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 A84F64B487B; Tue, 8 Sep 2026 20:35:11 +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=1788899712; cv=none; b=HXXEGOgM74OhrUyTLtsesdYhwpmsocmM4wtVNV8ygdmc/To6UMltYFvBFDRmh5QL+GpEfaEO6+B40LEjltT46iXOIGhWHe+EpyM5A4FNoXgwXOt4jVSBnEwAkjBoDCTlojwwg96IGnZ4dvDoQRnM6ZAwJUiIospFwfl2bx7jbb8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788899712; c=relaxed/simple; bh=0EObSyqjpYUAi3FP29etQ+gO9bJfv428SfaAmw7F/yk=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=eBO2FmTGzkXXcXmcgupBCzXenOsR/Z8BgdnuhIEKD6NPXUP2PJrOpyYyZ3G+xPesTLw7vQcapm8arUgVFu0hxzy4tzLTX6U00IDsdRWe9ASSgLUyni0Av7PgQitkGYpIO/PEsY0WhgXteNS+KxBw8jlNI+2tnxkWgP0Lc6d8Zmg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LmzhJDlZ; 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="LmzhJDlZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 777D11F00A3A; Tue, 8 Sep 2026 20:35:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788899711; bh=0EObSyqjpYUAi3FP29etQ+gO9bJfv428SfaAmw7F/yk=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=LmzhJDlZx8UFG2B1LZdno3eFU5ps1kiAK2rdCGGLK/6d+bKqwU/K0bIbxm5nZdcqo 64KIpYX9h0tHaOKG2qCOWV1nT+IcTEddix2K/6ngbxYs8pLuCIW+3kV7cYrTNU4LjL rT+BBK5hbycWQeH4mpCgHNh05Cg6r3Kzvkpzh+YneN+erQptLBRDWPP32esNyiAckX fnLoR/IkQgL8biceIKkgg4LZyAXJId4jo/LO8rpqHSKgG7LJZcCwtSArA9JyThBK4u 8x+Qz8WMMIsOBCeL99KoBWJjFxDBSCfJ5xLxNtXUphCIqOFXBp4uwdR5hFBOa/hf69 MocWq7m7NuQjw== From: sashiko-bot@kernel.org Subject: Re: [PATCH 09/39] drivers/usb/mon: update to use mmap_prepare + map kernel pages Reply-To: sashiko-reviews@lists.linux.dev To: =?utf-8?b?TG9yZW56byBTdG9ha2VzIChBUk0p?= Cc: selinux@vger.kernel.org, bpf@vger.kernel.org, linux-s390@vger.kernel.org, linux-perf-users@vger.kernel.org, "Alexander Gordeev" , kvmarm@lists.linux.dev, "Marc Zyngier" , kvm@vger.kernel.org, "Heiko Carstens" , "Vasily Gorbik" , linux-trace-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, "Christian Borntraeger" , dri-devel@lists.freedesktop.org, "Oliver Upton" In-Reply-To: <20260908-b4-mmap-prepare-vma-flag-sanify-v1-9-dacf19cce22b@kernel.org> References: <20260908-b4-mmap-prepare-vma-flag-sanify-v1-0-dacf19cce22b@kernel.org> <20260908-b4-mmap-prepare-vma-flag-sanify-v1-9-dacf19cce22b@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 08 Sep 2026 20:35:10 +0000 Message-Id: <20260908203510.777D11F00A3A@smtp.kernel.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: > Replace the deprecated .mmap hook with its replacement .mmap_prepare. As > part of this change, additionally take the approach of mapping pages upon > mmap rather than providing a fault handler. >=20 > The page span cannot be mutated when an mmap mapping is in place, so this > is safe to do in advance (the MON_IOCT_RING_SIZE ioctl operation exits > -EBUSY if it's attempted, gated by the rp->mmap_active reference count). >=20 > Utilise the newly introduced mmap_action_map_discontig_kernel_pages() to = do > this, which allows for iteration over pages in mon_bin_discontig_get(). >=20 > mon_bin_discontig_init() increments the rp->mmap_active reference count to > stabilise page spans. Should an error arise the core unmaps the VMA and > mon_bin_vma_close() drops the reference again. >=20 > [ ... ] > One behavioural difference: pages are no longer faulted in on demand, so a > page discarded with MADV_DONTNEED is not repopulated and a subsequent > access raises SIGBUS, as with other pre-populated kernel mappings. >=20 > 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/20260908-b4-mmap-pr= epare-vma-flag-sanify-v1-0-dacf19cce22b@kernel.org?part=3D9