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[209.85.221.52]) by smtp.gmail.com with ESMTPSA id me25-20020a170906aed900b007317f017e64sm1484591ejb.134.2022.08.09.13.20.52 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 09 Aug 2022 13:20:52 -0700 (PDT) Received: by mail-wr1-f52.google.com with SMTP id j1so15565070wrw.1 for ; Tue, 09 Aug 2022 13:20:52 -0700 (PDT) X-Received: by 2002:a5d:6248:0:b0:222:cd3b:94c8 with SMTP id m8-20020a5d6248000000b00222cd3b94c8mr7137394wrv.97.1660076452117; Tue, 09 Aug 2022 13:20:52 -0700 (PDT) MIME-Version: 1.0 References: <20220808073232.8808-1-david@redhat.com> <91e18a2f-c93d-00b8-7c1b-6d8493c3b2d5@redhat.com> In-Reply-To: From: Linus Torvalds Date: Tue, 9 Aug 2022 13:20:36 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v1] mm/gup: fix FOLL_FORCE COW security issue and remove FOLL_COW To: David Hildenbrand 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 Content-Type: text/plain; charset="UTF-8" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1660076455; a=rsa-sha256; cv=none; b=tCVroW5Lf29jXBAqi1WJfqUOjjMetgjV3R6FxcvrmVkXc9YtQ2VCI1aZmJJ/eviNXvql2/ gu2Jkh3jc5Vny7ogcsEUAwS92ZmclQu/gdSEQrjusLoPeroMSQlnP0EzJsVeUwfrJkHHMg ElezWLLil0sNTfnyEtsTUg5x0JFvN/U= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=WEfpeEZL; dmarc=none; spf=pass (imf13.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.218.43 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1660076455; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=DGKHHAUwuZfCazjxcNKKHUT7rJIi8ll9zTOb4y7hCUc=; b=rgdPtOWuaAIDaWQWTAEUxtGAEoSs5jBi/wXPJ/mX6ZcQ1KxM6MByBFdexqsgykffeGu5Ap yq/z8dXxiBRX9geZjiBZE2kbIgyhRW9KNS1OSZjNIdPdvQk+7VLx3fmTURAwotB8PH08Yq Mum2yk/O6QR6IoOO1PijbM+IJ4/Ihgk= X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 02D482005C Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=google header.b=WEfpeEZL; dmarc=none; spf=pass (imf13.hostedemail.com: domain of torvalds@linuxfoundation.org designates 209.85.218.43 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org X-Rspam-User: X-Stat-Signature: jquaje8k5k951jxkfefhj3uy4g4muu46 X-HE-Tag: 1660076454-512278 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 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. Linus