Re: [PATCH 1/2] mm: remove page_rmapping()

Sidhartha Kumar
2023-06-30T16:05:19Z

On 6/30/23 5:13 AM, 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>
> ---
> include/linux/mm.h | 1 -
> mm/memory.c | 2 +-
> mm/util.c | 6 ------
> 3 files changed, 1 insertion(+), 8 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 9ecb8b9c07f6..8c7eba7370b2 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2129,7 +2129,6 @@ 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/memory.c b/mm/memory.c
> index 21fab2727209..6921df44a99f 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2979,7 +2979,7 @@ static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
> * pinned by vma->vm_file's reference. We rely on unlock_page()'s
> * release semantics to prevent the compiler from undoing this copying.
> */

struct page *page = vmf->page;

...

dirtied = set_page_dirty(page);
VM_BUG_ON_PAGE(PageAnon(page), page);

Can this earlier part of the function be converted to folios so a folio
can be passed directly in folio_raw_mapping()?
> - mapping = page_rmapping(page);
> + mapping = folio_raw_mapping(page_folio(page));
> unlock_page(page);
>
> if (!page_mkwrite)
> 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;