From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by kanga.kvack.org (Postfix) with ESMTP id 989966B0038 for ; Tue, 12 Sep 2017 16:43:39 -0400 (EDT) Received: by mail-wr0-f198.google.com with SMTP id v109so12950206wrc.5 for ; Tue, 12 Sep 2017 13:43:39 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id o44sor4569138wrf.86.2017.09.12.13.43.38 for (Google Transport Security); Tue, 12 Sep 2017 13:43:38 -0700 (PDT) Date: Tue, 12 Sep 2017 22:43:06 +0200 From: Alexandru Moise <00moses.alexander00@gmail.com> Subject: [PATCH] mm, hugetlb, soft_offline: save compound page order before page migration Message-ID: <20170912204306.GA12053@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org, khandual@linux.vnet.ibm.com, akpm@linux-foundation.org, mhocko@suse.com, aarcange@redhat.com, minchan@kernel.org, hillf.zj@alibaba-inc.com, shli@fb.com, rppt@linux.vnet.ibm.com, kirill.shutemov@linux.intel.com, mgorman@techsingularity.net, rientjes@google.com, riel@redhat.com, linux-mm@kvack.org This fixes a bug in madvise() where if you'd try to soft offline a hugepage via madvise(), while walking the address range you'd end up, using the wrong page offset due to attempting to get the compound order of a former but presently not compound page, due to dissolving the huge page (since c3114a8). Signed-off-by: Alexandru Moise <00moses.alexander00@gmail.com> --- mm/madvise.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/mm/madvise.c b/mm/madvise.c index 21261ff0466f..25bade36e9ca 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -625,18 +625,26 @@ static int madvise_inject_error(int behavior, { struct page *page; struct zone *zone; + unsigned int order; if (!capable(CAP_SYS_ADMIN)) return -EPERM; - for (; start < end; start += PAGE_SIZE << - compound_order(compound_head(page))) { + + for (; start < end; start += PAGE_SIZE << order) { int ret; ret = get_user_pages_fast(start, 1, 0, &page); if (ret != 1) return ret; + /* + * When soft offlining hugepages, after migrating the page + * we dissolve it, therefore in the second loop "page" will + * no longer be a compound page, and order will be 0. + */ + order = compound_order(compound_head(page)); + if (PageHWPoison(page)) { put_page(page); continue; -- 2.14.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org