[PATCH v2 0/2] mm: remove page_rmapping()

[PATCH v2 0/2] mm: remove page_rmapping()

[Peng Zhang]

From: ZhangPeng <zhangpeng362@huawei.com>

This minor patch series convert fault_dirty_shared_page() to use a folio
first, then remove the now-unused page_rmapping().

Change log:

v2:
- reverse the order of the two patches
- add RBs from Sidhartha Kumar
- update comment

ZhangPeng (2):
  mm: use a folio in fault_dirty_shared_page()
  mm: remove page_rmapping()

 include/linux/mm.h |  1 -
 mm/memory.c        | 16 ++++++++--------
 mm/util.c          |  6 ------
 3 files changed, 8 insertions(+), 15 deletions(-)

-- 
2.25.1

[PATCH v2 1/2] mm: use a folio in fault_dirty_shared_page()

[Peng Zhang]

From: ZhangPeng <zhangpeng362@huawei.com>

We can replace four implicit calls to compound_head() with one by using
folio.

Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
---
 mm/memory.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 765e5d8ed1f4..9a2f4dab872f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2968,20 +2968,20 @@ static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct address_space *mapping;
-	struct page *page = vmf->page;
+	struct folio *folio = page_folio(vmf->page);
 	bool dirtied;
 	bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
 
-	dirtied = set_page_dirty(page);
-	VM_BUG_ON_PAGE(PageAnon(page), page);
+	dirtied = folio_mark_dirty(folio);
+	VM_BUG_ON_FOLIO(folio_test_anon(folio), folio);
 	/*
-	 * Take a local copy of the address_space - page.mapping may be zeroed
-	 * by truncate after unlock_page().   The address_space itself remains
-	 * pinned by vma->vm_file's reference.  We rely on unlock_page()'s
+	 * Take a local copy of the address_space - folio.mapping may be zeroed
+	 * by truncate after folio_unlock().   The address_space itself remains
+	 * pinned by vma->vm_file's reference.  We rely on folio_unlock()'s
 	 * release semantics to prevent the compiler from undoing this copying.
 	 */
-	mapping = page_rmapping(page);
-	unlock_page(page);
+	mapping = folio_raw_mapping(folio);
+	folio_unlock(folio);
 
 	if (!page_mkwrite)
 		file_update_time(vma->vm_file);
-- 
2.25.1

Re: [PATCH v2 1/2] mm: use a folio in fault_dirty_shared_page()

[Matthew Wilcox]

On Sat, Jul 01, 2023 at 11:28:52AM +0800, Peng Zhang wrote:
> From: ZhangPeng <zhangpeng362@huawei.com>
> 
> We can replace four implicit calls to compound_head() with one by using
> folio.
> 
> Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
> Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>

[PATCH v2 2/2] mm: remove page_rmapping()

[Peng Zhang]

From: ZhangPeng <zhangpeng362@huawei.com>

After converting the last user to folio_raw_mapping(), we can safely
remove the function.

Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
---
 include/linux/mm.h | 1 -
 mm/util.c          | 6 ------
 2 files changed, 7 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 39aa409e84d5..c849419c6b51 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2151,7 +2151,6 @@ static inline void *folio_address(const struct folio *folio)
 	return page_address(&folio->page);
 }
 
-extern void *page_rmapping(struct page *page);
 extern pgoff_t __page_file_index(struct page *page);
 
 /*
diff --git a/mm/util.c b/mm/util.c
index dd12b9531ac4..5e9305189c3f 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -734,12 +734,6 @@ void *vcalloc(size_t n, size_t size)
 }
 EXPORT_SYMBOL(vcalloc);
 
-/* Neutral page->mapping pointer to address_space or anon_vma or other */
-void *page_rmapping(struct page *page)
-{
-	return folio_raw_mapping(page_folio(page));
-}
-
 struct anon_vma *folio_anon_vma(struct folio *folio)
 {
 	unsigned long mapping = (unsigned long)folio->mapping;
-- 
2.25.1

Re: [PATCH v2 2/2] mm: remove page_rmapping()

[Matthew Wilcox]

On Sat, Jul 01, 2023 at 11:28:53AM +0800, Peng Zhang wrote:
> From: ZhangPeng <zhangpeng362@huawei.com>
> 
> After converting the last user to folio_raw_mapping(), we can safely
> remove the function.
> 
> Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
> Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>

Thank you!

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>