[PATCH] hugetlb: restore interleaving of bootmem huge pages

[Lee Schermerhorn <Lee.Schermerhorn@hp.com>]

PATCH restore interleaving of bootmem huge pages

Against: 2.6.31-rc1-mmotm-090625-1549
atop the "hugetlb-balance-freeing-of-huge-pages-across-node" series

I noticed that alloc_bootmem_huge_page() will only advance to the
next node on failure to allocate a huge page, potentially filling 
nodes with huge-pages.  I asked about this on linux-mm and linux-numa,
cc'ing the usual huge page suspects.

Mel Gorman responded:

	I strongly suspect that the same node being used until allocation
	failure instead of round-robin is an oversight and not deliberate
	at all. It appears to be a side-effect of a fix made way back in
	commit 63b4613c3f0d4b724ba259dc6c201bb68b884e1a ["hugetlb: fix
	hugepage allocation with memoryless nodes"]. Prior to that patch
	it looked like allocations would always round-robin even when
	allocation was successful.

This patch--factored out of my "hugetlb mempolicy" series--moves the
advance of the hstate next node from which to allocate up before the
test for success of the attempted allocation.

Note that alloc_bootmem_huge_page() is only used for order > MAX_ORDER
huge pages.

I'll post a separate patch for mainline/stable, as the above mentioned
"balance freeing" series renamed the next node to alloc function.

Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>

 mm/hugetlb.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6.31-rc1-mmotm-090625-1549/mm/hugetlb.c
===================================================================
--- linux-2.6.31-rc1-mmotm-090625-1549.orig/mm/hugetlb.c	2009-07-13 09:05:22.000000000 -0400
+++ linux-2.6.31-rc1-mmotm-090625-1549/mm/hugetlb.c	2009-07-13 09:06:22.000000000 -0400
@@ -1030,6 +1030,7 @@ int __weak alloc_bootmem_huge_page(struc
 				NODE_DATA(h->next_nid_to_alloc),
 				huge_page_size(h), huge_page_size(h), 0);
 
+		hstate_next_node_to_alloc(h);
 		if (addr) {
 			/*
 			 * Use the beginning of the huge page to store the
@@ -1039,7 +1040,6 @@ int __weak alloc_bootmem_huge_page(struc
 			m = addr;
 			goto found;
 		}
-		hstate_next_node_to_alloc(h);
 		nr_nodes--;
 	}
 	return 0;


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