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 X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3CA86C46466 for ; Thu, 8 Oct 2020 07:55:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D8C3E206F4 for ; Thu, 8 Oct 2020 07:55:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="YMmnkQY3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728968AbgJHHzP (ORCPT ); Thu, 8 Oct 2020 03:55:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52150 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728945AbgJHHzM (ORCPT ); Thu, 8 Oct 2020 03:55:12 -0400 Received: from mail-pl1-x641.google.com (mail-pl1-x641.google.com [IPv6:2607:f8b0:4864:20::641]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A32CAC0613D7; Thu, 8 Oct 2020 00:55:06 -0700 (PDT) Received: by mail-pl1-x641.google.com with SMTP id t18so2377986plo.1; Thu, 08 Oct 2020 00:55:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :in-reply-to:references; bh=c062z9g3gnR/I/VUW1enDVKC1CGF86sFMeBq5UIH9yE=; b=YMmnkQY3sdDOJ3lcgij0sPB7c7ws9B6hcVk1g8V14rp2oxxDebPKq+JUdKAtN4cxzs ebywEZ0+hJZUFFVGTNaWRqx5PueuG6qdWRvf+CDAP0N1zQ5wCM5HyFDkbjFskuP5YA+r QGSHPQj2HIxoU578u/gHISDs1ANCxD42EDBnZe44TL3/1MnICrEC1x0rU2Us0scHsDf3 jCPWqUl0bbvjvaim6QqJSf2svvXMY5Rk0pWiakSCe3BU3akz8vFMtljZHwUl9Xq4qkN7 jZikO0yA8kldHbQHXVbc7yb5OlzxOwIvcOYDOBFJpaDjNHlMmAEBHrKBD6zY1zQ5MlGn ZSig== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:in-reply-to:references; bh=c062z9g3gnR/I/VUW1enDVKC1CGF86sFMeBq5UIH9yE=; b=A5xjseC8YoHBBuJG62CjlwSD/bZR/8KWkljFGHFICCvPxEOA0iokWW9eZ5DLZ6oZO/ QkuZMUPUM6utNBfbDU95CGgghjWOYh/RMjq/IN7/KMB80pEzBNsMKQ2wD9Yr2/P9SYAk hb7KO+zc/kpgYiUAywlw3YXZmriv7pMmwSBhv8YK1vsA46+MXsQR+gpDaIHMshE36u0S nIJKIV6rxpxUWPbGlovWAIR4ZRPNHSiBjfP58n6kAT5zFvlensliJ7BPRs9jsIX/Nmmp dZb1wNM8vjs/EQmMLqZVPfNP0901CfUfVGvxsnFMadO6oxAI8/tMRxbphJLLz0AdDs2L E0pg== X-Gm-Message-State: AOAM530F6r5OL3+FesqlY1Y/NQFnUyox499DT8wKbLlLBIcmE1C7AMFb CjCJujF4Kb6SsZ4puWuUJieP4CiqDquopQ== X-Google-Smtp-Source: ABdhPJyK3jBEUk5kmaNd3EMLrw1C6cs+jFaf0qoSfvtLS36XRmTpxY9vYJHnrbHwlszIGh7v3DmGQw== X-Received: by 2002:a17:902:a9cc:b029:d3:77f7:3ca9 with SMTP id b12-20020a170902a9ccb02900d377f73ca9mr6536321plr.75.1602143706251; Thu, 08 Oct 2020 00:55:06 -0700 (PDT) Received: from localhost.localdomain ([203.205.141.61]) by smtp.gmail.com with ESMTPSA id k206sm6777106pfd.126.2020.10.08.00.55.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 08 Oct 2020 00:55:05 -0700 (PDT) From: yulei.kernel@gmail.com X-Google-Original-From: yuleixzhang@tencent.com To: akpm@linux-foundation.org, naoya.horiguchi@nec.com, viro@zeniv.linux.org.uk, pbonzini@redhat.com Cc: linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, xiaoguangrong.eric@gmail.com, kernellwp@gmail.com, lihaiwei.kernel@gmail.com, Yulei Zhang , Chen Zhuo Subject: [PATCH 18/35] mm: follow_pmd_mask() for dmem huge pmd Date: Thu, 8 Oct 2020 15:54:08 +0800 Message-Id: <25a50b534bb73164dcad1be1f7b9c48756445c3a.1602093760.git.yuleixzhang@tencent.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: References: In-Reply-To: References: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Yulei Zhang While follow_pmd_mask(), dmem huge pmd should be recognized and return error pointer of '-EEXIST' to indicate that proper page table entry exists in pmd special but no corresponding struct page, because dmem page means non struct page backend. We update pmd if foll_flags takes FOLL_TOUCH. Signed-off-by: Chen Zhuo Signed-off-by: Yulei Zhang --- mm/gup.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/mm/gup.c b/mm/gup.c index e5739a1974d5..726ffc5b0ea9 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -380,6 +380,42 @@ static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address, return -EEXIST; } +static struct page * +follow_special_pmd(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmd, unsigned int flags) +{ + spinlock_t *ptl; + + if (flags & FOLL_DUMP) + /* Avoid special (like zero) pages in core dumps */ + return ERR_PTR(-EFAULT); + + /* No page to get reference */ + if (flags & FOLL_GET) + return ERR_PTR(-EFAULT); + + if (flags & FOLL_TOUCH) { + pmd_t _pmd; + + ptl = pmd_lock(vma->vm_mm, pmd); + if (!pmd_special(*pmd)) { + spin_unlock(ptl); + return NULL; + } + _pmd = pmd_mkyoung(*pmd); + if (flags & FOLL_WRITE) + _pmd = pmd_mkdirty(_pmd); + if (pmdp_set_access_flags(vma, address & HPAGE_PMD_MASK, + pmd, _pmd, + flags & FOLL_WRITE)) + update_mmu_cache_pmd(vma, address, pmd); + spin_unlock(ptl); + } + + /* Proper page table entry exists, but no corresponding struct page */ + return ERR_PTR(-EEXIST); +} + /* * FOLL_FORCE can write to even unwritable pte's, but only * after we've gone through a COW cycle and they are dirty. @@ -564,6 +600,12 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma, return page; return no_page_table(vma, flags); } + if (pmd_special(*pmd)) { + page = follow_special_pmd(vma, address, pmd, flags); + if (page) + return page; + return no_page_table(vma, flags); + } if (is_hugepd(__hugepd(pmd_val(pmdval)))) { page = follow_huge_pd(vma, address, __hugepd(pmd_val(pmdval)), flags, -- 2.28.0