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Thu, 23 Apr 2020 20:34:09 -0400 X-MC-Unique: PdLkUA6CP7mzy-z_Ga33bw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 087DD800D24; Fri, 24 Apr 2020 00:34:03 +0000 (UTC) Received: from localhost (ovpn-12-92.pek2.redhat.com [10.72.12.92]) by smtp.corp.redhat.com (Postfix) with ESMTPS id ACFBF1C957; Fri, 24 Apr 2020 00:33:58 +0000 (UTC) Date: Fri, 24 Apr 2020 08:33:56 +0800 From: Baoquan He To: Mike Rapoport Subject: Re: [PATCH 17/21] mm: free_area_init: allow defining max_zone_pfn in descending order Message-ID: <20200424003356.GA10119@MiWiFi-R3L-srv> References: <20200412194859.12663-1-rppt@kernel.org> <20200412194859.12663-18-rppt@kernel.org> <20200423025311.GZ4247@MiWiFi-R3L-srv> <20200423025720.GA4247@MiWiFi-R3L-srv> <20200423055559.GF14260@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200423055559.GF14260@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200423_173416_597803_E9BEA800 X-CRM114-Status: GOOD ( 17.49 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Rich Felker , linux-ia64@vger.kernel.org, linux-doc@vger.kernel.org, Catalin Marinas , Heiko Carstens , Michal Hocko , "James E.J. Bottomley" , Max Filippov , Guo Ren , linux-csky@vger.kernel.org, linux-parisc@vger.kernel.org, sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-riscv@lists.infradead.org, Greg Ungerer , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-c6x-dev@linux-c6x.org, Brian Cain , Jonathan Corbet , linux-sh@vger.kernel.org, Michael Ellerman , Helge Deller , x86@kernel.org, Russell King , Ley Foon Tan , Mike Rapoport , Geert Uytterhoeven , linux-arm-kernel@lists.infradead.org, Mark Salter , Matt Turner , linux-mips@vger.kernel.org, uclinux-h8-devel@lists.sourceforge.jp, linux-xtensa@linux-xtensa.org, linux-alpha@vger.kernel.org, linux-um@lists.infradead.org, linux-m68k@lists.linux-m68k.org, Tony Luck , Greentime Hu , Paul Walmsley , Stafford Horne , Guan Xuetao , Hoan Tran , Michal Simek , Thomas Bogendoerfer , Yoshinori Sato , Nick Hu , linux-mm@kvack.org, Vineet Gupta , linux-kernel@vger.kernel.org, openrisc@lists.librecores.org, Richard Weinberger , Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S. Miller" Sender: "linux-riscv" Errors-To: linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org On 04/23/20 at 08:55am, Mike Rapoport wrote: > On Thu, Apr 23, 2020 at 10:57:20AM +0800, Baoquan He wrote: > > On 04/23/20 at 10:53am, Baoquan He wrote: > > > On 04/12/20 at 10:48pm, Mike Rapoport wrote: > > > > From: Mike Rapoport > > > > > > > > Some architectures (e.g. ARC) have the ZONE_HIGHMEM zone below the > > > > ZONE_NORMAL. Allowing free_area_init() parse max_zone_pfn array even it is > > > > sorted in descending order allows using free_area_init() on such > > > > architectures. > > > > > > > > Add top -> down traversal of max_zone_pfn array in free_area_init() and use > > > > the latter in ARC node/zone initialization. > > > > > > Or maybe leave ARC as is. The change in this patchset doesn't impact > > > ARC's handling about zone initialization, leaving it as is can reduce > > > the complication in implementation of free_area_init(), which is a > > > common function. So I personally don't see a strong motivation to have > > > this patch. > > > > OK, seems this patch is prepared to simplify free_area_init_node(), so > > take back what I said at above. > > > > Then this looks necessary, even though it introduces special case into > > common function free_area_init(). > > The idea is to have a single free_area_init() for all architectures > without keeping two completely different ways of calculating the zone > extents. > Another thing, is that with this we could eventually switch ARC from > DISCONTIGMEM. Yeah, I think uniting them into a single free_area_init() is a great idea. Even though I had been through this patchset, when looked into each of them, still may forget the detail in later patch :)