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=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 C809AC43381 for ; Thu, 4 Mar 2021 14:19:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A514D64F23 for ; Thu, 4 Mar 2021 14:19:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241814AbhCDOS2 (ORCPT ); Thu, 4 Mar 2021 09:18:28 -0500 Received: from mail.kernel.org ([198.145.29.99]:42402 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241785AbhCDOSR (ORCPT ); Thu, 4 Mar 2021 09:18:17 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 38AC164EF6; Thu, 4 Mar 2021 14:17:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614867456; bh=5SFoOpkNOISja2bka7WY1xY3Xu6DHtOUpfvK1KKO0Ho=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KmSdKQPpfL8NUZTjBgr8+DvFEaxjKTvLNf2mi07XjFMqkkhK2Wdm0PdGbpJ1Ml5uQ dnNvPSaNnj9YiUrkr3hPxBKjrOs8rA1yvnUUv3ONmKgy5v87x3AASqOgqtnN02pDa2 z1hwXqWqpgjmYJN7O8sM35kkT/bZypmcKNvWHPqk= Date: Thu, 4 Mar 2021 15:17:34 +0100 From: Greg KH To: Nicolas Saenz Julienne Cc: Jing Xiangfeng , 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 Subject: Re: [PATCH stable v5.10 0/7] arm64: Default to 32-bit wide ZONE_DMA Message-ID: References: <20210303073319.2215839-1-jingxiangfeng@huawei.com> <9bc396116372de5b538d71d8f9ae9c3259f1002e.camel@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9bc396116372de5b538d71d8f9ae9c3259f1002e.camel@suse.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 04, 2021 at 03:05:32PM +0100, Nicolas Saenz Julienne wrote: > 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. > > > > 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 memory > and ZONE_DMA32 the rest of the 32bit address space. Since you can't allocate > memory that crosses zone boundaries, this broke crashkernel allocations on big > machines. This series fixes all this by parsing the HW description and checking > for DMA constrained buses. When not found, the unnecessary zone creation is > skipped. What kernel/commit caused this "breakage"? thanks, greg k-h