Re: [PATCH] Add nid sanity on alloc_pages_node

[gurudas pai <gurudas.pai@oracle.com>]

Andrew Morton wrote:
> On Fri, 13 Jul 2007 14:40:04 +0800 Joe Jin <joe.jin@oracle.com> wrote:
>
>> On 2007-07-12 22:18, Andrew Morton wrote:
>>> On Fri, 13 Jul 2007 10:45:07 +0800 Joe Jin <joe.jin@oracle.com> wrote:
>>>
>>> Something like this?
>>>
>>> --- a/mm/hugetlb.c~a
>>> +++ a/mm/hugetlb.c
>>> @@ -105,13 +105,20 @@ static void free_huge_page(struct page *
>>>  
>>>  static int alloc_fresh_huge_page(void)
>>>  {
>>> -	static int nid = 0;
>>> +	static int prev_nid;
>>> +	static DEFINE_SPINLOCK(nid_lock);
>>>  	struct page *page;
>>> -	page = alloc_pages_node(nid, htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN,
>>> -					HUGETLB_PAGE_ORDER);
>>> -	nid = next_node(nid, node_online_map);
>>> +	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, htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN,
>>> +					HUGETLB_PAGE_ORDER);
>>>  	if (page) {
>>>  		set_compound_page_dtor(page, free_huge_page);
>>>  		spin_lock(&hugetlb_lock);
>>> _
>>>
I think this will never get pages from node 0 ? Because nid = 
next_node(prev_node,node_online_map) and even if prev_node = 0, nid will 
become 1.

How about this patch ?


--- linux-2.6.22.orig/mm/hugetlb.c 2007-07-08 16:32:17.000000000 -0700
+++ linux-2.6.22-devel/mm//hugetlb.c 2007-07-13 00:26:27.000000000 -0700
@@ -103,11 +103,18 @@
{
static int nid = 0;
struct page *page;
- page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP|__GFP_NOWARN,
- HUGETLB_PAGE_ORDER);
+ int cur_nid;
+ static DEFINE_SPINLOCK(nid_lock);
+
+ spin_lock(&nid_lock);
+ cur_nid = nid;
nid = next_node(nid, node_online_map);
if (nid == MAX_NUMNODES)
nid = first_node(node_online_map);
+ spin_unlock(&nid_lock);
+
+ page = alloc_pages_node(cur_nid, GFP_HIGHUSER|__GFP_COMP|__GFP_NOWARN,
+ HUGETLB_PAGE_ORDER);
if (page) {
set_compound_page_dtor(page, free_huge_page);
spin_lock(&hugetlb_lock);



Thanks,
-Guru