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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3C94C25B06 for ; Mon, 15 Aug 2022 01:59:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229990AbiHOB7H (ORCPT ); Sun, 14 Aug 2022 21:59:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37000 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229612AbiHOB67 (ORCPT ); Sun, 14 Aug 2022 21:58:59 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 52CEB12AB3 for ; Sun, 14 Aug 2022 18:58:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1660528738; x=1692064738; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=SnO+KuyY2Ig6pp+7jgz3mFNr913uLAxnryQVGv4z4qw=; b=hCyKHYXYhw/Nc9/CtPAHJlapN9nORTQ2LxFWoE9suBqJBwkY79N5EyWj SKye5swHEgYPUqQlUI8vkUA8Jypx0lFKdk/pqyQerAHDSN1uQY+h2q0WX yoEwZYTliRAy/HK0syn7JAsDeljz4I4GAd0O59ocV1f7GfB5dKXnyN3j0 +NKMO2kNBrJKpHioBEva5+XLU3evsr7H5HAsHR0MfK9Kch/xtoxfwg+YE C/42LTvgiJbu+QL02eAEcYAZBry/JTT3CSfn9aU6gL/GNVn4ekgdL9HME GbXxAfaix/Cn2hQu3Nhh5ZOtfc0ArElDiKVlPPZfUc33XbiW6N0HToZjL g==; X-IronPort-AV: E=McAfee;i="6400,9594,10439"; a="292667571" X-IronPort-AV: E=Sophos;i="5.93,237,1654585200"; d="scan'208";a="292667571" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Aug 2022 18:58:57 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,237,1654585200"; d="scan'208";a="557132019" Received: from sse-cse-haiyue-nuc.sh.intel.com ([10.239.241.114]) by orsmga003.jf.intel.com with ESMTP; 14 Aug 2022 18:58:55 -0700 From: Haiyue Wang To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, david@redhat.com, linmiaohe@huawei.com, ying.huang@intel.com, songmuchun@bytedance.com, naoya.horiguchi@linux.dev, alex.sierra@amd.com, Haiyue Wang Subject: [PATCH v4 1/2] mm: migration: fix the FOLL_GET failure on following huge page Date: Mon, 15 Aug 2022 09:59:08 +0800 Message-Id: <20220815015909.439623-2-haiyue.wang@intel.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815015909.439623-1-haiyue.wang@intel.com> References: <20220812084921.409142-1-haiyue.wang@intel.com> <20220815015909.439623-1-haiyue.wang@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Not all huge page APIs support FOLL_GET option, so the __NR_move_pages will fail to get the page node information for huge page. This is an temporary solution to mitigate the racing fix. 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 --- 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; } -- 2.37.2