[PATCH mmotm] mm: alloc_large_system_hash check order

[Hugh Dickins <hugh@veritas.com>]

On an x86_64 with 4GB ram, tcp_init()'s call to alloc_large_system_hash(),
to allocate tcp_hashinfo.ehash, is now triggering an mmotm WARN_ON_ONCE on
order >= MAX_ORDER - it's hoping for order 11.  alloc_large_system_hash()
had better make its own check on the order.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
---
Should probably follow
page-allocator-do-not-sanity-check-order-in-the-fast-path-fix.patch

Cc'ed DaveM and netdev, just in case they're surprised it was asking for
so much, or disappointed it's not getting as much as it was asking for.

 mm/page_alloc.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- 2.6.30-rc3-mm1/mm/page_alloc.c	2009-04-29 21:01:08.000000000 +0100
+++ mmotm/mm/page_alloc.c	2009-04-29 21:12:04.000000000 +0100
@@ -4765,7 +4765,10 @@ void *__init alloc_large_system_hash(con
 			table = __vmalloc(size, GFP_ATOMIC, PAGE_KERNEL);
 		else {
 			unsigned long order = get_order(size);
-			table = (void*) __get_free_pages(GFP_ATOMIC, order);
+
+			if (order < MAX_ORDER)
+				table = (void *)__get_free_pages(GFP_ATOMIC,
+								order);
 			/*
 			 * If bucketsize is not a power-of-two, we may free
 			 * some pages at the end of hash table.

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