_vma);
 		return rc;
 	}
 
-	migrate_folio_undo_src(src, old_page_state & PAGE_WAS_MAPPED,
+	migrate_folio_undo_src(src, old_folio_state & FOLIO_MF_WAS_MAPPED,
 			       anon_vma, true, ret);
 	migrate_folio_undo_dst(dst, true, put_new_folio, private);
 
@@ -1777,11 +1777,11 @@ static void migrate_folios_undo(struct list_head *src_folios,
 	dst = list_first_entry(dst_folios, struct folio, lru);
 	dst2 = list_next_entry(dst, lru);
 	list_for_each_entry_safe(folio, folio2, src_folios, lru) {
-		int old_page_state = 0;
+		int old_folio_state = 0;
 		struct anon_vma *anon_vma = NULL;
 
-		__migrate_folio_extract(dst, &old_page_state, &anon_vma);
-		migrate_folio_undo_src(folio, old_page_state & PAGE_WAS_MAPPED,
+		__migrate_folio_extract(dst, &old_folio_state, &anon_vma);
+		migrate_folio_undo_src(folio, old_folio_state & FOLIO_MF_WAS_MAPPED,
 				anon_vma, true, ret_folios);
 		list_del(&dst->lru);
 		migrate_folio_undo_dst(dst, true, put_new_folio, private);
-- 
2.43.0

Re: [PATCH] mm/migrate: rename PAGE_ migration flags to FOLIO_MF_

[Matthew Wilcox]

On Mon, Mar 23, 2026 at 02:19:37PM +0000, Shivank Garg wrote:
> +++ b/mm/migrate.c
> @@ -1135,26 +1135,26 @@ static int move_to_new_folio(struct folio *dst, struct folio *src,
>   * This is safe because nobody is using it except us.
>   */
>  enum {
> -	PAGE_WAS_MAPPED = BIT(0),
> -	PAGE_WAS_MLOCKED = BIT(1),
> -	PAGE_OLD_STATES = PAGE_WAS_MAPPED | PAGE_WAS_MLOCKED,
> +	FOLIO_MF_WAS_MAPPED = BIT(0),
> +	FOLIO_MF_WAS_MLOCKED = BIT(1),
> +	FOLIO_MF_OLD_STATES = FOLIO_MF_WAS_MAPPED | FOLIO_MF_WAS_MLOCKED,

what does 'MF' stand for?  i mean, presumably not the pop culture
meaning of MF ...

>  	locked = true;
>  	if (folio_test_mlocked(src))
> -		old_page_state |= PAGE_WAS_MLOCKED;
> +		old_folio_state |= FOLIO_MF_WAS_MLOCKED;

I mean, this doesn't make sense any more.  PAGE_WAS_MLOCKED is a
sentence that means something.  FOLIO_MF_WAS_MLOCKED doesn't ... unless
you imagine Samuel L Jackson saying it ...

Re: [PATCH] mm/migrate: rename PAGE_ migration flags to FOLIO_MF_

[David Hildenbrand (Arm)]

On 3/23/26 15:46, Matthew Wilcox wrote:
> On Mon, Mar 23, 2026 at 02:19:37PM +0000, Shivank Garg wrote:
>> +++ b/mm/migrate.c
>> @@ -1135,26 +1135,26 @@ static int move_to_new_folio(struct folio *dst, struct folio *src,
>>   * This is safe because nobody is using it except us.
>>   */
>>  enum {
>> -	PAGE_WAS_MAPPED = BIT(0),
>> -	PAGE_WAS_MLOCKED = BIT(1),
>> -	PAGE_OLD_STATES = PAGE_WAS_MAPPED | PAGE_WAS_MLOCKED,
>> +	FOLIO_MF_WAS_MAPPED = BIT(0),
>> +	FOLIO_MF_WAS_MLOCKED = BIT(1),
>> +	FOLIO_MF_OLD_STATES = FOLIO_MF_WAS_MAPPED | FOLIO_MF_WAS_MLOCKED,
> 
> what does 'MF' stand for?  i mean, presumably not the pop culture
> meaning of MF ...

Migration FLag

> 
>>  	locked = true;
>>  	if (folio_test_mlocked(src))
>> -		old_page_state |= PAGE_WAS_MLOCKED;
>> +		old_folio_state |= FOLIO_MF_WAS_MLOCKED;
> 
> I mean, this doesn't make sense any more.  PAGE_WAS_MLOCKED is a
> sentence that means something.  FOLIO_MF_WAS_MLOCKED doesn't ... unless
> you imagine Samuel L Jackson saying it ...

:)

PAGE_WAS_MLOCKED was suboptimal given that the names overlap with things
like PAGE_SHARED or even PAGE_IS_PRESENT.

