From patchwork Thu Feb 16 06:41:54 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muhammad Usama Anjum X-Patchwork-Id: 57887 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:adf:eb09:0:0:0:0:0 with SMTP id s9csp146207wrn; Wed, 15 Feb 2023 22:54:28 -0800 (PST) X-Google-Smtp-Source: AK7set//glBgZrh9BqXIFntjLSRp+h/CfCJvAqsF1SlHO3ebefz7eAvosvkwEd63S8oxTbfkEbPL X-Received: by 2002:a17:90b:390c:b0:22b:b282:a9d7 with SMTP id ob12-20020a17090b390c00b0022bb282a9d7mr1145844pjb.20.1676530468484; Wed, 15 Feb 2023 22:54:28 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1676530468; cv=none; d=google.com; s=arc-20160816; b=BQeO0uLYNAyawKCYr3P6gYFUEVyrsHGIHu4r0nmmqPBJe+vEbZrx75gLfQXY9DBndK OAj09xVWijsg2m736Hk4v9VYRKAdnhXQvGzPmLWMG3SiEgjv0GXefMRGDMr7GpSyB3Ww DsyRUZUPAG9Y5QS5WbwxQrR9O4qNTybN+5ZOcSiVCmo3RyHtkz16beFDeHVfI8Dm2m6B yKBz4177rQvm79DAygPjUSZ8vfKAZgE+zXNSH414AFB+pbx718VG2sqjgmxbEmQGQfgo LddKp9vSNQVrXoQmE2lS2PAkHe217Rjy0Bz5COCesdgY2bd10ZJcy0lwROzvaVSNy5jT ZzUg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :message-id:date:subject:cc:to:from:dkim-signature; bh=lIU1YSifQgqy5vKkdAoTh04iH/wSOwAbT9lrRt71a+I=; b=ZOBfX78GjEUSKWnIc7AmvAWi8FCBVPvZsRtoTuzPNRA2Ijz4mB3zB8TJMm8abDpSC2 d+eBoZ8RDRokCgYHRNVUn21v0hUTxGntBiBkg5v0wpkCgPL1M+igMwr3ON5re69WX/AZ Z3Cd0DYACvljBwDpgCTkB0H4DSxSuXNN0qxwvHWxIDGNOu2O+IexF1Ahn2n5tDZIIe9V HtQ+8iESlHXk16CSgRMiRctTPAHf82mSgKjvlMCni6O8u3tp8JUNbtfX3nYlCSaO77bh +n80IIMsIh/gwXhUk4wzDjIbZywfB6JSmWBmAHgQ+KfP+dvQBV6Yiw41uuh1v9p97MCU qm6g== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@collabora.com header.s=mail header.b=GkeuNID2; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=collabora.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id v23-20020a17090a459700b0022c4e0720b6si3868230pjg.115.2023.02.15.22.54.15; Wed, 15 Feb 2023 22:54:28 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@collabora.com header.s=mail header.b=GkeuNID2; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=collabora.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229539AbjBPGm3 (ORCPT + 99 others); Thu, 16 Feb 2023 01:42:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45796 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229592AbjBPGm0 (ORCPT ); Thu, 16 Feb 2023 01:42:26 -0500 Received: from madras.collabora.co.uk (madras.collabora.co.uk [46.235.227.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1FD0735B4 for ; Wed, 15 Feb 2023 22:42:23 -0800 (PST) Received: from localhost.localdomain (unknown [39.45.217.110]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: usama.anjum) by madras.collabora.co.uk (Postfix) with ESMTPSA id 7517C660215E; Thu, 16 Feb 2023 06:42:19 +0000 (GMT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1676529742; bh=BZYuBCeCugmy4mw2Nhoe/U7I5Z6mqKYkAE3a/WqYnEQ=; h=From:To:Cc:Subject:Date:From; b=GkeuNID2I8NnX4wJVAJsXUfQkgPZyOZKR+eVujKQ09Y3AbRJ8FZFsN7U4ooRlFFoZ fnP8+JZOMcVFRime6Bov4K9XY1mBpR2qjfvkn0FL+V4g3HERnBXL+j0SdLBjjQwFIl kmvRMnoOawcDoN9e2RConX+4bvsTyXBuh2TDMn5Om4sh2RVYW+IJHUj2cGdy5xJQK5 GfakwV3k9bfLmv9AWttXoGO6OGGiNqcVikmBrEWpJDPyFTuv2Kdo/ml5+Q5N2fO6Zw 34DTtYe+HXIidPiVZ7VQ0SYA/GE/ORWBCeMwhD0GfwYNrNZ3lbqgPJ0tCyDk9+G/+w lLZyOC26N2LGw== From: Muhammad Usama Anjum To: peterx@redhat.com, david@redhat.com, Andrew Morton Cc: Muhammad Usama Anjum , kernel@collabora.com, Paul Gofman , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 1/2] mm/userfaultfd: Support WP on multiple VMAs Date: Thu, 16 Feb 2023 11:41:54 +0500 Message-Id: <20230216064155.1500545-1-usama.anjum@collabora.com> X-Mailer: git-send-email 2.39.1 MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1757735339494299958?= X-GMAIL-MSGID: =?utf-8?q?1757969612770151217?