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 D37DFC32771 for ; Wed, 17 Aug 2022 02:34:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238161AbiHQCeS (ORCPT ); Tue, 16 Aug 2022 22:34:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45046 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238100AbiHQCeQ (ORCPT ); Tue, 16 Aug 2022 22:34:16 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1981550054 for ; Tue, 16 Aug 2022 19:34:15 -0700 (PDT) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4M6sRs3dvMzXdNr; Wed, 17 Aug 2022 10:30:01 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Wed, 17 Aug 2022 10:34:12 +0800 Subject: Re: [PATCH v6 2/2] mm: fix the handling Non-LRU pages returned by follow_page To: Haiyue Wang , , CC: , , , , , , , Felix Kuehling References: <20220812084921.409142-1-haiyue.wang@intel.com> <20220816022102.582865-1-haiyue.wang@intel.com> <20220816022102.582865-3-haiyue.wang@intel.com> From: Miaohe Lin Message-ID: Date: Wed, 17 Aug 2022 10:34:12 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20220816022102.582865-3-haiyue.wang@intel.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/8/16 10:21, Haiyue Wang wrote: > The handling Non-LRU pages returned by follow_page() jumps directly, it > doesn't call put_page() to handle the reference count, since 'FOLL_GET' > flag for follow_page() has get_page() called. Fix the zone device page > check by handling the page reference count correctly before returning. > > And as David reviewed, "device pages are never PageKsm pages". Drop this > zone device page check for break_ksm(). > > Fixes: 3218f8712d6b ("mm: handling Non-LRU pages returned by vm_normal_pages") > Signed-off-by: Haiyue Wang > Reviewed-by: "Huang, Ying" > Reviewed-by: Felix Kuehling Thanks for your fixing. LGTM with one nit below. But I have no strong opinion on it. So with or without fixing below nit: Reviewed-by: Miaohe Lin > --- > mm/huge_memory.c | 4 ++-- > mm/ksm.c | 12 +++++++++--- > mm/migrate.c | 19 ++++++++++++------- > 3 files changed, 23 insertions(+), 12 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 8a7c1b344abe..b2ba17c3dcd7 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2963,10 +2963,10 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start, > /* FOLL_DUMP to ignore special (like zero) pages */ > page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP); > > - if (IS_ERR_OR_NULL(page) || is_zone_device_page(page)) > + if (IS_ERR_OR_NULL(page)) > continue; > > - if (!is_transparent_hugepage(page)) > + if (is_zone_device_page(page) || !is_transparent_hugepage(page)) !is_transparent_hugepage should already do the work here? IIRC, zone_device_page can't be a transhuge page anyway. And only transparent_hugepage is cared here. Thanks, Miaohe Lin