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 27554C433F5 for ; Thu, 26 May 2022 13:05:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236416AbiEZNFO (ORCPT ); Thu, 26 May 2022 09:05:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49696 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236750AbiEZNE7 (ORCPT ); Thu, 26 May 2022 09:04:59 -0400 Received: from mail-pf1-x433.google.com (mail-pf1-x433.google.com [IPv6:2607:f8b0:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC9BCCFE3E for ; Thu, 26 May 2022 06:04:58 -0700 (PDT) Received: by mail-pf1-x433.google.com with SMTP id f21so1658729pfa.3 for ; Thu, 26 May 2022 06:04:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=pBzDjNM+NIKrQwzz6yoXDKmfszuTKOxi+7+JN/0QvnU=; b=RYYRlQm8mMja6NCqEmTYUzwWQzF8s9wysfsvug3GrnVY6UaaQEwJ7hilPDM6zY4Ekz NP+VQzOI+ku/PYKSbFsJ7EdcoapEqjDGliUIWWnN0lyR7EvknmBYVVWuTpl0MJmIFkZs 9UH+r6eyPOXlbJjqIk4JMqpe3nh9qG928VTyNnDEsG/6kEsvPghzIXFb/JIWpk4ipQ8e Gk4My12oty0cIGixSF8vPpc5L0EZ2C51j/I6w6pWo0xgZv1GXZL2iZwyBu27UnNzGvWF wWtwA3pZv5Aq6TfpBr76ZD/aYnttA04WZuveVZal+HS7Nq8ojp/mhD9vCTO26i/aUevw 8OOw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=pBzDjNM+NIKrQwzz6yoXDKmfszuTKOxi+7+JN/0QvnU=; b=ZwBwfLvId3pBHblMsP+DQdoVv5mi+u3r4S7vjXdhQAvfSlQekV72RUogeC/S7Ra2BZ JsZEthK8PL6318h+k+1s8X0K95i6+YG02rB3OsGEDyjjb+6jedF5cWD2vt/QbofWmBEG H1SUVrTnHoxFno7v0cwc6WE1QbfiUxn2/KtJof0dUrh8v1nnDt1X7c1NheDPTwaTgzlE CMOxMAzl3BMWetQbkzPYsLETBaTuMjTlVJoZRj6e6ZLftmiFOFsLWxRF/y9sw65iBIyL ivCbo+PpcHDjXcRGVZZ3CjzAOlfB5GPMmEoPI5ozvKg8P3tSdPAIgQhPunCu6GxcmVvL Zh+g== X-Gm-Message-State: AOAM531EfTqnDs2ktyEX+2xMoxpHiUZWJ/3dx/BvlUbV37fv/i/zIHW7 BWAOHh/RRjrly6rCPBAKV0Hfdg== X-Google-Smtp-Source: ABdhPJyI+Gw9YzU040OsLcgsCaXngKdpfhzznfZfcU8k9dTvc3YHSPNd4XgLYgnxtJ/BHuCRqqgbVQ== X-Received: by 2002:a05:6a00:1a11:b0:512:6f59:f5cf with SMTP id g17-20020a056a001a1100b005126f59f5cfmr25386849pfv.45.1653570297993; Thu, 26 May 2022 06:04:57 -0700 (PDT) Received: from [10.5.103.226] ([139.177.225.237]) by smtp.gmail.com with ESMTPSA id t9-20020a170902b20900b001621ce92196sm1470044plr.86.2022.05.26.06.04.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 26 May 2022 06:04:57 -0700 (PDT) Message-ID: <09f38cf3-282a-61fa-9916-057b01b57d30@bytedance.com> Date: Thu, 26 May 2022 21:04:52 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH] mm/page_table_check: fix accessing unmapped ptep Content-Language: en-US To: Miaohe Lin , akpm@linux-foundation.org, pasha.tatashin@soleen.com Cc: rientjes@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20220526113350.30806-1-linmiaohe@huawei.com> From: Qi Zheng In-Reply-To: <20220526113350.30806-1-linmiaohe@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/5/26 7:33 PM, Miaohe Lin wrote: > ptep is unmapped too early, so ptep will be accessed while it's unmapped. > Fix it by deferring pte_unmap() until page table checking is done. In the beginning, page_table_check only supported x86_64, so there is no problem. But then the commit 3fee229a8eb9 ("riscv/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK") added support for riscv-32, it is indeed a problem in this case. So: Reviewed-by: Qi Zheng > > Fixes: 80110bbfbba6 ("mm/page_table_check: check entries at pmd levels") > Signed-off-by: Miaohe Lin > --- > mm/page_table_check.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/page_table_check.c b/mm/page_table_check.c > index 3692bea2ea2c..971c3129b0e3 100644 > --- a/mm/page_table_check.c > +++ b/mm/page_table_check.c > @@ -234,11 +234,11 @@ void __page_table_check_pte_clear_range(struct mm_struct *mm, > pte_t *ptep = pte_offset_map(&pmd, addr); > unsigned long i; > > - pte_unmap(ptep); > for (i = 0; i < PTRS_PER_PTE; i++) { > __page_table_check_pte_clear(mm, addr, *ptep); > addr += PAGE_SIZE; > ptep++; > } > + pte_unmap(ptep); > } > } -- Thanks, Qi