[PATCH v6 34/51] mm: Add __page_cache_alloc_order

[Matthew Wilcox]

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

This new function allows page cache pages to be allocated that are
larger than an order-0 page.

Signed-off-by: Matthew Wilcox (Oracle) <wi...@infradead.org>
Acked-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
---
 include/linux/pagemap.h | 24 +++++++++++++++++++++---
 mm/filemap.c            | 12 ++++++++----
 2 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index f47ba9f18f3e..8455a3e16900 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -280,15 +280,33 @@ static inline void *detach_page_private(struct page *page)
        return data;
 }
 
+static inline gfp_t thp_gfpmask(gfp_t gfp)
+{
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+       /* We'd rather allocate smaller pages than stall a page fault */
+       gfp |= GFP_TRANSHUGE_LIGHT;
+       gfp &= ~__GFP_DIRECT_RECLAIM;
+#endif
+       return gfp;
+}
+
 #ifdef CONFIG_NUMA
-extern struct page *__page_cache_alloc(gfp_t gfp);
+extern struct page *__page_cache_alloc_order(gfp_t gfp, unsigned int order);
 #else
-static inline struct page *__page_cache_alloc(gfp_t gfp)
+static inline
+struct page *__page_cache_alloc_order(gfp_t gfp, unsigned int order)
 {
-       return alloc_pages(gfp, 0);
+       if (order == 0)
+               return alloc_pages(gfp, 0);
+       return prep_transhuge_page(alloc_pages(thp_gfpmask(gfp), order));
 }
 #endif
 
+static inline struct page *__page_cache_alloc(gfp_t gfp)
+{
+       return __page_cache_alloc_order(gfp, 0);
+}
+
 static inline struct page *page_cache_alloc(struct address_space *x)
 {
        return __page_cache_alloc(mapping_gfp_mask(x));
diff --git a/mm/filemap.c b/mm/filemap.c
index 80ce3658b147..3a9579a1ffa7 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -938,24 +938,28 @@ int add_to_page_cache_lru(struct page *page, struct 
address_space *mapping,
 EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
 
 #ifdef CONFIG_NUMA
-struct page *__page_cache_alloc(gfp_t gfp)
+struct page *__page_cache_alloc_order(gfp_t gfp, unsigned int order)
 {
        int n;
        struct page *page;
 
+       if (order > 0)
+               gfp = thp_gfpmask(gfp);
+
        if (cpuset_do_page_mem_spread()) {
                unsigned int cpuset_mems_cookie;
                do {
                        cpuset_mems_cookie = read_mems_allowed_begin();
                        n = cpuset_mem_spread_node();
-                       page = __alloc_pages_node(n, gfp, 0);
+                       page = __alloc_pages_node(n, gfp, order);
+                       prep_transhuge_page(page);
                } while (!page && read_mems_allowed_retry(cpuset_mems_cookie));
 
                return page;
        }
-       return alloc_pages(gfp, 0);
+       return prep_transhuge_page(alloc_pages(gfp, order));
 }
-EXPORT_SYMBOL(__page_cache_alloc);
+EXPORT_SYMBOL(__page_cache_alloc_order);
 #endif
 
 /*
-- 
2.26.2