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SubjectRe: [PATCH 2/9] hugetlb: add allocate function for hugepage migration
Hi,

On Mon, Aug 16, 2010 at 11:51:30PM -0700, David Rientjes wrote:
> On Tue, 10 Aug 2010, Naoya Horiguchi wrote:
...
> > +/*
> > + * This allocation function is useful in the context where vma is irrelevant.
> > + * E.g. soft-offlining uses this function because it only cares physical
> > + * address of error page.
> > + */
> > +struct page *alloc_huge_page_no_vma_node(struct hstate *h, int nid)
> > +{
> > + struct page *page;
> > +
> > + spin_lock(&hugetlb_lock);
> > + get_mems_allowed();
>
> Why is this calling get_mems_allowed()? dequeue_huge_page_node() isn't
> concerned if nid can be allocated by current in this context.

OK, I'll remove this.

> > + page = dequeue_huge_page_node(h, nid);
> > + put_mems_allowed();
> > + spin_unlock(&hugetlb_lock);
> > +
> > + if (!page) {
> > + page = alloc_buddy_huge_page_node(h, nid);
> > + if (!page) {
> > + __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
> > return NULL;
> > - }
> > - prep_new_huge_page(h, page, nid);
> > + } else
> > + __count_vm_event(HTLB_BUDDY_PGALLOC);
> > }
> >
> > + set_page_refcounted(page);
>
> Possibility of NULL pointer dereference?

I think this allocate function returns without calling
set_page_refcounted() if page == NULL. Or do you mean another point?

Thanks,
Naoya Horiguchi


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