[PATCH 08/10] HWPOISON, hugetlb: soft offlining for hugepage

[Naoya Horiguchi]

This patch extends soft offlining framework to support hugepage.
When memory corrected errors occur repeatedly on a hugepage,
we can choose to stop using it by migrating data onto another hugepage
and disabling the original (maybe half-broken) one.

ChangeLog since v3:
- remove comment about "ToDo: hugepage soft-offline"

ChangeLog since v2:
- move refcount handling into isolate_lru_page()

ChangeLog since v1:
- add double check in isolating hwpoisoned hugepage
- define free/non-free checker for hugepage
- postpone calling put_page() for hugepage in soft_offline_page()

Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Signed-off-by: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx>
---
 mm/memory-failure.c |   50 +++++++++++++++++++++++++++++++++-----------------
 1 files changed, 33 insertions(+), 17 deletions(-)

diff --git v2.6.36-rc2/mm/memory-failure.c v2.6.36-rc2/mm/memory-failure.c
index dfeb8b8..80e71cd 100644
--- v2.6.36-rc2/mm/memory-failure.c
+++ v2.6.36-rc2/mm/memory-failure.c
@@ -693,8 +693,6 @@ static int me_swapcache_clean(struct page *p, unsigned long pfn)
  * Issues:
  * - Error on hugepage is contained in hugepage unit (not in raw page unit.)
  *   To narrow down kill region to one page, we need to break up pmd.
- * - To support soft-offlining for hugepage, we need to support hugepage
- *   migration.
  */
 static int me_huge_page(struct page *p, unsigned long pfn)
 {
@@ -1220,7 +1218,11 @@ EXPORT_SYMBOL(unpoison_memory);
 static struct page *new_page(struct page *p, unsigned long private, int **x)
 {
 	int nid = page_to_nid(p);
-	return alloc_pages_exact_node(nid, GFP_HIGHUSER_MOVABLE, 0);
+	if (PageHuge(p))
+		return alloc_huge_page_node(page_hstate(compound_head(p)),
+						   nid);
+	else
+		return alloc_pages_exact_node(nid, GFP_HIGHUSER_MOVABLE, 0);
 }
 
 /*
@@ -1248,8 +1250,15 @@ static int get_any_page(struct page *p, unsigned long pfn, int flags)
 	 * was free.
 	 */
 	set_migratetype_isolate(p);
+	/*
+	 * When the target page is a free hugepage, just remove it
+	 * from free hugepage list.
+	 */
 	if (!get_page_unless_zero(compound_head(p))) {
-		if (is_free_buddy_page(p)) {
+		if (PageHuge(p)) {
+			pr_debug("get_any_page: %#lx free huge page\n", pfn);
+			ret = dequeue_hwpoisoned_huge_page(compound_head(p));
+		} else if (is_free_buddy_page(p)) {
 			pr_debug("get_any_page: %#lx free buddy page\n", pfn);
 			/* Set hwpoison bit while page is still isolated */
 			SetPageHWPoison(p);
@@ -1294,6 +1303,7 @@ int soft_offline_page(struct page *page, int flags)
 {
 	int ret;
 	unsigned long pfn = page_to_pfn(page);
+	struct page *hpage = compound_head(page);
 
 	ret = get_any_page(page, pfn, flags);
 	if (ret < 0)
@@ -1304,7 +1314,7 @@ int soft_offline_page(struct page *page, int flags)
 	/*
 	 * Page cache page we can handle?
 	 */
-	if (!PageLRU(page)) {
+	if (!PageLRU(page) && !PageHuge(page)) {
 		/*
 		 * Try to free it.
 		 */
@@ -1320,21 +1330,21 @@ int soft_offline_page(struct page *page, int flags)
 		if (ret == 0)
 			goto done;
 	}
-	if (!PageLRU(page)) {
+	if (!PageLRU(page) && !PageHuge(page)) {
 		pr_debug("soft_offline: %#lx: unknown non LRU page type %lx\n",
 				pfn, page->flags);
 		return -EIO;
 	}
 
-	lock_page(page);
-	wait_on_page_writeback(page);
+	lock_page(hpage);
+	wait_on_page_writeback(hpage);
 
 	/*
 	 * Synchronized using the page lock with memory_failure()
 	 */
-	if (PageHWPoison(page)) {
-		unlock_page(page);
-		put_page(page);
+	if (PageHWPoison(hpage)) {
+		unlock_page(hpage);
+		put_page(hpage);
 		pr_debug("soft offline: %#lx page already poisoned\n", pfn);
 		return -EBUSY;
 	}
@@ -1344,7 +1354,7 @@ int soft_offline_page(struct page *page, int flags)
 	 * non dirty unmapped page cache pages.
 	 */
 	ret = invalidate_inode_page(page);
-	unlock_page(page);
+	unlock_page(hpage);
 
 	/*
 	 * Drop count because page migration doesn't like raised
@@ -1353,7 +1363,7 @@ int soft_offline_page(struct page *page, int flags)
 	 * RED-PEN would be better to keep it isolated here, but we
 	 * would need to fix isolation locking first.
 	 */
-	put_page(page);
+	put_page(hpage);
 	if (ret == 1) {
 		ret = 0;
 		pr_debug("soft_offline: %#lx: invalidated\n", pfn);
@@ -1369,7 +1379,7 @@ int soft_offline_page(struct page *page, int flags)
 	if (!ret) {
 		LIST_HEAD(pagelist);
 
-		list_add(&page->lru, &pagelist);
+		list_add(&hpage->lru, &pagelist);
 		ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0);
 		if (ret) {
 			pr_debug("soft offline: %#lx: migration failed %d, type %lx\n",
@@ -1385,9 +1395,15 @@ int soft_offline_page(struct page *page, int flags)
 		return ret;
 
 done:
-	atomic_long_add(1, &mce_bad_pages);
-	SetPageHWPoison(page);
-	/* keep elevated page count for bad page */
+	if (!PageHWPoison(hpage))
+		atomic_long_add(1 << compound_order(hpage), &mce_bad_pages);
+	if (PageHuge(hpage)) {
+		set_page_hwpoison_huge_page(hpage);
+		dequeue_hwpoisoned_huge_page(hpage);
+	} else {
+		SetPageHWPoison(page);
+		/* keep elevated page count for bad page */
+	}
 	return ret;
 }
 
-- 
1.7.2.2

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