On Jun 28, 2011, at 4:39 PM, Benjamin Herrenschmidt wrote:

On Tue, 2011-06-28 at 14:54 -0500, Becky Bruce wrote:

quoted

struct page *alloc_huge_page_node(struct hstate *h, int nid);

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 6402458..2db81ea 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c

@@ -1105,8 +1105,14 @@ static void __init

gather_bootmem_prealloc(void)
       struct huge_bootmem_page *m;
=20
       list_for_each_entry(m, &huge_boot_pages, list) {
-               struct page *page =3D virt_to_page(m);
               struct hstate *h =3D m->hstate;
+#ifdef CONFIG_HIGHMEM
+               struct page *page =3D pfn_to_page(m->phys >>
PAGE_SHIFT);
+               free_bootmem_late((unsigned long)m,
+                                 sizeof(struct huge_bootmem_page));
+#else
+               struct page *page =3D virt_to_page(m);
+#endif
               __ClearPageReserved(page);

=20
Why do you add free_bootmem_late() in the highmem case and not the
normal case ?

Because there was no bootmem allocation in the normal case - the =
non-highmem version stores data structure in the huge page itself.  This =
is perfectly fine as long as you have a mapping.  Since this isn't true =
for HIGHMEM pages, I allocate bootmem to store the early data structure =
that stores information about the hugepage (this happens in =
arch-specific code in alloc_bootmem_huge_page).

-Becky