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 B1F2CC433F5 for ; Sun, 24 Apr 2022 10:03:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E9CCD6B0074; Sun, 24 Apr 2022 06:02:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E4B266B0075; Sun, 24 Apr 2022 06:02:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D12846B0078; Sun, 24 Apr 2022 06:02:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.26]) by kanga.kvack.org (Postfix) with ESMTP id BEC5D6B0074 for ; Sun, 24 Apr 2022 06:02:59 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 9A85828BB2 for ; Sun, 24 Apr 2022 10:02:59 +0000 (UTC) X-FDA: 79391334078.30.5E4D59B Received: from out30-45.freemail.mail.aliyun.com (out30-45.freemail.mail.aliyun.com [115.124.30.45]) by imf20.hostedemail.com (Postfix) with ESMTP id 246DC1C004A for ; Sun, 24 Apr 2022 10:02:55 +0000 (UTC) X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R571e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04400;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0VB0eh7g_1650794574; Received: from 30.39.210.25(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VB0eh7g_1650794574) by smtp.aliyun-inc.com(127.0.0.1); Sun, 24 Apr 2022 18:02:54 +0800 Message-ID: <4526be44-696b-9719-5a00-6002f61aec01@linux.alibaba.com> Date: Sun, 24 Apr 2022 18:03:32 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH] mm: hugetlb: Add missing cache flushing in hugetlb_unshare_all_pmds() To: Muchun Song Cc: akpm@linux-foundation.org, mike.kravetz@oracle.com, peterx@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <419b0e777c9e6d1454dcd906e0f5b752a736d335.1650781755.git.baolin.wang@linux.alibaba.com> From: Baolin Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: t667neyhjxbde5sxicbyyrjtbh34qqdt X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 246DC1C004A X-Rspam-User: Authentication-Results: imf20.hostedemail.com; dkim=none; spf=pass (imf20.hostedemail.com: domain of baolin.wang@linux.alibaba.com designates 115.124.30.45 as permitted sender) smtp.mailfrom=baolin.wang@linux.alibaba.com; dmarc=pass (policy=none) header.from=alibaba.com X-HE-Tag: 1650794575-433225 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 4/24/2022 3:45 PM, Muchun Song wrote: > On Sun, Apr 24, 2022 at 02:33:19PM +0800, Baolin Wang wrote: >> Missed calling flush_cache_range() before removing the sharing PMD entrires, >> otherwise data consistence issue may be occurred on some architectures whose >> caches are strict and require a virtual–>physical translation to exist for >> a virtual address. Thus add it. >> >> Fixes: 6dfeaff93be1 ("hugetlb/userfaultfd: unshare all pmds for hugetlbfs when register wp") >> Signed-off-by: Baolin Wang > > CONFIG_ARCH_WANT_HUGE_PMD_SHARE is only definded on riscv, arm64 and > x86. All of them do not have a VIVT cache. In others words, > flush_cache_range() is null on those architectures. So I suspect > in practice this does not cause any issue. It is better to > clarify this in commit log. Yes, just from code inspection and to keep same behaviors when unmapping sharing PMD entrires in case more architectures can support CONFIG_ARCH_WANT_HUGE_PMD_SHARE in future. Will update the commit message in next version. > > Anyway: > > Reviewed-by: Muchun Song Thanks.