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 50F07C28D13 for ; Mon, 22 Aug 2022 08:46:53 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id C57E18D0005; Mon, 22 Aug 2022 04:46:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BDF768D0001; Mon, 22 Aug 2022 04:46:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A7FE08D0005; Mon, 22 Aug 2022 04:46:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 941DA8D0001 for ; Mon, 22 Aug 2022 04:46:52 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 66FA51601C7 for ; Mon, 22 Aug 2022 08:46:52 +0000 (UTC) X-FDA: 79826598264.20.9409F8B Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by imf02.hostedemail.com (Postfix) with ESMTP id C85B6800E6 for ; Mon, 22 Aug 2022 08:45:19 +0000 (UTC) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4MB5Tw0jGQznTgN; Mon, 22 Aug 2022 16:43:00 +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; Mon, 22 Aug 2022 16:45:16 +0800 Subject: Re: [PATCH 4/6] mm: hugetlb_vmemmap: add missing smp_wmb() before set_pte_at() To: Muchun Song CC: Andrew Morton , Mike Kravetz , Muchun Song , , References: <20220816130553.31406-1-linmiaohe@huawei.com> <20220816130553.31406-5-linmiaohe@huawei.com> From: Miaohe Lin Message-ID: Date: Mon, 22 Aug 2022 16:45:16 +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: dggems705-chm.china.huawei.com (10.3.19.182) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1661157920; a=rsa-sha256; cv=none; b=saAW643fxA+BpUve3rQ3+N4G1Qw3yHPFLerS//Hl3NA+vr9Nz5x9OEENqtGW0wvwkrpsM+ eqSV+fDzC9JBxhhhMZZG6jXv2eprilgL2wRryU7+YjmFpuwLdisLy31Pjsq3c8VtK0bTlS cQb8afTC0wHD+nu8R7TgMqAUcYIyicU= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=none; spf=pass (imf02.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1661157920; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9U3Jukuf7whCjrUJ1DjnrzeQGOsiri5GAx/F/lbWGqY=; b=SkCFF3eMRaqdJE4dO/X/I8jbXDmXmExVzEhu2Qy6fpskVOnR6276PaxpWD8byJXLCFnx4C YjMRXWqp/b6xmlnieKiWiLyxFiTt4+U52aneOEgV6rKti0XHXf0TKQrPZ+Q9uA1sZGd07g AJit2bsli6eoWh0VI5nn9gOime14hZk= X-Stat-Signature: i3wycdyfbzrefrmm3em8o9rwf6n8n3xg X-Rspamd-Queue-Id: C85B6800E6 Authentication-Results: imf02.hostedemail.com; dkim=none; spf=pass (imf02.hostedemail.com: domain of linmiaohe@huawei.com designates 45.249.212.187 as permitted sender) smtp.mailfrom=linmiaohe@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1661157919-483493 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 2022/8/20 16:12, Muchun Song wrote: > > >> On Aug 16, 2022, at 21:05, Miaohe Lin wrote: >> >> The memory barrier smp_wmb() is needed to make sure that preceding stores >> to the page contents become visible before the below set_pte_at() write. > > I found another place where is a similar case. See kasan_populate_vmalloc_pte() in > mm/kasan/shadow.c. Thanks for your report. > > Should we fix it as well? I'm not familiar with kasan yet, but I think memory barrier is needed here or memory corrupt can't be detected until the contents are visible. smp_mb__after_atomic before set_pte_at should be enough? What's your opinion? Thanks, Miaohe Lin