mm: try harder to allocate vmemmap blocks

Hot-adding memory on x86_64 normally requires huge page allocation.
When this is done to a VM guest, it's usually because the system is
already tight on memory, so the request tends to fail.  Try to avoid
this by adding __GFP_REPEAT to the allocation flags.

Addresses http://bugs.debian.org/699913Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Reported-by: NBernhard Schmidt <Bernhard.Schmidt@lrz.de>
Tested-by: NBernhard Schmidt <Bernhard.Schmidt@lrz.de>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/sparse-vmemmap.c

@@ -53,10 +53,12 @@ void * __meminit vmemmap_alloc_block(unsigned long size, int node)
 		struct page *page;
 
 		if (node_state(node, N_HIGH_MEMORY))
-			page = alloc_pages_node(node,
-				GFP_KERNEL | __GFP_ZERO, get_order(size));
+			page = alloc_pages_node(
+				node, GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
+				get_order(size));
 		else
-			page = alloc_pages(GFP_KERNEL | __GFP_ZERO,
+			page = alloc_pages(
+				GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
 				get_order(size));
 		if (page)
 			return page_address(page);