Re: [PATCH] Add nid sanity on alloc_pages_node

[gurudas pai]

Andrew Morton wrote:
> On Fri, 13 Jul 2007 14:40:04 +0800 Joe Jin <joe.jin@xxxxxxxxxx> wrote:
>
> > On 2007-07-12 22:18, Andrew Morton wrote:
> > > On Fri, 13 Jul 2007 10:45:07 +0800 Joe Jin <joe.jin@xxxxxxxxxx> 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


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