[PATCH kvm-next V11 2/7] mm/filemap: Extend __filemap_get_folio() to support NUMA memory policies

Shivank Garg
2025-08-27T17:56:16Z

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

Extend __filemap_get_folio() to support NUMA memory policies by
renaming the implementation to __filemap_get_folio_mpol() and adding
a mempolicy parameter. The original function becomes a static inline
wrapper that passes NULL for the mempolicy.

This infrastructure will enable future support for NUMA-aware page cache
allocations in guest_memfd memory backend KVM guests.

Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Shivank Garg <shivankg@amd.com>
---
include/linux/pagemap.h | 10 ++++++++--
mm/filemap.c | 11 ++++++-----
2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index ce617a35dc35..94d65ced0a1d 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -747,11 +747,17 @@ static inline fgf_t fgf_set_order(size_t size)
}

void *filemap_get_entry(struct address_space *mapping, pgoff_t index);
-struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
- fgf_t fgp_flags, gfp_t gfp);
+struct folio *__filemap_get_folio_mpol(struct address_space *mapping,
+ pgoff_t index, fgf_t fgf_flags, gfp_t gfp, struct mempolicy *policy);
struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
fgf_t fgp_flags, gfp_t gfp);

+static inline struct folio *__filemap_get_folio(struct address_space *mapping,
+ pgoff_t index, fgf_t fgf_flags, gfp_t gfp)
+{
+ return __filemap_get_folio_mpol(mapping, index, fgf_flags, gfp, NULL);
+}
+
/**
* write_begin_get_folio - Get folio for write_begin with flags.
* @iocb: The kiocb passed from write_begin (may be NULL).
diff --git a/mm/filemap.c b/mm/filemap.c
index 495f7f5c3d2e..03f223be575c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1897,11 +1897,12 @@ void *filemap_get_entry(struct address_space *mapping, pgoff_t index)
}

/**
- * __filemap_get_folio - Find and get a reference to a folio.
+ * __filemap_get_folio_mpol - Find and get a reference to a folio.
* @mapping: The address_space to search.
* @index: The page index.
* @fgp_flags: %FGP flags modify how the folio is returned.
* @gfp: Memory allocation flags to use if %FGP_CREAT is specified.
+ * @policy: NUMA memory allocation policy to follow.
*
* Looks up the page cache entry at @mapping & @index.
*
@@ -1912,8 +1913,8 @@ void *filemap_get_entry(struct address_space *mapping, pgoff_t index)
*
* Return: The found folio or an ERR_PTR() otherwise.
*/
-struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
- fgf_t fgp_flags, gfp_t gfp)
+struct folio *__filemap_get_folio_mpol(struct address_space *mapping,
+ pgoff_t index, fgf_t fgp_flags, gfp_t gfp, struct mempolicy *policy)
{
struct folio *folio;

@@ -1983,7 +1984,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
err = -ENOMEM;
if (order > min_order)
alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN;
- folio = filemap_alloc_folio(alloc_gfp, order, NULL);
+ folio = filemap_alloc_folio(alloc_gfp, order, policy);
if (!folio)
continue;

@@ -2030,7 +2031,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
folio_clear_dropbehind(folio);
return folio;
}
-EXPORT_SYMBOL(__filemap_get_folio);
+EXPORT_SYMBOL(__filemap_get_folio_mpol);

static inline struct folio *find_get_entry(struct xa_state *xas, pgoff_t max,
xa_mark_t mark)
--
2.43.0