4.18-stable review patch. If anyone has any objections, please let me know.
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From: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com
commit 464c7ffbcb164b2e5cebfa406b7fc6cdb7945344 upstream.
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 Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- mm/memory_hotplug.c | 3 ++- mm/page_alloc.c | 4 ++++ 2 files changed, 6 insertions(+), 1 deletion(-)
--- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1341,7 +1341,8 @@ 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 +++ b/mm/page_alloc.c @@ -7649,6 +7649,10 @@ 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; }