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 CF14FC433EF for ; Thu, 26 May 2022 13:11:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3B9A58D0003; Thu, 26 May 2022 09:11:47 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 365C68D0002; Thu, 26 May 2022 09:11:47 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 255D48D0003; Thu, 26 May 2022 09:11:47 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 15C6E8D0002 for ; Thu, 26 May 2022 09:11:47 -0400 (EDT) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id CF01533B31 for ; Thu, 26 May 2022 13:11:46 +0000 (UTC) X-FDA: 79507931412.11.C765FBA Received: from mail-ej1-f42.google.com (mail-ej1-f42.google.com [209.85.218.42]) by imf08.hostedemail.com (Postfix) with ESMTP id 2D30E160041 for ; Thu, 26 May 2022 13:11:24 +0000 (UTC) Received: by mail-ej1-f42.google.com with SMTP id wh22so2950873ejb.7 for ; Thu, 26 May 2022 06:11:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=soleen.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Nt+n2haklMuWStLRmgRtCfZgoN7afB/xjurnhlibBtA=; b=mdh4hUALSiiYooecz2d11OWfKfPev1AO99H5MjRa6BV8gFhSR5KjdOV7L8lCUi701X 3oE6KQ+1Pz6HNtSdOhN1ac/v1j7/wpJtJXG1c7Dh3jy9720CFNKoHEiAKmaYWREiK0ud YPTCe4Pc+4v24AnQM0uCl3U+MMV2GfyF3FlVlTaUgBDtnVSPu1My2a5HuiHpmoSOG1mv h2D8npJzXAq8jGEnX4q+C/5kLLFJGhzC4EXV/j+51zADBGxTb5cAvm9GkoMGrWR/n9dW F/fQMJIw96OTAOdjrFD8j/ghyoWQhiLQbiCcljv/HWdzPJ0F3RK7VneNeFgQnQq4WV71 GF3g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Nt+n2haklMuWStLRmgRtCfZgoN7afB/xjurnhlibBtA=; b=2vXgochhThtTWgxLwY0QdgVff8A3c7ht2rqRzFZrG95ljdOZJWXPKXRU31odpS0+cZ EsCIK64oFcg4GSfVpGSRfSUEE+dD380vhFX+58Iq8B17A/KAcgvD9Q3rJfMRlD0Jfp0H pgC8NN9I+WZqFnaMB9PbFGHb6sT0SJVyeg4NxKmRgXdChP/vB7e8LW4ihSRfkoV6yv4M N1UL/1hP0Qoo/3DhyjR/SisZWw2Wd7i0ORNZKdZD2hkwPzeMznIYu3BhVxbj7FgPa+JU 3PJKQkI8bIW3HSaApaGDPc5mDZ05pLTH1rPPg0MauaApv/emqctAfCCOYeixRVeK5vRl PU9w== X-Gm-Message-State: AOAM532vQZoWYZVhgUxlUM4WB5A+sYXijbVpcy9u0VUKXPzUx5HH8cc+ emGeP8h1GU5DjKY5Fq9V3BwVBjuOfZIPu9Q2aZYNeQ== X-Google-Smtp-Source: ABdhPJyVOJFJpwtgzyvTJVh+RCxHEKoowBQj8NU7m0i1XTs+8LBvYgl44pjc658B2YptHEliXFJqRdQ1QdhtiUwI7so= X-Received: by 2002:a17:907:86a9:b0:6ff:45d:c05b with SMTP id qa41-20020a17090786a900b006ff045dc05bmr11989570ejc.492.1653570704863; Thu, 26 May 2022 06:11:44 -0700 (PDT) MIME-Version: 1.0 References: <20220526113350.30806-1-linmiaohe@huawei.com> <09f38cf3-282a-61fa-9916-057b01b57d30@bytedance.com> In-Reply-To: <09f38cf3-282a-61fa-9916-057b01b57d30@bytedance.com> From: Pasha Tatashin Date: Thu, 26 May 2022 09:11:07 -0400 Message-ID: Subject: Re: [PATCH] mm/page_table_check: fix accessing unmapped ptep To: Qi Zheng Cc: Miaohe Lin , Andrew Morton , David Rientjes , linux-mm , LKML Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 2D30E160041 X-Stat-Signature: d8uzo6zu7dh36dasno5cy9jdqni6xjw9 X-Rspam-User: Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=soleen.com header.s=google header.b=mdh4hUAL; spf=pass (imf08.hostedemail.com: domain of pasha.tatashin@soleen.com designates 209.85.218.42 as permitted sender) smtp.mailfrom=pasha.tatashin@soleen.com; dmarc=none X-HE-Tag: 1653570684-412589 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 Thu, May 26, 2022 at 9:04 AM Qi Zheng wrote: > > > > 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. pte_unmap() is needed only with CONFIG_HIGHPTE. I do not see this config for riskv-32? Pasha > > 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