+ mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration.patch added to -mm tree

+ mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm: hugetlb: soft-offline: dissolve source hugepage after successful migration
has been added to the -mm tree.  Its filename is
     mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration.patch

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------------------------------------------------------
From: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Subject: mm: hugetlb: soft-offline: dissolve source hugepage after successful migration

Currently hugepage migrated by soft-offline (i.e.  due to correctable
memory errors) is contained as a hugepage, which means many non-error
pages in it are unreusable, i.e.  wasted.

This patch solves this issue by dissolving source hugepages into buddy. 
As done in previous patch, PageHWPoison is set only on a head page of the
error hugepage.  Then in dissoliving we move the PageHWPoison flag to the
raw error page so that all healthy subpages return back to buddy.

Link: http://lkml.kernel.org/r/1496305019-5493-5-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/hugetlb.h |    2 ++
 mm/hugetlb.c            |   10 +++++++++-
 mm/memory-failure.c     |    5 +----
 mm/migrate.c            |    2 ++
 4 files changed, 14 insertions(+), 5 deletions(-)

diff -puN include/linux/hugetlb.h~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration include/linux/hugetlb.h
--- a/include/linux/hugetlb.h~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration
+++ a/include/linux/hugetlb.h
@@ -472,6 +472,7 @@ static inline pgoff_t basepage_index(str
 	return __basepage_index(page);
 }
 
+extern int dissolve_free_huge_page(struct page *page);
 extern int dissolve_free_huge_pages(unsigned long start_pfn,
 				    unsigned long end_pfn);
 static inline bool hugepage_migration_supported(struct hstate *h)
@@ -557,6 +558,7 @@ static inline pgoff_t basepage_index(str
 {
 	return page->index;
 }
+#define dissolve_free_huge_page(p)	0
 #define dissolve_free_huge_pages(s, e)	0
 #define hugepage_migration_supported(h)	false
 
diff -puN mm/hugetlb.c~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration mm/hugetlb.c
--- a/mm/hugetlb.c~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration
+++ a/mm/hugetlb.c
@@ -1459,7 +1459,7 @@ static int free_pool_huge_page(struct hs
  * number of free hugepages would be reduced below the number of reserved
  * hugepages.
  */
-static int dissolve_free_huge_page(struct page *page)
+int dissolve_free_huge_page(struct page *page)
 {
 	int rc = 0;
 
@@ -1472,6 +1472,14 @@ static int dissolve_free_huge_page(struc
 			rc = -EBUSY;
 			goto out;
 		}
+		/*
+		 * Move PageHWPoison flag from head page to the raw error page,
+		 * which makes any subpages rather than the error page reusable.
+		 */
+		if (PageHWPoison(head) && page != head) {
+			SetPageHWPoison(page);
+			ClearPageHWPoison(head);
+		}
 		list_del(&head->lru);
 		h->free_huge_pages--;
 		h->free_huge_pages_node[nid]--;
diff -puN mm/memory-failure.c~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration mm/memory-failure.c
--- a/mm/memory-failure.c~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration
+++ a/mm/memory-failure.c
@@ -1572,11 +1572,8 @@ static int soft_offline_huge_page(struct
 		if (ret > 0)
 			ret = -EIO;
 	} else {
-		/* overcommit hugetlb page will be freed to buddy */
-		SetPageHWPoison(page);
 		if (PageHuge(page))
-			dequeue_hwpoisoned_huge_page(hpage);
-		num_poisoned_pages_inc();
+			dissolve_free_huge_page(page);
 	}
 	return ret;
 }
diff -puN mm/migrate.c~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration mm/migrate.c
--- a/mm/migrate.c~mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration
+++ a/mm/migrate.c
@@ -1252,6 +1252,8 @@ put_anon:
 out:
 	if (rc != -EAGAIN)
 		putback_active_hugepage(hpage);
+	if (reason == MR_MEMORY_FAILURE && !test_set_page_hwpoison(hpage))
+		num_poisoned_pages_inc();
 
 	/*
 	 * If migration was not successful and there's a freeing callback, use
_

Patches currently in -mm which might be from khandual@linux.vnet.ibm.com are

mm-vmstat-standardize-file-operations-variable-names.patch
mm-madvise-enable-softhard-offline-of-hugetlb-pages-at-pgd-level.patch
mm-follow_page_mask-add-support-for-hugetlb-pgd-entries.patch
mm-hugetlb-soft-offline-dissolve-source-hugepage-after-successful-migration.patch