From patchwork Mon Aug 15 07:02:39 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Wang, Haiyue" X-Patchwork-Id: 12943177 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79F84C25B0E for ; Mon, 15 Aug 2022 07:02:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D995C6B0073; Mon, 15 Aug 2022 03:02:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D49388D0002; Mon, 15 Aug 2022 03:02:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BEA066B0075; Mon, 15 Aug 2022 03:02:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id B0AAD6B0073 for ; 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X-IronPort-AV: E=McAfee;i="6400,9594,10439"; a="271677579" X-IronPort-AV: E=Sophos;i="5.93,237,1654585200"; d="scan'208";a="271677579" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Aug 2022 00:02:31 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,237,1654585200"; d="scan'208";a="666566767" Received: from sse-cse-haiyue-nuc.sh.intel.com ([10.239.241.114]) by fmsmga008.fm.intel.com with ESMTP; 15 Aug 2022 00:02:27 -0700 From: Haiyue Wang To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, david@redhat.com, apopple@nvidia.com, linmiaohe@huawei.com, ying.huang@intel.com, songmuchun@bytedance.com, naoya.horiguchi@linux.dev, alex.sierra@amd.com, Haiyue Wang Subject: [PATCH v5 1/2] mm: migration: fix the FOLL_GET failure on following huge page Date: Mon, 15 Aug 2022 15:02:39 +0800 Message-Id: <20220815070240.470469-2-haiyue.wang@intel.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815070240.470469-1-haiyue.wang@intel.com> References: <20220812084921.409142-1-haiyue.wang@intel.com> <20220815070240.470469-1-haiyue.wang@intel.com> MIME-Version: 1.0 ARC-Authentication-Results: i=1; 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dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=dIrfVjlH; spf=pass (imf27.hostedemail.com: domain of haiyue.wang@intel.com designates 192.55.52.136 as permitted sender) smtp.mailfrom=haiyue.wang@intel.com; dmarc=pass (policy=none) header.from=intel.com X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: D6DA9401C1 X-Stat-Signature: x3eh6daninrp4gooj8pqccse1xsm9ui9 X-Rspam-User: X-HE-Tag: 1660546951-86914 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Not all huge page APIs support FOLL_GET option, so move_pages() syscall will fail to get the page node information for some huge pages. Like x86 on linux 5.19 with 1GB huge page API follow_huge_pud(), it will return NULL page for FOLL_GET when calling move_pages() syscall with the NULL 'nodes' parameter, the 'status' parameter has '-2' error in array. Note: follow_huge_pud() now supports FOLL_GET in linux 6.0. Link: https://lore.kernel.org/all/20220714042420.1847125-3-naoya.horiguchi@linux.dev But these huge page APIs don't support FOLL_GET: 1. follow_huge_pud() in arch/s390/mm/hugetlbpage.c 2. follow_huge_addr() in arch/ia64/mm/hugetlbpage.c It will cause WARN_ON_ONCE for FOLL_GET. 3. follow_huge_pgd() in mm/hugetlb.c This is an temporary solution to mitigate the side effect of the race condition fix by calling follow_page() with FOLL_GET set for huge pages. After supporting follow huge page by FOLL_GET is done, this fix can be reverted safely. Fixes: 4cd614841c06 ("mm: migration: fix possible do_pages_stat_array racing with memory offline") Signed-off-by: Haiyue Wang Reviewed-by: "Huang, Ying" --- mm/migrate.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/mm/migrate.c b/mm/migrate.c index 6a1597c92261..581dfaad9257 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1848,6 +1848,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, for (i = 0; i < nr_pages; i++) { unsigned long addr = (unsigned long)(*pages); + unsigned int foll_flags = FOLL_DUMP; struct vm_area_struct *vma; struct page *page; int err = -EFAULT; @@ -1856,8 +1857,12 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, if (!vma) goto set_status; + /* Not all huge page follow APIs support 'FOLL_GET' */ + if (!is_vm_hugetlb_page(vma)) + foll_flags |= FOLL_GET; + /* FOLL_DUMP to ignore special (like zero) pages */ - page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); + page = follow_page(vma, addr, foll_flags); err = PTR_ERR(page); if (IS_ERR(page)) @@ -1865,7 +1870,8 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, if (page && !is_zone_device_page(page)) { err = page_to_nid(page); - put_page(page); + if (foll_flags & FOLL_GET) + put_page(page); } else { err = -ENOENT; }