linux-kernel - [PATCH V9 3/7] mm/filemap: Extend __filemap_get

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Message-ID: <20250713174339.13981-6-shivankg@amd.com>
Date: Sun, 13 Jul 2025 17:43:37 +0000
From: Shivank Garg <shivankg@....com>
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Subject: [PATCH V9 3/7] mm/filemap: Extend __filemap_get_folio() to support NUMA memory policies

From: "Matthew Wilcox (Oracle)" <willy@...radead.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@....com>
Reviewed-by: Vlastimil Babka <vbabka@...e.cz>
Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Signed-off-by: Shivank Garg <shivankg@....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 78ea357d2077..981ff97b4445 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);
+}
+
 /**
  * filemap_get_folio - Find and get a folio.
  * @mapping: The address_space to search.
diff --git a/mm/filemap.c b/mm/filemap.c
index a30cd4dd085a..ec7de38c17c1 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1896,11 +1896,12 @@ 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.
  *
@@ -1911,8 +1912,8 @@ 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;
 
@@ -1982,7 +1983,7 @@ 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;
 
@@ -2029,7 +2030,7 @@ 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