+ mm-hugetlb-filter-out-hugetlb-pages-if-hugepage-migration-is-not-supported.patch added to -mm tree

+ mm-hugetlb-filter-out-hugetlb-pages-if-hugepage-migration-is-not-supported.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm/hugetlb: filter out hugetlb pages if HUGEPAGE migration is not supported.
has been added to the -mm tree.  Its filename is
     mm-hugetlb-filter-out-hugetlb-pages-if-hugepage-migration-is-not-supported.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-filter-out-hugetlb-pages-if-hugepage-migration-is-not-supported.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-filter-out-hugetlb-pages-if-hugepage-migration-is-not-supported.patch

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------------------------------------------------------
From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Subject: mm/hugetlb: filter out hugetlb pages if HUGEPAGE migration is not supported.

When scanning for movable pages, filter out Hugetlb pages if hugepage
migration is not supported.  Without this we hit infinte loop in
__offline_pages() where we do

	pfn = scan_movable_pages(start_pfn, end_pfn);
	if (pfn) { /* We have movable pages */
		ret = do_migrate_range(pfn, end_pfn);
		goto repeat;
	}

Fix this by checking hugepage_migration_supported both in
has_unmovable_pages which is the primary backoff mechanism for page
offlining and for consistency reasons also into scan_movable_pages because
it doesn't make any sense to return a pfn to non-migrateable huge page.

This issue was revealed by, but not caused by 72b39cfc4d75 ("mm,
memory_hotplug: do not fail offlining too early").

Link: http://lkml.kernel.org/r/20180824063314.21981-1-aneesh.kumar@linux.ibm.com
Fixes: 72b39cfc4d75 ("mm, memory_hotplug: do not fail offlining too early")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reported-by: Haren Myneni <haren@linux.vnet.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/memory_hotplug.c |    3 ++-
 mm/page_alloc.c     |    4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

--- a/mm/memory_hotplug.c~mm-hugetlb-filter-out-hugetlb-pages-if-hugepage-migration-is-not-supported
+++ a/mm/memory_hotplug.c
@@ -1333,7 +1333,8 @@ static unsigned long scan_movable_pages(
 			if (__PageMovable(page))
 				return pfn;
 			if (PageHuge(page)) {
-				if (page_huge_active(page))
+				if (hugepage_migration_supported(page_hstate(page)) &&
+				    page_huge_active(page))
 					return pfn;
 				else
 					pfn = round_up(pfn + 1,
--- a/mm/page_alloc.c~mm-hugetlb-filter-out-hugetlb-pages-if-hugepage-migration-is-not-supported
+++ a/mm/page_alloc.c
@@ -7709,6 +7709,10 @@ bool has_unmovable_pages(struct zone *zo
 		 * handle each tail page individually in migration.
 		 */
 		if (PageHuge(page)) {
+
+			if (!hugepage_migration_supported(page_hstate(page)))
+				goto unmovable;
+
 			iter = round_up(iter + 1, 1<<compound_order(page)) - 1;
 			continue;
 		}
_

Patches currently in -mm which might be from aneesh.kumar@linux.ibm.com are

mm-hugetlb-filter-out-hugetlb-pages-if-hugepage-migration-is-not-supported.patch