[PATCH v4 21/36] mm: Add __page_cache_alloc_order

Matthew Wilcox
2020-05-15T13:18:21Z

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

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@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 c75d7fb7ccbc..97f36ea16116 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -239,15 +239,33 @@ static inline int page_cache_add_speculative(struct page *page, int count)
return __page_cache_add_speculative(page, count);
}

+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 23a051a7ef0f..9abba062973a 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -941,24 +941,28 @@ 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