[PATCH] handle radix_tree_node allocation failures

This patch uses the radix_tree_preload() API in add_to_page_cache().

A new gfp_mask argument is added to add_to_page_cache(), which is then passed
on to radix_tree_preload().   It's pretty simple.

In the case of adding pages to swapcache we're still using GFP_ATOMIC, so
these addition attempts can still fail.  That's OK, because the error is
handled and, unlike file pages, it will not cause user applicaton failures.
This codepath (radix-tree node exhaustion on swapout) was well tested in the
days when the swapper_space radix tree was fragmented all over the place due
to unfortunate swp_entry bit layout.

1 files changed, 4 insertions, 4 deletions

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 9707f467b2be..1a297ca9d00a 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -66,10 +66,10 @@ extern struct page * read_cache_page(struct address_space *mapping,
 extern int read_cache_pages(struct address_space *mapping,
 		struct list_head *pages, filler_t *filler, void *data);
 
-extern int add_to_page_cache(struct page *page,
-		struct address_space *mapping, unsigned long index);
-extern int add_to_page_cache_lru(struct page *page,
-		struct address_space *mapping, unsigned long index);
+int add_to_page_cache(struct page *page, struct address_space *mapping,
+				unsigned long index, int gfp_mask);
+int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
+				unsigned long index, int gfp_mask);
 extern void remove_from_page_cache(struct page *page);
 extern void __remove_from_page_cache(struct page *page);