[PATCH 3/3] mm/memory_hotplug: make HWPoisoned dirty swapcache pages unmovable

[Miaohe Lin]

HWPoisoned dirty swapcache pages are kept for killing owner processes.
We should not offline these pages or do_swap_page() would access the
offline pages and lead to bad ending.

Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
 mm/memory_hotplug.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9fd0be32a281..0488eed3327c 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1664,6 +1664,12 @@ static int scan_movable_pages(unsigned long start, unsigned long end,
 		 */
 		if (PageOffline(page) && page_count(page))
 			return -EBUSY;
+		/*
+		 * HWPoisoned dirty swapcache pages are definitely unmovable
+		 * because they are kept for killing owner processes.
+		 */
+		if (PageHWPoison(page) && PageSwapCache(page))
+			return -EBUSY;
 
 		if (!PageHuge(page))
 			continue;
-- 
2.23.0