xen/balloon: Avoid OOM when requesting highmem
If highmem pages are requested from the balloon on a system without
highmem, the implementation of alloc_xenballooned_pages will allocate
all available memory trying to find highmem pages to return. Allow
low memory to be returned when highmem pages are requested to avoid
this loop.
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index a767884..31ab82f 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -501,7 +501,7 @@
* alloc_xenballooned_pages - get pages that have been ballooned out
* @nr_pages: Number of pages to get
* @pages: pages returned
- * @highmem: highmem or lowmem pages
+ * @highmem: allow highmem pages
* @return 0 on success, error otherwise
*/
int alloc_xenballooned_pages(int nr_pages, struct page **pages, bool highmem)
@@ -511,7 +511,7 @@
mutex_lock(&balloon_mutex);
while (pgno < nr_pages) {
page = balloon_retrieve(highmem);
- if (page && PageHighMem(page) == highmem) {
+ if (page && (highmem || !PageHighMem(page))) {
pages[pgno++] = page;
} else {
enum bp_state st;