1 files changed, 52 insertions, 11 deletions

diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
index 4b5e939ff4c8..043eed845246 100644
--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -239,6 +239,7 @@ static DEFINE_STATIC_KEY_FALSE(balloon_stat_enabled);
 struct vmballoon_ctl {
 	struct list_head pages;
 	struct list_head refused_pages;
+	struct list_head prealloc_pages;
 	unsigned int n_refused_pages;
 	unsigned int n_pages;
 	enum vmballoon_page_size_type page_size;
@@ -668,15 +669,25 @@ static int vmballoon_alloc_page_list(struct vmballoon *b,
 	unsigned int i;
 
 	for (i = 0; i < req_n_pages; i++) {
-		if (ctl->page_size == VMW_BALLOON_2M_PAGE)
-			page = alloc_pages(__GFP_HIGHMEM|__GFP_NOWARN|
+		/*
+		 * First check if we happen to have pages that were allocated
+		 * before. This happens when 2MB page rejected during inflation
+		 * by the hypervisor, and then split into 4KB pages.
+		 */
+		if (!list_empty(&ctl->prealloc_pages)) {
+			page = list_first_entry(&ctl->prealloc_pages,
+						struct page, lru);
+			list_del(&page->lru);
+		} else {
+			if (ctl->page_size == VMW_BALLOON_2M_PAGE)
+				page = alloc_pages(__GFP_HIGHMEM|__GFP_NOWARN|
 					__GFP_NOMEMALLOC, VMW_BALLOON_2M_ORDER);
-		else
-			page = balloon_page_alloc();
+			else
+				page = balloon_page_alloc();
 
-		/* Update statistics */
-		vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC,
-					 ctl->page_size);
+			vmballoon_stats_page_inc(b, VMW_BALLOON_PAGE_STAT_ALLOC,
+						 ctl->page_size);
+		}
 
 		if (page) {
 			vmballoon_mark_page_offline(page, ctl->page_size);
@@ -922,7 +933,8 @@ static void vmballoon_release_page_list(struct list_head *page_list,
 		__free_pages(page, vmballoon_page_order(page_size));
 	}
 
-	*n_pages = 0;
+	if (n_pages)
+		*n_pages = 0;
 }
 
 
@@ -1055,6 +1067,32 @@ static void vmballoon_dequeue_page_list(struct vmballoon *b,
 }
 
 /**
+ * vmballoon_split_refused_pages() - Split the 2MB refused pages to 4k.
+ *
+ * If inflation of 2MB pages was denied by the hypervisor, it is likely to be
+ * due to one or few 4KB pages. These 2MB pages may keep being allocated and
+ * then being refused. To prevent this case, this function splits the refused
+ * pages into 4KB pages and adds them into @prealloc_pages list.
+ *
+ * @ctl: pointer for the %struct vmballoon_ctl, which defines the operation.
+ */
+static void vmballoon_split_refused_pages(struct vmballoon_ctl *ctl)
+{
+	struct page *page, *tmp;
+	unsigned int i, order;
+
+	order = vmballoon_page_order(ctl->page_size);
+
+	list_for_each_entry_safe(page, tmp, &ctl->refused_pages, lru) {
+		list_del(&page->lru);
+		split_page(page, order);
+		for (i = 0; i < (1 << order); i++)
+			list_add(&page[i].lru, &ctl->prealloc_pages);
+	}
+	ctl->n_refused_pages = 0;
+}
+
+/**
  * vmballoon_inflate() - Inflate the balloon towards its target size.
  *
  * @b: pointer to the balloon.
@@ -1065,6 +1103,7 @@ static void vmballoon_inflate(struct vmballoon *b)
 	struct vmballoon_ctl ctl = {
 		.pages = LIST_HEAD_INIT(ctl.pages),
 		.refused_pages = LIST_HEAD_INIT(ctl.refused_pages),
+		.prealloc_pages = LIST_HEAD_INIT(ctl.prealloc_pages),
 		.page_size = b->max_page_size,
 		.op = VMW_BALLOON_INFLATE
 	};
@@ -1112,10 +1151,10 @@ static void vmballoon_inflate(struct vmballoon *b)
 				break;
 
 			/*
-			 * Ignore errors from locking as we now switch to 4k
-			 * pages and we might get different errors.
+			 * Split the refused pages to 4k. This will also empty
+			 * the refused pages list.
 			 */
-			vmballoon_release_refused_pages(b, &ctl);
+			vmballoon_split_refused_pages(&ctl);
 			ctl.page_size--;
 		}
 
@@ -1129,6 +1168,8 @@ static void vmballoon_inflate(struct vmballoon *b)
 	 */
 	if (ctl.n_refused_pages != 0)
 		vmballoon_release_refused_pages(b, &ctl);
+
+	vmballoon_release_page_list(&ctl.prealloc_pages, NULL, ctl.page_size);
 }
 
 /**