Received: by 2002:a05:6358:3188:b0:123:57c1:9b43 with SMTP id q8csp2318623rwd; Wed, 17 May 2023 08:28:29 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ7XfauevHhVSZu6rTi7prr8JDKqtgc8nJKRCRMn3zQmV3Rzeb+BWbK9IjyDZ3TYSnckKs3V X-Received: by 2002:a05:6a20:3d8a:b0:105:5caa:b49c with SMTP id s10-20020a056a203d8a00b001055caab49cmr18501102pzi.23.1684337309496; Wed, 17 May 2023 08:28:29 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1684337309; cv=none; d=google.com; s=arc-20160816; b=kimLARm2Bf1WCSHQtwVpoCt33VEMWIQiWjc7m+eBwOUHu+OIFz6ee59ZXaBLUqa4Fh 3tFkR8ONQAYnmOqkifHAOjWuZKc7AquEvp0v5q8zyQPd0LbjaCFKtAdy5gd4UnCn2NKT WWERyYy/h5+9Gbk86+u0S06rqk6vXTOa2QxWvnMBhtLURbL+75rQRHKfnjsyVIuYQmEu SCORcTqjNw3A/hrZb7Uv7qoW4IhpMzrX5lOAitGSo6RVNTYYuQ/2aVKE7FuocP2l5s8t D3eYIbp0iKZeb4tGIGTB+ZRehuFSn0VXO/z6CFeFIjAuFbqAIyLj0xs62yX+yUsHjXev Enxw== 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=Ms+Yw6xLDbHeWgltH2GeZ/mYx1EXxuQy0fD+zKwpp0k=; b=ONd55KPcEdgLLUdSfYo985GNk3vSPvoxHiPWSK2blXurW6i9kQlTd7FJtkRyg5xT7y oEJ7q1Q2Pn6aOLKgWd6yftBcfNpYHdLB1/xAgqlnI69IUILiOdhE+9u+FXIVuHXmg7L2 2kaTfHVWZT6Sw9+AY56jXFKNepNgVEcSy+FBh0dZs93AwZ9gF8ouPO0XUg2YqLCYjd7J lJ9stXAvvlHNE0xBMlfU0Z36s+1HS70eO2hN1Rdo8PQ+tRm0rLF8ete3ZIDNCkdnKbAn UiZZwMjXvk/VliK9uqq5gUHA0h7PqXYrQi9/KkbEGtfnxzhhLdSK6h3JDfnlYJ2UBThX ZBxw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=gUgCtHWV; 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=NONE sp=NONE dis=NONE) header.from=redhat.com Return-Path: Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id m2-20020a637d42000000b005306facab05si16041476pgn.120.2023.05.17.08.28.17; Wed, 17 May 2023 08:28:29 -0700 (PDT) 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=@redhat.com header.s=mimecast20190719 header.b=gUgCtHWV; 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=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231676AbjEQPGn (ORCPT + 99 others); Wed, 17 May 2023 11:06:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32780 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231769AbjEQPG0 (ORCPT ); Wed, 17 May 2023 11:06:26 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 95B31A5C4 for ; Wed, 17 May 2023 08:05:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1684335885; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Ms+Yw6xLDbHeWgltH2GeZ/mYx1EXxuQy0fD+zKwpp0k=; b=gUgCtHWV+6U//UcbdmPRdwiZR/+CfGY0UyX4Om2P0oIJo79KwiEcZ6h5uNfNjuA/An4BjL 5sOfBD6ZK6+KFJtTHZsjIKL3RAdjCoBoP5rL+djO7GPAkPKZHf+2dZPw3Fphd8xkYsDtDc LdpgNvc2X219neQkSA1tgoWAbDEPSaU= Received: from mail-qt1-f198.google.com (mail-qt1-f198.google.com [209.85.160.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-422-bG2_vudaOT2Z1n_fYIu0ig-1; Wed, 17 May 2023 11:04:18 -0400 X-MC-Unique: bG2_vudaOT2Z1n_fYIu0ig-1 Received: by mail-qt1-f198.google.com with SMTP id d75a77b69052e-3f387d3b41eso1457741cf.1 for ; Wed, 17 May 2023 08:04:17 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684335855; x=1686927855; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Ms+Yw6xLDbHeWgltH2GeZ/mYx1EXxuQy0fD+zKwpp0k=; b=Z8x4v8ItF51IY3uqkJx76/gn2tIKXYt1+mkxJefHqDAQa35xR4xiJrk6CkhgwOSn4B s4kM6uR/GEDmukE3vsZwWy6BLBJyVUIZLeFV12tDbdduRJ9aErm3Q2TSwyZ2RlwHiEjR uK0i4qBkBxfQrCimxZ5CYsdQjeheOZcp/bCAq0tufZVVbEy/qoKgVV4m6CMQ5J3hL7MR bt+JAZVxcjNG4165X83DrEETVbEaN5bOEcigJIPkU7tqWuq6znbZiLuMRGEV+7BR5Vsm /6GC6FHHN2qCjOfJrvB3fTDEYzg0x5CweId6Hu9V3NTn14ll9vwMgRlrWfopyGvqaRXN tn0w== X-Gm-Message-State: AC+VfDwZGC5Y53vIL9lKEaU9ebpDZH10HmyGfF8SN1cbE4lfKiHtpGZt 10BPU9ouR9/woUC/imWrQkt7yedGIY5U+jWxsSZfKxzBRsgNOmMWZExqeDwgwCh0IU2tXF89fz8 pUKbaKh4FiSWw40G4RSutZJa0AXOLbkaoCiQOFzwPK9rMVpxOYlwIWt47Gqxayy4IXzB1pSgCVh h0EAgQ3w== X-Received: by 2002:a05:622a:1a9e:b0:3f4:e9bc:22e with SMTP id s30-20020a05622a1a9e00b003f4e9bc022emr5674309qtc.6.1684335854967; Wed, 17 May 2023 08:04:14 -0700 (PDT) X-Received: by 2002:a05:622a:1a9e:b0:3f4:e9bc:22e with SMTP id s30-20020a05622a1a9e00b003f4e9bc022emr5674272qtc.6.1684335854592; Wed, 17 May 2023 08:04:14 -0700 (PDT) Received: from x1n.. (bras-base-aurron9127w-grc-62-70-24-86-62.dsl.bell.ca. [70.24.86.62]) by smtp.gmail.com with ESMTPSA id u10-20020a05620a120a00b0074d4cf8f9fcsm661141qkj.107.2023.05.17.08.04.