From: Joe Jin Date: Mon, 16 Jul 2007 06:38:12 +0000 (-0700) Subject: hugetlb: fix race in alloc_fresh_huge_page() X-Git-Tag: v2.6.23-rc1~1028 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f96efd585b8d847181f81bf16721f96ded18d9fe;p=linux-2.6 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 Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/hugetlb.c b/mm/hugetlb.c index eaba7d6b25..acc0fb3cf0 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);