Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752725Ab0GNA1z (ORCPT ); Tue, 13 Jul 2010 20:27:55 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:51634 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751515Ab0GNA1x (ORCPT ); Tue, 13 Jul 2010 20:27:53 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Wed, 14 Jul 2010 09:23:01 +0900 From: KAMEZAWA Hiroyuki To: Minchan Kim Cc: Dave Hansen , Johannes Weiner , linux@arm.linux.org.uk, Yinghai Lu , "H. Peter Anvin" , Andrew Morton , Shaohua Li , Yakui Zhao , linux-kernel@vger.kernel.org, linux-mm@kvack.org, arm-kernel@lists.infradead.org, kgene.kim@samsung.com, Mel Gorman Subject: Re: [RFC] Tight check of pfn_valid on sparsemem Message-Id: <20100714092301.69e7e628.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100713164423.GC2815@barrios-desktop> References: <20100712155348.GA2815@barrios-desktop> <20100713093006.GB14504@cmpxchg.org> <20100713154335.GB2815@barrios-desktop> <1279038933.10995.9.camel@nimitz> <20100713164423.GC2815@barrios-desktop> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 3.0.3 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4849 Lines: 147 On Wed, 14 Jul 2010 01:44:23 +0900 Minchan Kim wrote: > > If you _really_ can't make the section size smaller, and the vast > > majority of the sections are fully populated, you could hack something > > in. We could, for instance, have a global list that's mostly readonly > > which tells you which sections need to be have their sizes closely > > inspected. That would work OK if, for instance, you only needed to > > check a couple of memory sections in the system. It'll start to suck if > > you made the lists very long. > > Thanks for advise. As I say, I hope Russell accept 16M section. > It seems what I needed was good sleep.... How about this if 16M section is not acceptable ? == NOT TESTED AT ALL, EVEN NOT COMPILED == register address of mem_section to memmap itself's page struct's pg->private field. This means the page is used for memmap of the section. Otherwise, the page is used for other purpose and memmap has a hole. --- arch/arm/mm/init.c | 11 ++++++++++- include/linux/mmzone.h | 19 ++++++++++++++++++- mm/sparse.c | 37 +++++++++++++++++++++++++++++++++++++ 3 files changed, 65 insertions(+), 2 deletions(-) Index: mmotm-2.6.35-0701/include/linux/mmzone.h =================================================================== --- mmotm-2.6.35-0701.orig/include/linux/mmzone.h +++ mmotm-2.6.35-0701/include/linux/mmzone.h @@ -1047,11 +1047,28 @@ static inline struct mem_section *__pfn_ return __nr_to_section(pfn_to_section_nr(pfn)); } +#ifdef CONFIG_SPARSEMEM_HAS_PIT +void mark_memmap_pit(unsigned long start, unsigned long end, bool valid); +static inline int page_valid(struct mem_section *ms, unsigned long pfn) +{ + struct page *page = pfn_to_page(pfn); + struct page *__pg = virt_to_page(page); + return __pg->private == ms; +} +#else +static inline int page_valid(struct mem_section *ms, unsigned long pfn) +{ + return 1; +} +#endif + static inline int pfn_valid(unsigned long pfn) { + struct mem_section *ms; if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) return 0; - return valid_section(__nr_to_section(pfn_to_section_nr(pfn))); + ms = __nr_to_section(pfn_to_section_nr(pfn)); + return valid_section(ms) && page_valid(ms, pfn); } static inline int pfn_present(unsigned long pfn) Index: mmotm-2.6.35-0701/mm/sparse.c =================================================================== --- mmotm-2.6.35-0701.orig/mm/sparse.c +++ mmotm-2.6.35-0701/mm/sparse.c @@ -615,6 +615,43 @@ void __init sparse_init(void) free_bootmem(__pa(usemap_map), size); } +#ifdef CONFIT_SPARSEMEM_HAS_PIT +/* + * Fill memmap's pg->private with a pointer to mem_section. + * pfn_valid() will check this later. (see include/linux/mmzone.h) + * The caller should call + * mark_memmap_pit(start, end, true) # for all allocated mem_map + * and, after that, + * mark_memmap_pit(start, end, false) # for all pits in mem_map. + * please see usage in ARM. + */ +void mark_memmap_pit(unsigned long start, unsigned long end, bool valid) +{ + struct mem_section *ms; + unsigned long pos, next; + struct page *pg; + void *memmap, *end; + unsigned long mapsize = sizeof(struct page) * PAGES_PER_SECTION; + + for (pos = start; + pos < end; pos = next) { + next = (pos + PAGES_PER_SECTION) & PAGE_SECTION_MASK; + ms = __pfn_to_section(pos); + if (!valid_section(ms)) + continue; + for (memmap = pfn_to_page(pfn), end = pfn_to_page(next-1); + memmap != end + 1; + memmap += PAGE_SIZE) { + pg = virt_to_page(memmap); + if (valid) + pg->private = ms; + else + pg->private = NULL; + } + } +} +#endif + #ifdef CONFIG_MEMORY_HOTPLUG #ifdef CONFIG_SPARSEMEM_VMEMMAP static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid, Index: mmotm-2.6.35-0701/arch/arm/mm/init.c =================================================================== --- mmotm-2.6.35-0701.orig/arch/arm/mm/init.c +++ mmotm-2.6.35-0701/arch/arm/mm/init.c @@ -234,6 +234,13 @@ static void __init arm_bootmem_free(stru arch_adjust_zones(zone_size, zhole_size); free_area_init_node(0, zone_size, min, zhole_size); + +#ifdef CONFIG_SPARSEMEM + for_each_bank(i, mi) { + mark_memmap_pit(bank_start_pfn(mi->bank[i]), + bank_end_pfn(mi->bank[i]), true); + } +#endif } #ifndef CONFIG_SPARSEMEM @@ -386,8 +393,10 @@ free_memmap(unsigned long start_pfn, uns * If there are free pages between these, * free the section of the memmap array. */ - if (pg < pgend) + if (pg < pgend) { + mark_memap_pit(pg >> PAGE_SHIFT, pgend >> PAGE_SHIFT, false); free_bootmem(pg, pgend - pg); + } } /* -- 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/