hugetlb: call arch_prepare_hugepage() for surplus pages

The s390 software large page emulation implements shared page tables by
using page->index of the first tail page from a compound large page to
store page table information.  This is set up in arch_prepare_hugepage(),
which is called from alloc_fresh_huge_page_node().

A similar call to arch_prepare_hugepage() is missing for surplus large
pages that are allocated in alloc_buddy_huge_page(), which breaks the
software emulation mode for (surplus) large pages on s390.  This patch
adds the missing call to arch_prepare_hugepage().  It will have no effect
on other architectures where arch_prepare_hugepage() is a nop.

Also, use the correct order in the error path in alloc_fresh_huge_page_node().

Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Acked-by: Adam Litke <agl@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 757ca983fd99..92155db888b9 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -565,7 +565,7 @@ static struct page *alloc_fresh_huge_page_node(struct hstate *h, int nid)
                 huge_page_order(h));
         if (page) {
                 if (arch_prepare_hugepage(page)) {
-                        __free_pages(page, HUGETLB_PAGE_ORDER);
+                        __free_pages(page, huge_page_order(h));
                         return NULL;
                 }
                 prep_new_huge_page(h, page, nid);
@@ -665,6 +665,11 @@ static struct page *alloc_buddy_huge_page(struct hstate *h,
                                         __GFP_REPEAT|__GFP_NOWARN,
                                         huge_page_order(h));
 
+        if (page && arch_prepare_hugepage(page)) {
+                __free_pages(page, huge_page_order(h));
+                return NULL;
+        }
+
         spin_lock(&hugetlb_lock);
         if (page) {
                 /*