From nobody Sat Apr 11 08:11:55 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 AA8CDC25B06 for ; Sun, 14 Aug 2022 14:05:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239268AbiHNOFf (ORCPT ); Sun, 14 Aug 2022 10:05:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239054AbiHNOFa (ORCPT ); Sun, 14 Aug 2022 10:05:30 -0400 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D60D426F4 for ; Sun, 14 Aug 2022 07:05:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1660485928; x=1692021928; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=GYw95KnqnMAn0LnzEEb8cqb+pxBsBgkN86qaf6d0pdU=; b=cbTmB1U8rpNZTGGEeUoogj6fMUsxjuSteVFPhxLRagN7YfRUgoIbLcXy nEFWPOz0wTcd5azJJ5JZaWUvGvmjIj3OgX5VK45cQmFYpNgeerKmmTezQ zdLDDMkBIiQkbeT7biuEjQ5WWBcUtzRAdS6m5R3Zxy5YR6x5xt4PmCXaI VWnVJoDXtmit6SIh4KY3oOcL4YbEdeDb7p+vihLhnrn6nVoKPV3NEVAH4 uT71CadqlmH9+AtzZPPMbBiT0CbrupzLGT1VMe6TvwqVO00d76rjGSvbC 82+QngraFpnrs9kE/C51Wejy/0GpEoDcfKdMe7cBEYD+yN2BpZawOW4HB w==; X-IronPort-AV: E=McAfee;i="6400,9594,10439"; a="278784442" X-IronPort-AV: E=Sophos;i="5.93,236,1654585200"; d="scan'208";a="278784442" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Aug 2022 07:05:28 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,236,1654585200"; d="scan'208";a="639385189" Received: from sse-cse-haiyue-nuc.sh.intel.com ([10.239.241.114]) by orsmga001.jf.intel.com with ESMTP; 14 Aug 2022 07:05:26 -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 v2 2/3] mm: migration: fix the FOLL_GET failure on following huge page Date: Sun, 14 Aug 2022 22:05:33 +0800 Message-Id: <20220814140534.363348-3-haiyue.wang@intel.com> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220814140534.363348-1-haiyue.wang@intel.com> References: <20220812084921.409142-1-haiyue.wang@intel.com> <20220814140534.363348-1-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 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 racin= g 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 3d5f0262ab60..5d304de3950b 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) { 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