So using some prefix to indicate that these flag belong logically
together makes sense. Even if it's not a beautiful sentence.

FOLIO_MIGRATION_* could be done, but "FOLIO_MIGRATION_WAS_MLOCKED" is
also does not make sense. FOLIO_MIGRATION_FLAG_* is mouthful.

-- 
Cheers,

David

Re: [PATCH] mm/migrate: rename PAGE_ migration flags to FOLIO_MF_

[Matthew Wilcox]

On Mon, Mar 23, 2026 at 04:36:38PM +0100, David Hildenbrand (Arm) wrote:
> On 3/23/26 15:46, Matthew Wilcox wrote:
> >>  	if (folio_test_mlocked(src))
> >> -		old_page_state |= PAGE_WAS_MLOCKED;
> >> +		old_folio_state |= FOLIO_MF_WAS_MLOCKED;
> > 
> > I mean, this doesn't make sense any more.  PAGE_WAS_MLOCKED is a
> > sentence that means something.  FOLIO_MF_WAS_MLOCKED doesn't ... unless
> > you imagine Samuel L Jackson saying it ...
> 
> :)
> 
> PAGE_WAS_MLOCKED was suboptimal given that the names overlap with things
> like PAGE_SHARED or even PAGE_IS_PRESENT.

PAGE_SHARED (and friends) are misnamed because really they're PTE flags,
not page flags.  Then PAGE_IS_* form a namespace for pagemap, which I
think is fine.  These are PAGE_WAS, so a distinct namespace already.

> So using some prefix to indicate that these flag belong logically
> together makes sense. Even if it's not a beautiful sentence.

FOLIO_WAS_ seems like a fine namespace.  Especially since it's local to
this file.

Re: [PATCH] mm/migrate: rename PAGE_ migration flags to FOLIO_MF_

[David Hildenbrand (Arm)]

On 3/23/26 19:57, Matthew Wilcox wrote:
> On Mon, Mar 23, 2026 at 04:36:38PM +0100, David Hildenbrand (Arm) wrote:
>> On 3/23/26 15:46, Matthew Wilcox wrote:
>>>
>>> I mean, this doesn't make sense any more.  PAGE_WAS_MLOCKED is a
>>> sentence that means something.  FOLIO_MF_WAS_MLOCKED doesn't ... unless
>>> you imagine Samuel L Jackson saying it ...
>>
>> :)
>>
>> PAGE_WAS_MLOCKED was suboptimal given that the names overlap with things
>> like PAGE_SHARED or even PAGE_IS_PRESENT.
> 
> PAGE_SHARED (and friends) are misnamed because really they're PTE flags,
> not page flags.  Then PAGE_IS_* form a namespace for pagemap, which I
> think is fine.  These are PAGE_WAS, so a distinct namespace already.
> 
>> So using some prefix to indicate that these flag belong logically
>> together makes sense. Even if it's not a beautiful sentence.
> 
> FOLIO_WAS_ seems like a fine namespace.  Especially since it's local to
> this file.

Right, given that it's local to the file that's ok.

-- 
Cheers,

David

Re: [PATCH] mm/migrate: rename PAGE_ migration flags to FOLIO_MF_

[Garg, Shivank]

On 3/24/2026 12:51 AM, David Hildenbrand (Arm) wrote:
> On 3/23/26 19:57, Matthew Wilcox wrote:
>> On Mon, Mar 23, 2026 at 04:36:38PM +0100, David Hildenbrand (Arm) wrote:
>>> On 3/23/26 15:46, Matthew Wilcox wrote:
>>>>
>>>> I mean, this doesn't make sense any more.  PAGE_WAS_MLOCKED is a
>>>> sentence that means something.  FOLIO_MF_WAS_MLOCKED doesn't ... unless
>>>> you imagine Samuel L Jackson saying it ...
>>>
>>> :)
>>>
>>> PAGE_WAS_MLOCKED was suboptimal given that the names overlap with things
>>> like PAGE_SHARED or even PAGE_IS_PRESENT.
>>
>> PAGE_SHARED (and friends) are misnamed because really they're PTE flags,
>> not page flags.  Then PAGE_IS_* form a namespace for pagemap, which I
>> think is fine.  These are PAGE_WAS, so a distinct namespace already.
>>
>>> So using some prefix to indicate that these flag belong logically
>>> together makes sense. Even if it's not a beautiful sentence.
>>
>> FOLIO_WAS_ seems like a fine namespace.  Especially since it's local to
>> this file.
> 
> Right, given that it's local to the file that's ok.
> 

Thanks, I will send V2 with FOLIO_WAS_*.

Best regards,
Shivank