Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759457Ab3HOSEO (ORCPT ); Thu, 15 Aug 2013 14:04:14 -0400 Received: from mga02.intel.com ([134.134.136.20]:48460 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753382Ab3HOSEN (ORCPT ); Thu, 15 Aug 2013 14:04:13 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.89,886,1367996400"; d="scan'208";a="387730945" Message-ID: <520D1806.5040309@intel.com> Date: Thu, 15 Aug 2013 11:03:50 -0700 From: Dave Hansen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130803 Thunderbird/17.0.8 MIME-Version: 1.0 To: Wanpeng Li CC: Andrew Morton , Rik van Riel , Dave Hansen , Fengguang Wu , Joonsoo Kim , Johannes Weiner , Tejun Heo , Yasuaki Ishimatsu , David Rientjes , KOSAKI Motohiro , Jiri Kosina , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] mm/sparse: introduce alloc_usemap_and_memmap References: <1376526703-2081-1-git-send-email-liwanp@linux.vnet.ibm.com> <1376526703-2081-2-git-send-email-liwanp@linux.vnet.ibm.com> In-Reply-To: <1376526703-2081-2-git-send-email-liwanp@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2313 Lines: 65 On 08/14/2013 05:31 PM, Wanpeng Li wrote: > After commit 9bdac91424075("sparsemem: Put mem map for one node together."), > vmemmap for one node will be allocated together, its logic is similiar as > memory allocation for pageblock flags. This patch introduce alloc_usemap_and_memmap > to extract the same logic of memory alloction for pageblock flags and vmemmap. Shame on whoever copy-n-pasted that in the first place. > - > - for (pnum = 0; pnum < NR_MEM_SECTIONS; pnum++) { > - struct mem_section *ms; > - > - if (!present_section_nr(pnum)) > - continue; > - ms = __nr_to_section(pnum); > - nodeid_begin = sparse_early_nid(ms); > - pnum_begin = pnum; > - break; > - } > - usemap_count = 1; > - for (pnum = pnum_begin + 1; pnum < NR_MEM_SECTIONS; pnum++) { > - struct mem_section *ms; > - int nodeid; > - > - if (!present_section_nr(pnum)) > - continue; > - ms = __nr_to_section(pnum); > - nodeid = sparse_early_nid(ms); > - if (nodeid == nodeid_begin) { > - usemap_count++; > - continue; > - } > - /* ok, we need to take cake of from pnum_begin to pnum - 1*/ > - sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, pnum, > - usemap_count, nodeid_begin); > - /* new start, update count etc*/ > - nodeid_begin = nodeid; > - pnum_begin = pnum; > - usemap_count = 1; > - } > - /* ok, last chunk */ > - sparse_early_usemaps_alloc_node(usemap_map, pnum_begin, NR_MEM_SECTIONS, > - usemap_count, nodeid_begin); > + alloc_usemap_and_memmap(usemap_map, true); ... > + alloc_usemap_and_memmap((unsigned long **)map_map, false); > #endif Why does alloc_usemap_and_memmap() take an 'unsigned long **'? 'unsigned long' is for the usemap and 'struct page' is for the memmap. It's misleading to have it take an 'unsigned long **' and then just cast it over to a 'struct page **' internally. Also, what's the point of having a function that returns something in a double-pointer, but that doesn't use its return value? alloc_usemap_and_memmap() also needs a comment about what it's doing with that pointer and its other argument. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/