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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 AE8C1C433E0 for ; Fri, 10 Jul 2020 08:20:11 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 841D0206A5 for ; Fri, 10 Jul 2020 08:20:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 841D0206A5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 4F40E88310; Fri, 10 Jul 2020 08:20:11 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id uxsjiskLQzvv; Fri, 10 Jul 2020 08:20:10 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by whitealder.osuosl.org (Postfix) with ESMTP id AE8E6882FD; Fri, 10 Jul 2020 08:20:10 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 9D2C0C016F; Fri, 10 Jul 2020 08:20:10 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id D7FDCC0865 for ; Fri, 10 Jul 2020 08:20:08 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 5042C89666 for ; Fri, 10 Jul 2020 08:19:46 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id DpwwM4MNqsrk for ; Fri, 10 Jul 2020 08:19:45 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by whitealder.osuosl.org (Postfix) with ESMTPS id BF5A789660 for ; Fri, 10 Jul 2020 08:19:44 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id AFBB7AB7A; Fri, 10 Jul 2020 08:19:42 +0000 (UTC) Message-ID: <5c21867fd2e9c1c25f3080deeeb0ccdb3070ead2.camel@suse.de> Subject: Re: [PATCH] dma-pool: use single atomic pool for both DMA zones From: Nicolas Saenz Julienne To: David Rientjes , Christoph Hellwig Date: Fri, 10 Jul 2020 10:19:40 +0200 In-Reply-To: References: <20200707122804.21262-1-nsaenzjulienne@suse.de> <20200708153509.GA26743@lst.de> <20200708161010.GA30184@lst.de> User-Agent: Evolution 3.36.3 MIME-Version: 1.0 Cc: linux-kernel@vger.kernel.org, jeremy.linton@arm.com, iommu@lists.linux-foundation.org, linux-rpi-kernel@lists.infradead.org, Robin Murphy X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============0048570396864706301==" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" --===============0048570396864706301== Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-ghHFpb3jrVR40NR7F7FC" --=-ghHFpb3jrVR40NR7F7FC Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2020-07-09 at 14:49 -0700, David Rientjes wrote: > On Wed, 8 Jul 2020, Christoph Hellwig wrote: >=20 > > On Wed, Jul 08, 2020 at 06:00:35PM +0200, Nicolas Saenz Julienne wrote: > > > On Wed, 2020-07-08 at 17:35 +0200, Christoph Hellwig wrote: > > > > On Tue, Jul 07, 2020 at 02:28:04PM +0200, Nicolas Saenz Julienne wr= ote: > > > > > When allocating atomic DMA memory for a device, the dma-pool core > > > > > queries __dma_direct_optimal_gfp_mask() to check which atomic poo= l to > > > > > use. It turns out the GFP flag returned is only an optimistic gue= ss. > > > > > The pool selected might sometimes live in a zone higher than the > > > > > device's view of memory. > > > > >=20 > > > > > As there isn't a way to grantee a mapping between a device's DMA > > > > > constraints and correct GFP flags this unifies both DMA atomic po= ols. > > > > > The resulting pool is allocated in the lower DMA zone available, = if > > > > > any, > > > > > so as for devices to always get accessible memory while having th= e > > > > > flexibility of using dma_pool_kernel for the non constrained ones= . > > > > >=20 > > > > > Fixes: c84dc6e68a1d ("dma-pool: add additional coherent pools to = map > > > > > to gfp > > > > > mask") > > > > > Reported-by: Jeremy Linton > > > > > Suggested-by: Robin Murphy > > > > > Signed-off-by: Nicolas Saenz Julienne > > > >=20 > > > > Hmm, this is not what I expected from the previous thread. I thoug= ht > > > > we'd just use one dma pool based on runtime available of the zones.= . > > >=20 > > > I may be misunderstanding you, but isn't that going back to how thing= s > > > used to > > > be before pulling in David Rientjes' work? The benefit of having a > > > GFP_KERNEL > > > pool is that non-address-constrained devices can get their atomic mem= ory > > > there, > > > instead of consuming somewhat scarcer low memory. > >=20 > > Yes, I think we are misunderstanding each other. I don't want to remov= e > > any pool, just make better runtime decisions when to use them. > >=20 >=20 > Just to be extra explicit for the record and for my own understanding:= =20 > Nicolas, your patch series "dma-pool: Fix atomic pool selection" obsolete= s=20 > this patch, right? :) Yes, that's right. Regards, Nicolas --=-ghHFpb3jrVR40NR7F7FC 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/4FAl8IJJwACgkQlfZmHno8 x/7eRgf+LVqWrnAjb1c88gXOrDMdl27HUQzIDYXit5TQgnkyp7CwzALmvSEnc2Es BtY2vTG+MkAnQosY5mRuw2Ycs6K89qFjVnd5JmCefM44A89n3vTG1Fu3/1yOFjEZ dcdJuY7x6pFvZal7dEJpm3BMjWMGPRwCgdgF3fMmVqfwA7k4R0TflEZT/W7fSz1N c9mVgO4dfv4uBghkHYe+ffZ/71uuWtebNkM5mwygsTJ6IFvQErnf0jF4ROi+Tv+o XvKnWsFxvX8B36eZWhNHr5bWXbS7dHjAqiwIqhgKvwRvEqrSWVL3np29KwdrP09k 4AowWeWsNLJ9kHsHfaoaubpv6nUDbA== =ZWwI -----END PGP SIGNATURE----- --=-ghHFpb3jrVR40NR7F7FC-- --===============0048570396864706301== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu --===============0048570396864706301==--