From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <436BC20B.9070704@shadowen.org> Date: Fri, 04 Nov 2005 20:18:19 +0000 From: Andy Whitcroft MIME-Version: 1.0 Subject: Re: [PATCH] powerpc: mem_init crash for sparsemem References: <200511041631.17237.arnd@arndb.de> In-Reply-To: <200511041631.17237.arnd@arndb.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Arnd Bergmann Cc: linuxppc64-dev@ozlabs.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Arnd Bergmann wrote: > I have a Cell blade with some broken memory in the middle of the > physical address space and this is correctly detected by the > firmware, but not relocated. When I enable CONFIG_SPARSEMEM, > the memsections for the nonexistant address space do not > get struct page entries allocated, as expected. > > However, mem_init for the non-NUMA configuration tries to > access these pages without first looking if they are there. > I'm currently using the hack below to work around that, but > I have the feeling that there should be a cleaner solution > for this. > > Please comment. > > Signed-off-by: Arnd Bergmann > > --- linux-2.6.15-rc.orig/arch/powerpc/mm/mem.c > +++ linux-2.6.15-rc/arch/powerpc/mm/mem.c > @@ -348,6 +348,9 @@ void __init mem_init(void) > #endif > for_each_pgdat(pgdat) { > for (i = 0; i < pgdat->node_spanned_pages; i++) { > + if (!section_has_mem_map(__pfn_to_section > + (pgdat->node_start_pfn + i))) > + continue; > page = pgdat_page_nr(pgdat, i); > if (PageReserved(page)) > reservedpages++; Would it not make sense to use pfn_valid(), as that is not sparsemem specific? Not looked at the code in question specifically, but if you can use section_has_mem_map() it should be equivalent: if (!pfn_valid(pgdat->node_start_pfn + i)) continue; Want to spin us a patch and I'll give it some general testing. -apw -- 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