[PATCH 2/2] xen/page_alloc: Defer the domain mapping in scrub_one_page()

[Andrew Cooper <andrew.cooper3@citrix.com>]

This avoids a resource leak and needless playing with the pagetables in the
case that the page is broken.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Keir Fraser <keir@xen.org>
CC: Jan Beulich <JBeulich@suse.com>
CC: Tim Deegan <tim@xen.org>
---
 xen/common/page_alloc.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 8002bd2..5f484a2 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -1652,11 +1652,13 @@ __initcall(pagealloc_keyhandler_init);
 
 void scrub_one_page(struct page_info *pg)
 {
-    void *p = __map_domain_page(pg);
+    void *p;
 
     if ( unlikely(pg->count_info & PGC_broken) )
         return;
 
+    p = __map_domain_page(pg);
+
 #ifndef NDEBUG
     /* Avoid callers relying on allocations returning zeroed pages. */
     memset(p, 0xc2, PAGE_SIZE);
-- 
1.7.10.4