readahead: readahead page allocations are OK to fail

Pass __GFP_NORETRY|__GFP_NOWARN for readahead page allocations.

readahead page allocations are completely optional.  They are OK to fail
and in particular shall not trigger OOM on themselves.

Reported-by: Dave Young <hidave.darkstar@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index ea26808..716875e 100644 (file)
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -219,6 +219,12 @@ static inline struct page *page_cache_alloc_cold(struct address_space *x)
        return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD);
 }
 
+static inline struct page *page_cache_alloc_readahead(struct address_space *x)
+{
+       return __page_cache_alloc(mapping_gfp_mask(x) |
+                                 __GFP_COLD | __GFP_NORETRY | __GFP_NOWARN);
+}
+
 typedef int filler_t(void *, struct page *);
 
 extern struct page * find_get_page(struct address_space *mapping,

diff --git a/mm/readahead.c b/mm/readahead.c
index 2c0cc48..867f9dd 100644 (file)
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -180,7 +180,7 @@ __do_page_cache_readahead(struct address_space *mapping, struct file *filp,
                if (page)
                        continue;
 
-               page = page_cache_alloc_cold(mapping);
+               page = page_cache_alloc_readahead(mapping);
                if (!page)
                        break;
                page->index = page_offset;