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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id AFD43C433EF for ; Tue, 19 Apr 2022 12:45:44 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 0D51E8D006E; Tue, 19 Apr 2022 08:45:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 05D298D0047; Tue, 19 Apr 2022 08:45:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E671D8D006E; Tue, 19 Apr 2022 08:45:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.a.hostedemail.com [64.99.140.24]) by kanga.kvack.org (Postfix) with ESMTP id D36338D0047 for ; Tue, 19 Apr 2022 08:45:43 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 7DD9260BCF for ; Tue, 19 Apr 2022 12:45:43 +0000 (UTC) X-FDA: 79373600166.10.4D533E1 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf29.hostedemail.com (Postfix) with ESMTP id EA79A120007 for ; Tue, 19 Apr 2022 12:45:39 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4KjNmQ3SkjzfYpn; Tue, 19 Apr 2022 20:44:38 +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; Tue, 19 Apr 2022 20:45:21 +0800 Subject: Re: [PATCH v2] mm/swapfile: unuse_pte can map random data if swap read fails To: David Hildenbrand , CC: , , , , , , , , , , , , References: <20220416030549.60559-1-linmiaohe@huawei.com> <1b614ac3-02c0-ec66-b51a-e9b7e1a375ad@huawei.com> <7308d733-1e0b-7d2e-bc34-0757555d39d6@redhat.com> From: Miaohe Lin Message-ID: <496c6285-df10-8517-c9f6-7c28162d5c80@huawei.com> Date: Tue, 19 Apr 2022 20:45:21 +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: <7308d733-1e0b-7d2e-bc34-0757555d39d6@redhat.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 X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: EA79A120007 X-Rspam-User: Authentication-Results: imf29.hostedemail.com; dkim=none; dmarc=pass (policy=quarantine) header.from=huawei.com; spf=pass (imf29.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com X-Stat-Signature: rhoz4bbm7988ssgcj4hzq85uj6173fyf X-HE-Tag: 1650372339-977969 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2022/4/19 20:12, David Hildenbrand wrote: > On 19.04.22 14:00, Miaohe Lin wrote: >> On 2022/4/19 19:46, David Hildenbrand wrote: >> ... >>>> Do you mean that we should set the pfn to 0 for the hwpoison marker so that we can >>>> distinguish swapin error case from real hwpoison case? >>> >>> I am not sure if we really have to distinguish. However, "0" seems to >>> make sense to indicate "this is not an actual problematic PFN, the >>> information is simply no longer around due to a hardware issue. >>> >> >> IMHO, we have to distinguish. For example, we might need to return VM_FAULT_SIGBUS >> instead of VM_FAULT_HWPOISON when user accesses the error page. Or should we simply >> return VM_FAULT_HWPOISON to simplify the handling? > > Hm, you're right. In e.g., x86 do_sigbus() we would send an BUS_MCEERR_AR. > > So yes, if we reuse is_hwpoison_entry() we'd have to convert to either > VM_FAULT_HWPOISON or VM_FAULT_SIGBUS. > > Something like "is_error_entry()" that can further be refined to > hwpoison or swapin could make sense. But what you have here is straight > forward to me as well. Whatever you/others prefer. IMHO, I prefer to use the separated swapin error maker because reusing hwpoison entry might make things more complicated and looks somewhat obscure. > > Acked-by: David Hildenbrand Many thanks for your Acked-by tag! > > > NIT: I'd make the terminology make_swapin_error_entry() consistent with > SWAP_READ_ERROR and especially existing SWP_. > > For example, calling the latter SWP_SWAPIN_ERROR This looks better. Thanks! Will change to rename the relevant terminology in next version if no one has an objection. :) >