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 A4B22C433F5 for ; Wed, 20 Apr 2022 08:37:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1376773AbiDTIjz (ORCPT ); Wed, 20 Apr 2022 04:39:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60914 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1376768AbiDTIjx (ORCPT ); Wed, 20 Apr 2022 04:39:53 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EF7452A242 for ; Wed, 20 Apr 2022 01:37:07 -0700 (PDT) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.55]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4Kjv7D3rd1zCrbG; Wed, 20 Apr 2022 16:32:40 +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, 20 Apr 2022 16:37:05 +0800 Subject: Re: [PATCH v2] mm/swapfile: unuse_pte can map random data if swap read fails To: David Hildenbrand , Alistair Popple CC: , , , , , , , , , , , , References: <20220416030549.60559-1-linmiaohe@huawei.com> <87tuapk9n7.fsf@nvdebian.thelocal> <87r15tjy76.fsf@nvdebian.thelocal> <87k0bkk2rp.fsf@nvdebian.thelocal> <6cf3726c-d6d0-4255-2deb-3688227c633e@huawei.com> From: Miaohe Lin Message-ID: <4d14dcfc-0053-bfd6-433e-f264d22069d0@huawei.com> Date: Wed, 20 Apr 2022 16:37:04 +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: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) 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 2022/4/20 15:07, David Hildenbrand wrote: > On 20.04.22 08:15, Miaohe Lin wrote: >> On 2022/4/20 8:25, Alistair Popple wrote: >>> Miaohe Lin writes: >>> >>>> On 2022/4/19 15:53, Alistair Popple wrote: >>>>> Also in madvise_free_pte_range() you could just remove the swap entry as it's no >>>>> longer needed. >>>>> >>>> >>>> This swap entry will be removed in madvise_dontneed_single_vma(). >>>> And in madvise_free_pte_range(), we may need to keep it as same as >>>> hwpoison entry. Or am I supposed to remove it even if hwpoison entry >>>> is reused later? >>> >>> Why would we need to keep it for MADV_FREE though? It only works on private >>> anonymous memory, and once the MADV_FREE operation has succeeded callers can >>> expect they might get zero-fill pages if accessing the memory again. Therefore >>> it should be safe to delete the entry. I think that applies equally to a >>> hwpoison entry too - there's no reason to kill the process if it has called >>> MADV_FREE on the range. >> >> I tend to agree. We can drop the swapin error entry and hwpoison entry when MADV_FREE >> is called. Should I squash these into the current patch or a separate one is preferred? >> > > That should go into a separate patch. Will do. Many thanks for your suggestion. >