[PATCH v2 5/5] mm/memory-failure: set PageHWPoison before migrate_pages()

[Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>]

Now page freeing code doesn't consider PageHWPoison as a bad page, so by
setting it before completing the page containment, we can prevent the error
page from being reused just after successful page migration.

I added TTU_IGNORE_HWPOISON for try_to_unmap() to make sure that the page
table entry is transformed into migration entry, not to hwpoison entry.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 mm/memory-failure.c | 7 ++++---
 mm/migrate.c        | 3 ++-
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git v4.2-rc4.orig/mm/memory-failure.c v4.2-rc4/mm/memory-failure.c
index cd985530f102..ea5a93659488 100644
--- v4.2-rc4.orig/mm/memory-failure.c
+++ v4.2-rc4/mm/memory-failure.c
@@ -1659,6 +1659,8 @@ static int __soft_offline_page(struct page *page, int flags)
 		inc_zone_page_state(page, NR_ISOLATED_ANON +
 					page_is_file_cache(page));
 		list_add(&page->lru, &pagelist);
+		if (!TestSetPageHWPoison(page))
+			atomic_long_inc(&num_poisoned_pages);
 		ret = migrate_pages(&pagelist, new_page, NULL, MPOL_MF_MOVE_ALL,
 					MIGRATE_SYNC, MR_MEMORY_FAILURE);
 		if (ret) {
@@ -1673,9 +1675,8 @@ static int __soft_offline_page(struct page *page, int flags)
 				pfn, ret, page->flags);
 			if (ret > 0)
 				ret = -EIO;
-		} else {
-			if (!TestSetPageHWPoison(page))
-				atomic_long_inc(&num_poisoned_pages);
+			if (TestClearPageHWPoison(page))
+				atomic_long_dec(&num_poisoned_pages);
 		}
 	} else {
 		pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n",
diff --git v4.2-rc4.orig/mm/migrate.c v4.2-rc4/mm/migrate.c
index f2415be7d93b..eb4267107d1f 100644
--- v4.2-rc4.orig/mm/migrate.c
+++ v4.2-rc4/mm/migrate.c
@@ -880,7 +880,8 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
 	/* Establish migration ptes or remove ptes */
 	if (page_mapped(page)) {
 		try_to_unmap(page,
-			TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
+			TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS|
+			TTU_IGNORE_HWPOISON);
 		page_was_mapped = 1;
 	}
 
-- 
2.4.3

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