From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 40371C4321D for ; Fri, 24 Aug 2018 07:58:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EF5E62157F for ; Fri, 24 Aug 2018 07:58:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EF5E62157F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727871AbeHXLbq (ORCPT ); Fri, 24 Aug 2018 07:31:46 -0400 Received: from mx2.suse.de ([195.135.220.15]:54614 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726899AbeHXLbp (ORCPT ); Fri, 24 Aug 2018 07:31:45 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 13344ADF3; Fri, 24 Aug 2018 07:58:16 +0000 (UTC) Date: Fri, 24 Aug 2018 09:58:15 +0200 From: Michal Hocko To: "Aneesh Kumar K.V" Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, mike.kravetz@oracle.com, Naoya Horiguchi Subject: Re: [PATCH] mm/hugetlb: filter out hugetlb pages if HUGEPAGE migration is not supported. Message-ID: <20180824075815.GA29735@dhcp22.suse.cz> References: <20180824063314.21981-1-aneesh.kumar@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180824063314.21981-1-aneesh.kumar@linux.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 24-08-18 12:03:14, Aneesh Kumar K.V wrote: > 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; > } > > We do support hugetlb migration ony if the hugetlb pages are at pmd level. Here > we just check for Kernel config. The gigantic page size check is done in > page_huge_active. Well, this is a bit misleading. I would say that 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. > Acked-by: Michal Hocko > Reported-by: Haren Myneni > CC: Naoya Horiguchi > Signed-off-by: Aneesh Kumar K.V I would add Fixes: 72b39cfc4d75 ("mm, memory_hotplug: do not fail offlining too early") Not because the bug has been introduced by that commit but rather because the issue would be latent before that commit. My Acked-by still holds. > --- > mm/memory_hotplug.c | 3 ++- > mm/page_alloc.c | 4 ++++ > 2 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 9eea6e809a4e..38d94b703e9d 100644 > --- 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 c677c1506d73..b8d91f59b836 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -7709,6 +7709,10 @@ 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< continue; > } > -- > 2.17.1 -- Michal Hocko SUSE Labs