mm/page_alloc: Add folio allocation functions

The __folio_alloc(), __folio_alloc_node() and folio_alloc() functions
are mostly for type safety, but they also ensure that the page allocator
allocates a compound page and initialises the deferred list if the page
is large enough to have one.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>

1 files changed, 10 insertions, 0 deletions

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 1592b081c58e..251df91ddc80 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2202,6 +2202,16 @@ struct page *alloc_pages(gfp_t gfp, unsigned order)
 }
 EXPORT_SYMBOL(alloc_pages);
 
+struct folio *folio_alloc(gfp_t gfp, unsigned order)
+{
+	struct page *page = alloc_pages(gfp | __GFP_COMP, order);
+
+	if (page && order > 1)
+		prep_transhuge_page(page);
+	return (struct folio *)page;
+}
+EXPORT_SYMBOL(folio_alloc);
+
 int vma_dup_policy(struct vm_area_struct *src, struct vm_area_struct *dst)
 {
 	struct mempolicy *pol = mpol_dup(vma_policy(src));