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 314CCC19F2D for ; Tue, 9 Aug 2022 20:23:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id BB9E38E0008; Tue, 9 Aug 2022 16:23:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B69498E0001; Tue, 9 Aug 2022 16:23:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A09B58E0008; Tue, 9 Aug 2022 16:23:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 91BBD8E0001 for ; Tue, 9 Aug 2022 16:23:56 -0400 (EDT) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 648FE1210DB for ; Tue, 9 Aug 2022 20:23:56 +0000 (UTC) X-FDA: 79781180472.18.A15AB89 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf04.hostedemail.com (Postfix) with ESMTP id D8E5440021 for ; Tue, 9 Aug 2022 20:23:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1660076635; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ks5e3vG8/bg6ecSj9dekO7KiLf2ruNOcJnb5Pq8KV1g=; b=IZ2bYdl4logQ+DAA4t8ZUEcP2wsAVxNc7wF5PPpgxdDVm3kJaM5Rsnv0U+tx1CW/+KkBn7 GAQyhMwqBVNRAAxe+FxIbhW/6U1dSAcEBJA8VSS7XwiXHx5hdjJQ9VzClugz6+MgfGu8fT Yj2dlN0E17HC0pVO1IYWA0CCXIZ20ec= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-606-uWw-G7EYMD-_FjWVFqWRng-1; Tue, 09 Aug 2022 16:23:51 -0400 X-MC-Unique: uWw-G7EYMD-_FjWVFqWRng-1 Received: by mail-wm1-f72.google.com with SMTP id c17-20020a7bc011000000b003a2bfaf8d3dso6491455wmb.0 for ; Tue, 09 Aug 2022 13:23:51 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:organization:from:references :cc:to:content-language:subject:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc; bh=ks5e3vG8/bg6ecSj9dekO7KiLf2ruNOcJnb5Pq8KV1g=; b=HTVo9fUTYJGe4rHaRAZNVl2fqVeEK+khOLupYb/t5bpPr6NaEh2tnOwqmOihvVU7TW elf/5DJye+cWAfBcgftinrnfjQIESXq9nL8IrRXcJm9UxgtPyCSpuh358UczXrnGbkIb SgWgsYzjlAhqQEqwkIRTG9S6N5sCttv2uUqp3cP0NEoeYLOUMm/0eWkAfixAeHXzymEl 2TmeHfSEXvBaSd415FXsN5asBy+RxRrO/SXnNiJfExZoNAIXrGVa0N8v6NE/ousdsrCr 3n4dpTQ2iU5LkpzBYmKLCGVmeQoxb9l17TpNSliHeer0cPbz5uxE43nmYr2DOxSU21LW 6yKg== X-Gm-Message-State: ACgBeo2TxlljAskRnBfTMDcZHz/OHGRPUvcdjvEYtIzqa+AUsFqkf+p2 xdEhXGvjauBUPY9kXk0AnFNnW2KBCSr9jSvIYT6aunO0t43ZNplEXQ9pfcFeb1ua3csvbIcz0WY UQvfz/LezoUs= X-Received: by 2002:a7b:c003:0:b0:39c:5642:e415 with SMTP id c3-20020a7bc003000000b0039c5642e415mr103193wmb.111.1660076630663; Tue, 09 Aug 2022 13:23:50 -0700 (PDT) X-Google-Smtp-Source: AA6agR5MME3AJynexSREakjc/wtM1ePCr1r4osXSZ1oZmWn8F0r7gEvOHDAhoGVLa2hTVXuiIT2gIQ== X-Received: by 2002:a7b:c003:0:b0:39c:5642:e415 with SMTP id c3-20020a7bc003000000b0039c5642e415mr103178wmb.111.1660076630387; Tue, 09 Aug 2022 13:23:50 -0700 (PDT) Received: from ?IPV6:2003:cb:c705:3700:aed2:a0f8:c270:7f30? (p200300cbc7053700aed2a0f8c2707f30.dip0.t-ipconnect.de. [2003:cb:c705:3700:aed2:a0f8:c270:7f30]) by smtp.gmail.com with ESMTPSA id q11-20020a5d658b000000b0021e4bc9edbfsm11591467wru.112.2022.08.09.13.23.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 09 Aug 2022 13:23:50 -0700 (PDT) Message-ID: <915e2f40-b94a-cef4-7aa7-a402e93dae68@redhat.com> Date: Tue, 9 Aug 2022 22:23:49 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v1] mm/gup: fix FOLL_FORCE COW security issue and remove FOLL_COW To: Linus Torvalds Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org, Andrew Morton , Greg Kroah-Hartman , Axel Rasmussen , Peter Xu , Hugh Dickins , Andrea Arcangeli , Matthew Wilcox , Vlastimil Babka , John Hubbard , Jason Gunthorpe References: <20220808073232.8808-1-david@redhat.com> <91e18a2f-c93d-00b8-7c1b-6d8493c3b2d5@redhat.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1660076636; a=rsa-sha256; cv=none; b=uPzlpSUu7TbMP/UTcykyI1buqm2PZk5Vdao++4hFbztWO7znj2YJR87Y2K46x0BvW7IiYy L4+56XuQv4s8RP0NvP7XolmrRPmLD5Ma/nSoJuvTRzkVjZq5gAvYl5G8kPTtioluBlfLpN Lg2IugtCJ+G2xAZkycK4+jhaUe8o4U4= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=IZ2bYdl4; spf=pass (imf04.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1660076636; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ks5e3vG8/bg6ecSj9dekO7KiLf2ruNOcJnb5Pq8KV1g=; b=TCWoCzXObtQ4XihHIplNOEELXoFIXx+ZPNhnJIDL9XAsMwxNKQtBP9ObCkEv+nbI7oMyd0 MhDPnO+1bQpNPWHIMiecoRXudwK+2hWKMSAW0HUXD+VAyBQp3JjQqGcYbNkG/M2KT2OQRK tiVt1vggPhRuh3VBVLbi/6u1m10lz5w= X-Rspamd-Queue-Id: D8E5440021 Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=IZ2bYdl4; spf=pass (imf04.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: 9kbhx9fpeyiwx5gfjgwq5rx73s599em8 X-HE-Tag: 1660076635-286443 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 09.08.22 22:20, Linus Torvalds wrote: > On Tue, Aug 9, 2022 at 1:14 PM Linus Torvalds > wrote: >> >> But as there are two bits, I'm sure somebody ends up touching one and >> not the other. > > Ugh. The nommu code certainly does odd things here. That just looks wrong. > > And the hugetlb code does something horrible too, but never *sets* it, > so it looks like some odd subset of VM_SHARED. mm/mmap.c:do_mmap() contains the magic bit switch (flags & MAP_TYPE) { case MAP_SHARED: ... case MAP_SHARED_VALIDATE: ... vm_flags |= VM_SHARED | VM_MAYSHARE; if (!(file->f_mode & FMODE_WRITE)) vm_flags &= ~(VM_MAYWRITE | VM_SHARED); fallthrough; VM_SHARED semantics are confusing. -- Thanks, David / dhildenb