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 c5b52c6e41f2 ("mm,
memory_hotplug: do not fail offlining too early").

Link: http://lkml.kernel.org/r/20180824063314.21981-1-aneesh.kumar@linux.ibm.com
Fixes: c5b52c6e41f2 ("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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9eea6e809a4e99fcf11125d47f28d7493af8b0ab..38d94b703e9d4932279b5657a2c889dfaaf1b749 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1333,7 +1333,8 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
                        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,

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 05e983f42316a1c5446536fb16cdf3f0ceb3cdd0..89d2a2ab3fe68c3ae46104074c519c7500dd86cb 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -7708,6 +7708,10 @@ bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
                 * 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;
                }