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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2857C433FF for ; Thu, 1 Aug 2019 16:41:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D38E02087E for ; Thu, 1 Aug 2019 16:41:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733098AbfHAQlL (ORCPT ); Thu, 1 Aug 2019 12:41:11 -0400 Received: from mx2.suse.de ([195.135.220.15]:59518 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1732035AbfHAQlK (ORCPT ); Thu, 1 Aug 2019 12:41:10 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id E44E3AFA1; Thu, 1 Aug 2019 16:41:07 +0000 (UTC) Message-ID: <4027201b6128b3f2b0ab941dc473ab143da64be2.camel@suse.de> Subject: Re: [PATCH 5/8] arm64: use ZONE_DMA on DMA addressing limited devices From: Nicolas Saenz Julienne To: Robin Murphy , Catalin Marinas Cc: phill@raspberryi.org, devicetree@vger.kernel.org, f.fainelli@gmail.com, linux-mm@kvack.org, marc.zyngier@arm.com, Will Deacon , linux-kernel@vger.kernel.org, eric@anholt.net, iommu@lists.linux-foundation.org, robh+dt@kernel.org, linux-rpi-kernel@lists.infradead.org, mbrugger@suse.com, akpm@linux-foundation.org, m.szyprowski@samsung.com, frowand.list@gmail.com, hch@lst.de, linux-arm-kernel@lists.infradead.org, wahrenst@gmx.net Date: Thu, 01 Aug 2019 18:40:50 +0200 In-Reply-To: References: <20190731154752.16557-1-nsaenzjulienne@suse.de> <20190731154752.16557-6-nsaenzjulienne@suse.de> <20190731170742.GC17773@arrakis.emea.arm.com> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-qAJVJtco/gH4l0Ax6g8O" User-Agent: Evolution 3.32.4 MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-qAJVJtco/gH4l0Ax6g8O Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2019-08-01 at 17:07 +0100, Robin Murphy wrote: > On 2019-08-01 4:44 pm, Nicolas Saenz Julienne wrote: > > On Wed, 2019-07-31 at 18:07 +0100, Catalin Marinas wrote: > > > On Wed, Jul 31, 2019 at 05:47:48PM +0200, Nicolas Saenz Julienne wrot= e: > > > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > > > > index 1c4ffabbe1cb..f5279ef85756 100644 > > > > --- a/arch/arm64/mm/init.c > > > > +++ b/arch/arm64/mm/init.c > > > > @@ -50,6 +50,13 @@ > > > > s64 memstart_addr __ro_after_init =3D -1; > > > > EXPORT_SYMBOL(memstart_addr); > > > > =20 > > > > +/* > > > > + * We might create both a ZONE_DMA and ZONE_DMA32. ZONE_DMA is nee= ded > > > > if > > > > there > > > > + * are periferals unable to address the first naturally aligned 4G= B of > > > > ram. > > > > + * ZONE_DMA32 will be expanded to cover the rest of that memory. I= f > > > > such > > > > + * limitations doesn't exist only ZONE_DMA32 is created. > > > > + */ > > >=20 > > > Shouldn't we instead only create ZONE_DMA to cover the whole 32-bit > > > range and leave ZONE_DMA32 empty? Can__GFP_DMA allocations fall back > > > onto ZONE_DMA32? > >=20 > > Hi Catalin, thanks for the review. > >=20 > > You're right, the GFP_DMA page allocation will fail with a nasty dmesg = error > > if > > ZONE_DMA is configured but empty. Unsurprisingly the opposite situation= is > > fine > > (GFP_DMA32 with an empty ZONE_DMA32). >=20 > Was that tested on something other than RPi4 with more than 4GB of RAM?= =20 > (i.e. with a non-empty ZONE_NORMAL either way) No, all I did is play around with RPi4's memory size (1 GB vs 4 GB). I'll see If I can get access to a dts based board with more than 4 GB, If n= ot I'll try to fake it. It's not ideal but I can set the limit on 3 GB and hav= e the 3 areas created (with and witouth an empty ZONE_DMA32). On top of that, now that you ask, I realise I neglected all the ACPI based servers. I have access to some so I'll make sure I test everything on them = too for the next series. Regards, Nicolas --=-qAJVJtco/gH4l0Ax6g8O Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEErOkkGDHCg2EbPcGjlfZmHno8x/4FAl1DFhIACgkQlfZmHno8 x/5YnAf/aih3gNCdpPnk9CDn+WHuChefMegomFiKPy7KLWGYmB9OrtzlXlYit3VU z2zffpz7+B+tFBZWLyxyQfJ8sT8uogFFJR+HNsvucEC2z4cDMksEkCgYQRHcv5iq 4CDSPUrd5zuESxZjq3ne7sLGx0G41aVs7o+iKAaUls/WAhq7MbYiq8B/r9HPnS1/ qAxsHlnX0PASFIN3BCnr+1VSy+xbwpFNSNVfqLYtWRQZvI8ww3Epx/AbWcTKy3YC 3YbXITPMlA4Mf+0ROrmU4sf0dj/mdQkC6SYqPjTMqVYyzON4rJ/MvOChQDmEGPs6 WiNr9ZnC1GXA4QfwFXcRrfK85+Y0vw== =e240 -----END PGP SIGNATURE----- --=-qAJVJtco/gH4l0Ax6g8O--