From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f50.google.com (mail-pa0-f50.google.com [209.85.220.50]) by kanga.kvack.org (Postfix) with ESMTP id 01AB76B0031 for ; Tue, 24 Sep 2013 08:33:46 -0400 (EDT) Received: by mail-pa0-f50.google.com with SMTP id fb1so3645734pad.9 for ; Tue, 24 Sep 2013 05:33:46 -0700 (PDT) Received: by mail-yh0-f41.google.com with SMTP id f73so1923907yha.14 for ; Tue, 24 Sep 2013 05:33:44 -0700 (PDT) Date: Tue, 24 Sep 2013 08:33:40 -0400 From: Tejun Heo Subject: Re: [PATCH 4/6] x86/mem-hotplug: Support initialize page tables bottom up Message-ID: <20130924123340.GE2366@htj.dyndns.org> References: <524162DA.30004@cn.fujitsu.com> <5241649B.3090302@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5241649B.3090302@cn.fujitsu.com> Sender: owner-linux-mm@kvack.org List-ID: To: Zhang Yanfei Cc: "Rafael J . Wysocki" , lenb@kernel.org, Thomas Gleixner , mingo@elte.hu, "H. Peter Anvin" , Andrew Morton , Toshi Kani , Wanpeng Li , Thomas Renninger , Yinghai Lu , Jiang Liu , Wen Congyang , Lai Jiangshan , isimatu.yasuaki@jp.fujitsu.com, izumi.taku@jp.fujitsu.com, Mel Gorman , Minchan Kim , mina86@mina86.com, gong.chen@linux.intel.com, vasilis.liaskovitis@profitbricks.com, lwoodman@redhat.com, Rik van Riel , jweiner@redhat.com, prarit@redhat.com, "x86@kernel.org" , linux-doc@vger.kernel.org, "linux-kernel@vger.kernel.org" , Linux MM , linux-acpi@vger.kernel.org, imtangchen@gmail.com, Zhang Yanfei Hello, On Tue, Sep 24, 2013 at 06:08:27PM +0800, Zhang Yanfei wrote: > +#ifdef CONFIG_MOVABLE_NODE You don't need the above ifdef. The compiler will be able to cull the code as long as memblock_bottom_up() is defined as constant expression when !MOVABLE_NODE. > +/** > + * memory_map_bottom_up - Map [map_start, map_end) bottom up > + * @map_start: start address of the target memory range > + * @map_end: end address of the target memory range > + * > + * This function will setup direct mapping for memory range [map_start, map_end) > + * in a heuristic way. In the beginning, step_size is small. The more memory we > + * map memory in the next loop. The same comment as before. Now we have two function with the identical comment but behaving differently, which isn't nice. ... > + * If the allocation is in bottom-up direction, we start from the > + * bottom and go to the top: first [kernel_end, end) and then > + * [ISA_END_ADDRESS, kernel_end). Otherwise, we start from the top > + * (end of memory) and go to the bottom. > + * > + * The memblock_find_in_range() gets us a block of RAM in > + * [min_pfn_mapped, max_pfn_mapped) used as new pages for page table. > */ > - memory_map_top_down(ISA_END_ADDRESS, end); > + if (memblock_bottom_up()) { > + unsigned long kernel_end; > + > + kernel_end = round_up(__pa_symbol(_end), PMD_SIZE); > + memory_map_bottom_up(kernel_end, end); > + memory_map_bottom_up(ISA_END_ADDRESS, kernel_end); Hmm... so, this is kinda weird. We're doing it in two chunks and mapping memory between ISA_END_ADDRESS and kernel_end right on top of ISA_END_ADDRESS? Can't you give enough information to the mapping function so that it can map everything on top of kernel_end in single go? Thanks. -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org