From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 24 Apr 2020 08:33:56 +0800 From: Baoquan He 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> To: Mike Rapoport Cc: linux-kernel@vger.kernel.org, Andrew Morton , Brian Cain , Catalin Marinas , "David S. Miller" , Geert Uytterhoeven , Greentime Hu , Greg Ungerer , Guan Xuetao , Guo Ren , Heiko Carstens , Helge Deller , Hoan Tran , "James E.J. Bottomley" , Jonathan Corbet , Ley Foon Tan , Mark Salter , Matt Turner , Max Filippov , Michael Ellerman , Michal Hocko , Michal Simek , Nick Hu , Paul Walmsley , Richard Weinberger , Rich Felker , Russell King , Stafford Horne , Thomas Bogendoerfer , Tony Luck , Vineet Gupta , x86@kernel.org, Yoshinori Sato , linux-alpha@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-c6x-dev@linux-c6x.org, linux-csky@vger.kernel.org, linux-doc@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org, openrisc@lists.librecores.org, sparclinux@vger.kernel.org, uclinux-h8-devel@lists.sourceforge.jp, Mike Rapoport List-ID: 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 :)