From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BF9214F3EC0; Fri, 9 Oct 2026 18:25:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791570340; cv=none; b=rgMekyDbwKBpDNZmPVCJO150OrcZc66FEiEYBn/xGK/Zz0z8Y3ycG5iLoKnbtvoIrl+AK/Gdkgomb8gS0XWITmL6ZbiS+R2HqEntafHeh4mB6FZ1VAgsoF6cKitFxb+HuZaakQmYHWHkCXptIJFYMwuJjyniFpYG+GGVaJd1bFA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791570340; c=relaxed/simple; bh=MK7Nr2Nu7uvhQn31gvJdVwUygXMsiFq2UzEOYgc5v2w=; h=Message-ID:From:Subject:To:Cc:In-Reply-To:References:Content-Type: Date; b=vFCn+SpBsrqhazRAoeN+V/ewKoayi2fvYiImLl4rEknOI+1naQWpezzmevQWy2sg8rwYLHf3Xqp7tFMAs522VbeX0lBWtf9QFJ0wrdz7OamhSVTrXZf4DDrpjIAaOIWEgig8WKZfexa1Q6smTWsWK3yJtqBV8o6+0/8+3XoOSLU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MrSmUbNc; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MrSmUbNc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 912E61F000FF; Fri, 9 Oct 2026 18:25:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791570339; bh=MK7Nr2Nu7uvhQn31gvJdVwUygXMsiFq2UzEOYgc5v2w=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=MrSmUbNcQHbTnB89UHYRAjVu6CmoeldVEIyixJx8+kLiVxlBDw/wNHZP7cTJ420PW Rs4mZ9xpkxGWFBPmun0PvJkmc9/Gq+Da5OFDw0Ryv0OVRZjInTEQ9XTxVuz8WmmMBO NVTO/4AZZIjMrCaCdmJD6iLUPLv/BrlkWqqfYr70BZduAwqXQpTd2M6zD84iCyk+BM asriG8bekDwJp0jBg/3kUizUb33UvKseso6yel9/BoO9c9BXBbfIrz6qLNNRKwl8nU 8x0v2t4WmSF5NtltNNTDchpDbKMpRgPt2rPJbr1NombtPrOilnexI5YvK4EzKAckt+ roOAyMZ7VyKuQ== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v5 15/38] mm/vma: only allow mmap to clear VMA_MAYWRITE_BIT if not mm-managed Reply-To: sashiko-reviews@lists.linux.dev To: =?utf-8?b?TG9yZW56byBTdG9ha2VzIChBUk0p?= Cc: bpf@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-usb@vger.kernel.org, "Marc Zyngier" , "Christian Borntraeger" , linux-trace-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, "Vasily Gorbik" , linux-rdma@vger.kernel.org, "Alexander Gordeev" , "Oliver Upton" , linux-perf-users@vger.kernel.org, selinux@vger.kernel.org, "Heiko Carstens" , kvmarm@lists.linux.dev, linux-scsi@vger.kernel.org In-Reply-To: <20261009-b4-mmap-prepare-vma-flag-sanify-v5-15-923b70125b1e@kernel.org> References: <20261009-b4-mmap-prepare-vma-flag-sanify-v5-0-923b70125b1e@kernel.org> <20261009-b4-mmap-prepare-vma-flag-sanify-v5-15-923b70125b1e@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Fri, 09 Oct 2026 18:25:38 +0000 Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: > For ordinary files the only way the VMA_MAYWRITE_BIT flag is cleared is if > the underlying file is itself read-only. >=20 > This means that mprotect() cannot mark a shared mapping of a read-only fi= le > as read/write, as doing so would violate the read only attribute, and > permit writes. >=20 > In general, we do not want file systems to be able to do this for > read/write files. >=20 > Doing so would violate fundamental user expectation of file attributes and > likely break userspace. >=20 > However, drivers pose a tricky problem here - the /dev/xxx file may be > read/write but provide access to a resource which is fundamentally > [ ... ] > As no driver which clears VMA_MAYWRITE_BIT establishes an mm-managed > mapping, no functional change is intended. >=20 > Acked-by: Zi Yan > Signed-off-by: Lorenzo Stoakes (ARM) Sashiko has reviewed this patch and found no issues. It looks great! --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261009-b4-mmap-pr= epare-vma-flag-sanify-v5-0-923b70125b1e@kernel.org?part=3D15