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 7D577C3DA6F for ; Fri, 25 Aug 2023 03:52:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240409AbjHYDvv (ORCPT ); Thu, 24 Aug 2023 23:51:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59192 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231174AbjHYDvl (ORCPT ); Thu, 24 Aug 2023 23:51:41 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4B0E01BEC for ; Thu, 24 Aug 2023 20:51:38 -0700 (PDT) Received: from dggpemm100001.china.huawei.com (unknown [172.30.72.57]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4RX5Z41yqwz1L9YM; Fri, 25 Aug 2023 11:50:04 +0800 (CST) Received: from [10.174.177.243] (10.174.177.243) by dggpemm100001.china.huawei.com (7.185.36.93) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Fri, 25 Aug 2023 11:51:35 +0800 Message-ID: Date: Fri, 25 Aug 2023 11:51:34 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/8] mm: migrate: remove PageTransHuge check in numamigrate_isolate_page() Content-Language: en-US To: Matthew Wilcox CC: Andrew Morton , , , , , Zi Yan , Mike Kravetz , References: <20230821115624.158759-1-wangkefeng.wang@huawei.com> <20230821115624.158759-2-wangkefeng.wang@huawei.com> From: Kefeng Wang In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm100001.china.huawei.com (7.185.36.93) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/8/21 20:38, Matthew Wilcox wrote: > On Mon, Aug 21, 2023 at 07:56:17PM +0800, Kefeng Wang wrote: >> Since we begin to convert the numa migration code to use folio, which >> could let us to handle arbitrary sizes of folio, so drop assert that >> we only support PageTransHuge page(PMD size) when order > 0. > > Have you looked at the implementation of PageTransHuge()? Your > description doesn't match what the code does. How about change to the following description， The assert VM_BUG_ON_PAGE(order && !PageTransHuge(page), page) is not very usefull, 1) for a tail/base page, order = 0, for a head page, the order > 0 && PageTransHuge() is true 2) there is a PageCompound() check and only base page is handled in do_numa_page(), and do_huge_pmd_numa_page() only handle PMD-mapped THP 3) even though the page is a tail page, isolate_lru_page() will post a warning, and fail to isolate the page. 4) and if folio migrate is supported in the future, it is probable to migrate the entire folio if numa fault on a tail page so just remove the check. Thanks