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 May 2023 08:04:13 -0700 (PDT) From: Peter Xu To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Lorenzo Stoakes , Andrew Morton , "Liam R . Howlett" , Mark Rutland , Andrea Arcangeli , Mike Rapoport , peterx@redhat.com, Alexander Viro , linux-stable Subject: [PATCH 2/2] mm/uffd: Allow vma to merge as much as possible Date: Wed, 17 May 2023 11:04:08 -0400 Message-Id: <20230517150408.3411044-3-peterx@redhat.com> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230517150408.3411044-1-peterx@redhat.com> References: <20230517150408.3411044-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=unavailable 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 We used to not pass in the pgoff correctly when register/unregister uffd regions, it caused incorrect behavior on vma merging and can cause mergeable vmas being separate after ioctls return. For example, when we have: vma1(range 0-9, with uffd), vma2(range 10-19, no uffd) Then someone unregisters uffd on range (5-9), it should logically become: vma1(range 0-4, with uffd), vma2(range 5-19, no uffd) But with current code we'll have: vma1(range 0-4, with uffd), vma3(range 5-9, no uffd), vma2(range 10-19, no uffd) This patch allows such merge to happen correctly before ioctl returns. This behavior seems to have existed since the 1st day of uffd. Since pgoff for vma_merge() is only used to identify the possibility of vma merging, meanwhile here what we did was always passing in a pgoff smaller than what we should, so there should have no other side effect besides not merging it. Let's still tentatively copy stable for this, even though I don't see anything will go wrong besides vma being split (which is mostly not user visible). Cc: Andrea Arcangeli Cc: Mike Rapoport (IBM) Cc: linux-stable Fixes: 86039bd3b4e6 ("userfaultfd: add new syscall to provide memory externalization") Signed-off-by: Peter Xu --- fs/userfaultfd.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 17c8c345dac4..4e800bb7d2ab 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1332,6 +1332,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, bool basic_ioctls; unsigned long start, end, vma_end; struct vma_iterator vmi; + pgoff_t pgoff; user_uffdio_register = (struct uffdio_register __user *) arg; @@ -1484,8 +1485,9 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, vma_end = min(end, vma->vm_end); new_flags = (vma->vm_flags & ~__VM_UFFD_FLAGS) | vm_flags; + pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); prev = vma_merge(&vmi, mm, prev, start, vma_end, new_flags, - vma->anon_vma, vma->vm_file, vma->vm_pgoff, + vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), ((struct vm_userfaultfd_ctx){ ctx }), anon_vma_name(vma)); @@ -1565,6 +1567,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, unsigned long start, end, vma_end; const void __user *buf = (void __user *)arg; struct vma_iterator vmi; + pgoff_t pgoff; ret = -EFAULT; if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister))) @@ -1667,8 +1670,9 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, uffd_wp_range(vma, start, vma_end - start, false); new_flags = vma->vm_flags & ~__VM_UFFD_FLAGS; + pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); prev = vma_merge(&vmi, mm, prev, start, vma_end, new_flags, - vma->anon_vma, vma->vm_file, vma->vm_pgoff, + vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), NULL_VM_UFFD_CTX, anon_vma_name(vma)); if (prev) { -- 2.39.1