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=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,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 EC682C433E9 for ; Thu, 4 Mar 2021 14:07:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B3E3364F39 for ; Thu, 4 Mar 2021 14:07:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239461AbhCDOGo (ORCPT ); Thu, 4 Mar 2021 09:06:44 -0500 Received: from mx2.suse.de ([195.135.220.15]:53812 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237908AbhCDOGQ (ORCPT ); Thu, 4 Mar 2021 09:06:16 -0500 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 E1DFBAAC5; Thu, 4 Mar 2021 14:05:34 +0000 (UTC) Message-ID: <9bc396116372de5b538d71d8f9ae9c3259f1002e.camel@suse.de> Subject: Re: [PATCH stable v5.10 0/7] arm64: Default to 32-bit wide ZONE_DMA From: Nicolas Saenz Julienne To: Greg KH , Jing Xiangfeng Cc: catalin.marinas@arm.com, will@kernel.org, akpm@linux-foundation.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, rppt@kernel.org, lorenzo.pieralisi@arm.com, guohanjun@huawei.com, sudeep.holla@arm.com, rjw@rjwysocki.net, lenb@kernel.org, song.bao.hua@hisilicon.com, ardb@kernel.org, anshuman.khandual@arm.com, bhelgaas@google.com, guro@fb.com, robh+dt@kernel.org, stable@vger.kernel.org, linux-arm-kernel@lists.infradead.org, frowand.list@gmail.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, wangkefeng.wang@huawei.com Date: Thu, 04 Mar 2021 15:05:32 +0100 In-Reply-To: References: <20210303073319.2215839-1-jingxiangfeng@huawei.com> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-ahu+lDeVyw/D0YYfX8dU" User-Agent: Evolution 3.38.4 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-ahu+lDeVyw/D0YYfX8dU Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi Greg. On Thu, 2021-03-04 at 14:46 +0100, Greg KH wrote: > On Wed, Mar 03, 2021 at 03:33:12PM +0800, Jing Xiangfeng wrote: > > Using two distinct DMA zones turned out to be problematic. Here's an > > attempt go back to a saner default. >=20 > What problem does this solve? How does this fit into the stable kernel > rules? We changed the way we setup memory zones in arm64 in order to cater for Raspberry Pi 4's weird DMA constraints: ZONE_DMA spans the lower 1GB of mem= ory and ZONE_DMA32 the rest of the 32bit address space. Since you can't allocat= e memory that crosses zone boundaries, this broke crashkernel allocations on = big machines. This series fixes all this by parsing the HW description and chec= king for DMA constrained buses. When not found, the unnecessary zone creation is skipped. That said, I have no clue whether this falls or not into the stable kernel rules. Regards, Nicolas --=-ahu+lDeVyw/D0YYfX8dU 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/4FAmBA6SwACgkQlfZmHno8 x/63Hwf/dPKsaiMfp4bHs98aLzm1BcfLltFqLOj2tjBqOYX6mUdfSKOkKZYGvyTs zZo2tT5ezbzEvU69CHgGmb6u3y4Q6PxDKqoL94xC+7RGwDrw4g4o0TZp67pcA/9d fUjl00sLvQUl6YYcajb6s0Ev97pb3XAyvAozXb3hfz36j/30mKbizfnxhn9gTZD0 lJ6Kp8Bmm0/weVW4Kj/SOnBk0J2WF7IwSxbJMKRz8k2ejAytoILh4PZ24V9c58Jw qhATgehwhDXk7hyZYQAKCr3pQD9fjWVVjU4/vbWXqBFvUhdmDSkCRAfYwZLJA1Cw lRRAL3P3GOOnCmGp7VZpexw14txF9Q== =1f1V -----END PGP SIGNATURE----- --=-ahu+lDeVyw/D0YYfX8dU--