[PATCH RFC 5/6] hv_balloon: mark inflated pages PG_offline

David Hildenbrand
2018-11-14T21:17:03Z

Mark inflated and never onlined pages PG_offline, to tell the world that
the content is stale and should not be dumped.

Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Kairui Song <kasong@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
drivers/hv/hv_balloon.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/hv/hv_balloon.c b/drivers/hv/hv_balloon.c
index 5728dc470eeb..778b6f879d1c 100644
--- a/drivers/hv/hv_balloon.c
+++ b/drivers/hv/hv_balloon.c
@@ -681,8 +681,13 @@ static struct notifier_block hv_memory_nb = {
/* Check if the particular page is backed and can be onlined and online it. */
static void hv_page_online_one(struct hv_hotadd_state *has, struct page *pg)
{
- if (!has_pfn_is_backed(has, page_to_pfn(pg)))
+ if (!has_pfn_is_backed(has, page_to_pfn(pg))) {
+ if (!PageOffline(pg))
+ __SetPageOffline(pg);
return;
+ }
+ if (PageOffline(pg))
+ __ClearPageOffline(pg);

/* This frame is currently backed; online the page. */
__online_page_set_limits(pg);
@@ -1200,6 +1205,7 @@ static void free_balloon_pages(struct hv_dynmem_device *dm,

for (i = 0; i < num_pages; i++) {
pg = pfn_to_page(i + start_frame);
+ __ClearPageOffline(pg);
__free_page(pg);
dm->num_pages_ballooned--;
}
@@ -1212,7 +1218,7 @@ static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm,
struct dm_balloon_response *bl_resp,
int alloc_unit)
{
- unsigned int i = 0;
+ unsigned int i, j;
struct page *pg;

if (num_pages < alloc_unit)
@@ -1244,6 +1250,10 @@ static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm,
if (alloc_unit != 1)
split_page(pg, get_order(alloc_unit << PAGE_SHIFT));

+ /* mark all pages offline */
+ for (j = 0; j < (1 << get_order(alloc_unit << PAGE_SHIFT)); j++)
+ __SetPageOffline(pg + j);
+
bl_resp->range_count++;
bl_resp->range_array[i].finfo.start_page =
page_to_pfn(pg);
--
2.17.2