= mwriteprotect_range() errors out if [start, end) doesn't fall in one VMA. We are facing a use case where multiple VMAs are present in one range of interest. For example, the following pseudocode reproduces the error which we are trying to fix: - Allocate memory of size 16 pages with PROT_NONE with mmap - Register userfaultfd - Change protection of the first half (1 to 8 pages) of memory to PROT_READ | PROT_WRITE. This breaks the memory area in two VMAs. - Now UFFDIO_WRITEPROTECT_MODE_WP on the whole memory of 16 pages errors out. This is a simple use case where user may or may not know if the memory area has been divided into multiple VMAs. We need an implementation which doesn't disrupt the already present users. So keeping things simple, stop going over all the VMAs if any one of the VMA hasn't been registered in WP mode. While at it, remove the un-needed error check as well. Reported-by: Paul Gofman Signed-off-by: Muhammad Usama Anjum --- Changes since v2: - Correct the return error code and cleanup a bit Changes since v1: - Correct the start and ending values passed to uffd_wp_range() --- mm/userfaultfd.c | 35 ++++++++++++++++++++--------------- 1 file changed, 20 insertions(+), 15 deletions(-) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 65ad172add27..366dc097ab11 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -738,9 +738,12 @@ int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, unsigned long len, bool enable_wp, atomic_t *mmap_changing) { + unsigned long end = start + len; + unsigned long _start, _end; struct vm_area_struct *dst_vma; unsigned long page_mask; int err; + VMA_ITERATOR(vmi, dst_mm, start); /* * Sanitize the command parameters: @@ -763,25 +766,27 @@ int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, goto out_unlock; err = -ENOENT; - dst_vma = find_dst_vma(dst_mm, start, len); + for_each_vma_range(vmi, dst_vma, end) { - if (!dst_vma) - goto out_unlock; - if (!userfaultfd_wp(dst_vma)) - goto out_unlock; - if (!vma_can_userfault(dst_vma, dst_vma->vm_flags)) - goto out_unlock; + if (!userfaultfd_wp(dst_vma)) { + err = -ENOENT; + break; + } - if (is_vm_hugetlb_page(dst_vma)) { - err = -EINVAL; - page_mask = vma_kernel_pagesize(dst_vma) - 1; - if ((start & page_mask) || (len & page_mask)) - goto out_unlock; - } + if (is_vm_hugetlb_page(dst_vma)) { + err = -EINVAL; + page_mask = vma_kernel_pagesize(dst_vma) - 1; + if ((start & page_mask) || (len & page_mask)) + break; + } + + _start = max(dst_vma->vm_start, start); + _end = min(dst_vma->vm_end, end); - uffd_wp_range(dst_mm, dst_vma, start, len, enable_wp); + uffd_wp_range(dst_mm, dst_vma, _start, _end - _start, enable_wp); - err = 0; + err = 0; + } out_unlock: mmap_read_unlock(dst_mm); return err; From patchwork Thu Feb 16 06:41:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Muhammad Usama Anjum X-Patchwork-Id: 57888 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:adf:eb09:0:0:0:0:0 with SMTP id s9csp148001wrn; Wed, 15 Feb 2023 22:59:57 -0800 (PST) X-Google-Smtp-Source: AK7set8YjzWjfMvB74Eq4HPg9w2XnUdOll0tnNcaMp/L+C2N/m8yH6JrZdvC2gN2JLjGgYfByVMy X-Received: by 2002:a17:906:af8c:b0:878:61d8:d7c2 with SMTP id mj12-20020a170906af8c00b0087861d8d7c2mr5164806ejb.39.1676530797009; Wed, 15 Feb 2023 22:59:57 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1676530796; cv=none; d=google.com; s=arc-20160816; b=TkUaCK0IxUyP+C1b+pUtzHixL4nn/cRer1Zb76aYvt8U+U9wwnVk3TH8NBIGDEAhGe bKO5qTJ0JpaXYTtRQ2DWJ22ngt5yZA1Kr/FCXZBzx1ReC3AJujYXgCEUaKib4JNXWdcn 7zcwRf0QAMNbW3kWP/ybdlGIdb/FTFgYqN6XueRxyOjxL5lrK2A7UT8RLPmMv7XHNzpI g1AHpkEjy8pFaPw6Y4uhCh3ZbE87OKoPB+ADhaEFnGgOzFnatggJV1xaxTx0Otz0mH0S N5d1CAfl+5lbDB+R2hwm6ipHvKWSjyRUdqNeSk/kiY46MvkM6z+j9xYNZmk55wQH36dN +PdA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=ljirQrVNPG5UDLJtYd2F8HCRXiJQ1e82Nq6Ygyb5EHw=; b=onfSpj8KYWOv/eybTva2Q7C2UT7z3rSe09zuIN3URoz+YutqwTGpf1FBCNPeb/tGrB pnHz/mx5Lw6epca1A331jdAQO4VTsIlVuJdECGfo6Q2xBtj2CrgrhaRAfy3MyYzr6+g4 nKpEUE3vsJiLBN5wzQhVV3OW7ePe+Bipejvx4Wlp1VyOBVnQZqa8xr3lqAd7jfMWFc64 K8LeMY2+LvvOZbPRXCMXGNS+braPAdtTMxroZlRsYXCb65vJejHdGDzxcIdTRigXwpuA xZ4gaHo3DqxH1lMeiJPiByJltMD4wiHWDJ7PoCJUxrVHhKmv4I2o19EWxZ2kQ68GEsWX ciFA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@collabora.com header.s=mail header.b=gtjiguMc; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=collabora.com Received: from out1.vger.email (out1.vger.email. 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Signed-off-by: Muhammad Usama Anjum --- mm/userfaultfd.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 366dc097ab11..9db77c36ef18 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -716,6 +716,8 @@ void uffd_wp_range(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma, unsigned int mm_cp_flags; struct mmu_gather tlb; + VM_WARN_ONCE(start < dst_vma->vm_start || start + len > dst_vma->vm_end, + "The address range exceeds VMA boundary.\n"); if (enable_wp) mm_cp_flags = MM_CP_UFFD_WP; else