fs/ramfs/file-nommu.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
Currently, ramfs_nommu_expand_for_mapping() utilizes the deprecated
alloc_pages() API. This patch converts the allocation step to use
the modern folio_alloc() API, removing a legacy caller and helping
pave the way for the eventual removal of alloc_pages().
Because nommu architectures require physically contiguous memory that
often needs to be trimmed to the exact requested size, the allocated
folio is immediately shattered using split_page().
Since split_page() destroys the compound folio metadata, using folio
iteration helpers (like folio_page) becomes unsafe. Therefore, this
patch deliberately drops back to a standard struct page array after
the split. This safely isolates the folio conversion to the allocation
phase while strictly preserving the existing trimming and page cache
insertion behavior.
Signed-off-by: AnishMulay <anishm7030@gmail.com>
---
fs/ramfs/file-nommu.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/ramfs/file-nommu.c b/fs/ramfs/file-nommu.c
index 77b8ca2757e0d..767de8fc56f0f 100644
--- a/fs/ramfs/file-nommu.c
+++ b/fs/ramfs/file-nommu.c
@@ -62,6 +62,7 @@ const struct inode_operations ramfs_file_inode_operations = {
int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
{
unsigned long npages, xpages, loop;
+ struct folio *folio;
struct page *pages;
unsigned order;
void *data;
@@ -81,10 +82,12 @@ int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
/* allocate enough contiguous pages to be able to satisfy the
* request */
- pages = alloc_pages(gfp, order);
- if (!pages)
+ folio = folio_alloc(gfp, order);
+ if (!folio)
return -ENOMEM;
+ pages = &folio->page;
+
/* split the high-order page into an array of single pages */
xpages = 1UL << order;
npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
--
2.51.0CC: linux-fsdevel@vger.kernel.org
On Tue, 2026-02-24 at 15:31 -0500, AnishMulay wrote:
> Currently, ramfs_nommu_expand_for_mapping() utilizes the deprecated
> alloc_pages() API. This patch converts the allocation step to use
> the modern folio_alloc() API, removing a legacy caller and helping
> pave the way for the eventual removal of alloc_pages().
>
> Because nommu architectures require physically contiguous memory that
> often needs to be trimmed to the exact requested size, the allocated
> folio is immediately shattered using split_page().
>
> Since split_page() destroys the compound folio metadata, using folio
> iteration helpers (like folio_page) becomes unsafe. Therefore, this
> patch deliberately drops back to a standard struct page array after
> the split. This safely isolates the folio conversion to the allocation
> phase while strictly preserving the existing trimming and page cache
> insertion behavior.
>
> Signed-off-by: AnishMulay <anishm7030@gmail.com>
> ---
> fs/ramfs/file-nommu.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ramfs/file-nommu.c b/fs/ramfs/file-nommu.c
> index 77b8ca2757e0d..767de8fc56f0f 100644
> --- a/fs/ramfs/file-nommu.c
> +++ b/fs/ramfs/file-nommu.c
> @@ -62,6 +62,7 @@ const struct inode_operations ramfs_file_inode_operations = {
> int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
This method uses old page concept everywhere. If you would like to switch this
method for using the folio concept, then I assume this method requires more
rework.
Thanks,
Slava.
> {
> unsigned long npages, xpages, loop;
> + struct folio *folio;
> struct page *pages;
> unsigned order;
> void *data;
> @@ -81,10 +82,12 @@ int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
>
> /* allocate enough contiguous pages to be able to satisfy the
> * request */
> - pages = alloc_pages(gfp, order);
> - if (!pages)
> + folio = folio_alloc(gfp, order);
> + if (!folio)
> return -ENOMEM;
>
> + pages = &folio->page;
> +
> /* split the high-order page into an array of single pages */
> xpages = 1UL << order;
> npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
On Wed, Feb 25, 2026 at 06:44:28PM +0000, Viacheslav Dubeyko wrote: > CC: linux-fsdevel@vger.kernel.org Good plan. > On Tue, 2026-02-24 at 15:31 -0500, AnishMulay wrote: > > Currently, ramfs_nommu_expand_for_mapping() utilizes the deprecated > > alloc_pages() API. This patch converts the allocation step to use alloc_pages() is not deprecated. There are no plans for its removal. > > the modern folio_alloc() API, removing a legacy caller and helping > > pave the way for the eventual removal of alloc_pages(). > > > > Because nommu architectures require physically contiguous memory that > > often needs to be trimmed to the exact requested size, the allocated > > folio is immediately shattered using split_page(). Except that split_page() doesn't work on folios. It says so right there in the documentation: * split_page takes a non-compound higher-order page, and splits it into Folios are compound pages. This should have told you that you were going the wrong thing. > > Since split_page() destroys the compound folio metadata, using folio > > iteration helpers (like folio_page) becomes unsafe. Therefore, this > > patch deliberately drops back to a standard struct page array after > > the split. This safely isolates the folio conversion to the allocation > > phase while strictly preserving the existing trimming and page cache > > insertion behavior. Please stop trying to help, particularly for code you can't test.
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