[PATCH] mm: Try harder to allocate vmemmap blocks

[Ben Hutchings <ben@decadent.org.uk>]

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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.

Reported-and-tested-by: Bernhard Schmidt <Bernhard.Schmidt@lrz.de>
Reference: http://bugs.debian.org/699913
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
We could go even further and use __GFP_NOFAIL, but I'm not sure whether
that would be a good idea.

Ben.

 mm/sparse-vmemmap.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index 1b7e22a..22b7e18 100644
--- a/mm/sparse-vmemmap.c
+++ b/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);


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