From nobody Wed Apr 8 06:03:34 2026 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 6BA0CC32772 for ; Tue, 23 Aug 2022 17:13:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244107AbiHWRM7 (ORCPT ); Tue, 23 Aug 2022 13:12:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44238 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344912AbiHWRL1 (ORCPT ); Tue, 23 Aug 2022 13:11:27 -0400 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C7BE2AF0F2 for ; Tue, 23 Aug 2022 06:58:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1661263108; x=1692799108; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=kZQc7O6HWnTgp0S4GaudnO6gE/HwhaVoL4feiAvfF0s=; b=gZPFOc+ZK1xRZwkylHcrZ7ojfYGib+c+C37K1c8pR+GiTeTP1HZXDal9 5L0QdrZhZcxlMmT6h0TiCRLvHDymMpnXwn1BJk3A2QBcmOH6msO4nuym2 /xxPYO0ELUo2IYvMnT3JDMvb8Vxs/bmUv8fWeHhNbzLcEY9NGLt8mkDd+ K9JhUuU5wOQcqO6dfi0DKt7JEoKPGIg2+fU+Fo1+iDHf72+C61WArmNwE DuwcE1sJilPIGKBJb9ogFvBbbTx0cp77XHlluhdJ7qKrp8R4cs0UcswxF /bvw1QO500zZFB8TdlsSUbaPkItlASWN7AnCiqwMMSjKkhuhRWpCRd8G0 w==; X-IronPort-AV: E=McAfee;i="6500,9779,10448"; a="357669580" X-IronPort-AV: E=Sophos;i="5.93,257,1654585200"; d="scan'208";a="357669580" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Aug 2022 06:58:28 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,257,1654585200"; d="scan'208";a="638663365" Received: from sse-cse-haiyue-nuc.sh.intel.com ([10.239.241.114]) by orsmga008.jf.intel.com with ESMTP; 23 Aug 2022 06:58:25 -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, mike.kravetz@oracle.com, gerald.schaefer@linux.ibm.com, Haiyue Wang , Baolin Wang Subject: [PATCH v7 1/2] mm: migration: fix the FOLL_GET failure on following huge page Date: Tue, 23 Aug 2022 21:58:40 +0800 Message-Id: <20220823135841.934465-2-haiyue.wang@intel.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823135841.934465-1-haiyue.wang@intel.com> References: <20220823135841.934465-1-haiyue.wang@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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.hori= guchi@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 racin= g with memory offline") Signed-off-by: Haiyue Wang Reviewed-by: "Huang, Ying" Reviewed-by: Baolin Wang Reviewed-by: Miaohe Lin --- 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, =20 for (i =3D 0; i < nr_pages; i++) { unsigned long addr =3D (unsigned long)(*pages); + unsigned int foll_flags =3D FOLL_DUMP; struct vm_area_struct *vma; struct page *page; int err =3D -EFAULT; @@ -1856,8 +1857,12 @@ static void do_pages_stat_array(struct mm_struct *mm= , unsigned long nr_pages, if (!vma) goto set_status; =20 + /* Not all huge page follow APIs support 'FOLL_GET' */ + if (!is_vm_hugetlb_page(vma)) + foll_flags |=3D FOLL_GET; + /* FOLL_DUMP to ignore special (like zero) pages */ - page =3D follow_page(vma, addr, FOLL_GET | FOLL_DUMP); + page =3D follow_page(vma, addr, foll_flags); =20 err =3D 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, =20 if (page && !is_zone_device_page(page)) { err =3D page_to_nid(page); - put_page(page); + if (foll_flags & FOLL_GET) + put_page(page); } else { err =3D -ENOENT; } --=20 2.37.2