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 A0FE83A7D98; Sat, 3 Oct 2026 17:56:50 +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=1791050212; cv=none; b=I8cVH3uwP+esubtZwJBdp/fZELteTCubSs+xeDz9KDt2bkzMy+4oAyUZguPqRo6/n9+84A6cbc2/MyhiM7b9ibZazovWYKIpxb8KaDSfdJuQ4KDdWk9SbPtr9oEeBUqXIzzeoZdhPUv4XsIALD4a9b6gVfoRBwo32+ySMhp0Vjk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791050212; c=relaxed/simple; bh=iSVlcTDDIwilpTIFpoJd4dbbYhXAYFyiKbuOnRJzCTQ=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=W6YxGXcxIbhuN4c88XF8TNqmM+2jxb+FVeO++pifq/FAa8g8zrJ1+AHUs5j8kiAFPDZlaV3Ll7airkaAjchzMuPmHKG7Vm1G/8Q2AxfIXZhJ5+6SmULAQmUyPASqGTuNlvdu0nl2oc4LaUuYmZRaKhp9hbVeuepPt7bhqn80P+c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=S8UjPvb0; 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="S8UjPvb0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8D0B91F008A0; Sat, 3 Oct 2026 17:56:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791050210; bh=iSVlcTDDIwilpTIFpoJd4dbbYhXAYFyiKbuOnRJzCTQ=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=S8UjPvb0uyFG2SIoLBKdnmLEppjDvwQsuoJsiNJiUqsrrcscO12yTa4/DeE0YGwqi RDHTsjecBuoyJ5d077/IiCui0EJTgMoXaJeW7Y+wz+3CEuGblujSmDoOXtDAGEtCiG XO6eEv+lpSNmJi7eL7T6ws1e3nc/+/zKJ+RaKpaQ6n3SquTCjaABkT77gKDOdRM1Lb NL6uNd5gsYBDXwFHyuBaZ2/+8opsCOj7jxdLmterkVLfM/R+aLlwUMDLKTlP6A7x6j fQH816Lye5Ud//q63qAFBBIQPQrM2RCXaRUQOICZubydjeDVVOXVRB1KMgBOqlySYQ 0J3FhibLulEWw== From: sashiko-bot@kernel.org Subject: Re: [PATCH v4 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: linux-s390@vger.kernel.org, bpf@vger.kernel.org, linux-rdma@vger.kernel.org, "Vasily Gorbik" , selinux@vger.kernel.org, "Alexander Gordeev" , linux-perf-users@vger.kernel.org, linux-scsi@vger.kernel.org, kvm@vger.kernel.org, "Marc Zyngier" , kvmarm@lists.linux.dev, "Christian Borntraeger" , "Oliver Upton" , linux-trace-kernel@vger.kernel.org, "Heiko Carstens" , dri-devel@lists.freedesktop.org In-Reply-To: <20261003-b4-mmap-prepare-vma-flag-sanify-v4-15-a1f052500fd7@kernel.org> References: <20261003-b4-mmap-prepare-vma-flag-sanify-v4-0-a1f052500fd7@kernel.org> <20261003-b4-mmap-prepare-vma-flag-sanify-v4-15-a1f052500fd7@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Sat, 03 Oct 2026 17:56:49 +0000 Message-Id: <20261003175649.8D0B91F008A0@smtp.kernel.org> Precedence: bulk X-Mailing-List: kvm@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/20261003-b4-mmap-pr= epare-vma-flag-sanify-v4-0-a1f052500fd7@kernel.org?part=3D15