xen/balloon: Move dec_totalhigh_pages() from __balloon_append() to balloon_append()

git commit 9be4d4575906af9698de660e477f949a076c87e1 (xen: add
extra pages to balloon) splited balloon_append() into two functions
(balloon_append() and __balloon_append()) and left decrementation
of totalram_pages counter in __balloon_append(). In this situation
if __balloon_append() is called on i386 with highmem page referenced
then totalhigh_pages is decremented, however, it should not. This
patch corrects that issue and moves dec_totalhigh_pages() from
__balloon_append() to balloon_append(). Now totalram_pages and
totalhigh_pages are decremented simultaneously only when
balloon_append() is called.

Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: Daniel Kiper <dkiper@net-space.pl>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index a6d8e59e453..f54290baa3d 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -114,7 +114,6 @@ static void __balloon_append(struct page *page)
         if (PageHighMem(page)) {
                 list_add_tail(&page->lru, &ballooned_pages);
                 balloon_stats.balloon_high++;
-                dec_totalhigh_pages();
         } else {
                 list_add(&page->lru, &ballooned_pages);
                 balloon_stats.balloon_low++;
@@ -124,6 +123,8 @@ static void __balloon_append(struct page *page)
 static void balloon_append(struct page *page)
 {
         __balloon_append(page);
+        if (PageHighMem(page))
+                dec_totalhigh_pages();
         totalram_pages--;
 }
 
@@ -462,7 +463,7 @@ static int __init balloon_init(void)
              pfn < extra_pfn_end;
              pfn++) {
                 page = pfn_to_page(pfn);
-                /* totalram_pages doesn't include the boot-time
+                /* totalram_pages and totalhigh_pages do not include the boot-time
                    balloon extension, so don't subtract from it. */
                 __balloon_append(page);
         }