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 @@ -7708,6 +7708,10 @@ 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; } _