From: Joe Jin <joe.jin@oracle.com>
Date: Mon, 16 Jul 2007 06:38:12 +0000 (-0700)
Subject: hugetlb: fix race in alloc_fresh_huge_page()
X-Git-Tag: upstream/snapshot3+hdmi~32912
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=f96efd585b8d847181f81bf16721f96ded18d9fe;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

hugetlb: fix race in alloc_fresh_huge_page()

That static `nid' index needs locking.  Without it we can end up calling
alloc_pages_node() with an illegal node ID and the kernel crashes.

Acked-by: gurudas pai <gurudas.pai@oracle.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index eaba7d6..acc0fb3 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -101,13 +101,20 @@ static void free_huge_page(struct page *page)
 
 static int alloc_fresh_huge_page(void)
 {
-	static int nid = 0;
+	static int prev_nid;
 	struct page *page;
-	page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP|__GFP_NOWARN,
-					HUGETLB_PAGE_ORDER);
-	nid = next_node(nid, node_online_map);
+	static DEFINE_SPINLOCK(nid_lock);
+	int nid;
+
+	spin_lock(&nid_lock);
+	nid = next_node(prev_nid, node_online_map);
 	if (nid == MAX_NUMNODES)
 		nid = first_node(node_online_map);
+	prev_nid = nid;
+	spin_unlock(&nid_lock);
+
+	page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP|__GFP_NOWARN,
+					HUGETLB_PAGE_ORDER);
 	if (page) {
 		set_compound_page_dtor(page, free_huge_page);
 		spin_lock(&hugetlb_lock);