Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753134AbaBRBbN (ORCPT ); Mon, 17 Feb 2014 20:31:13 -0500 Received: from e7.ny.us.ibm.com ([32.97.182.137]:41803 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751097AbaBRBbL (ORCPT ); Mon, 17 Feb 2014 20:31:11 -0500 Date: Mon, 17 Feb 2014 17:31:00 -0800 From: Nishanth Aravamudan To: David Rientjes Cc: Linus Torvalds , Raghavendra K T , Andrew Morton , Fengguang Wu , David Cohen , Al Viro , Damien Ramonda , Jan Kara , linux-mm , Linux Kernel Mailing List Subject: Re: [RFC PATCH V5] mm readahead: Fix readahead fail for no local memory and limit readahead pages Message-ID: <20140218013100.GA31998@linux.vnet.ibm.com> References: <52FC6F2A.30905@linux.vnet.ibm.com> <52FC98A6.1000701@linux.vnet.ibm.com> <20140214001438.GB1651@linux.vnet.ibm.com> <20140214043235.GA21999@linux.vnet.ibm.com> <20140217192803.GA14586@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Operating-System: Linux 3.11.0-15-generic (x86_64) User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14021801-5806-0000-0000-000024277510 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17.02.2014 [15:14:06 -0800], David Rientjes wrote: > On Mon, 17 Feb 2014, Nishanth Aravamudan wrote: > > > Here is what I'm running into now: > > > > setup_arch -> > > do_init_bootmem -> > > cpu_numa_callback -> > > numa_setup_cpu -> > > map_cpu_to_node -> > > update_numa_cpu_lookup_table > > > > Which current updates the powerpc specific numa_cpu_lookup_table. I > > would like to update that function to use set_cpu_numa_node() and > > set_cpu_numa_mem(), but local_memory_node() is not yet functional > > because build_all_zonelists is called later in start_kernel. Would it > > make sense for first_zones_zonelist() to return NUMA_NO_NODE if we > > don't have a zone? > > > > Hmm, I don't think we'll want to modify the generic first_zones_zonelist() > for a special case that is only true during boot. Instead, would it make > sense to modify numa_setup_cpu() to use the generic cpu_to_node() instead > of using a powerpc mapping and then do the set_cpu_numa_mem() after > paging_init() when the zonelists will have been built and zones without > present pages are properly excluded? Sorry, I was unclear in my e-mail. I meant to modify local_memory_node(), not first_zones_zonelist(). Well, it only needs the following, I think? diff --git a/mm/page_alloc.c b/mm/page_alloc.c index e3758a0..5de4337 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3650,6 +3650,8 @@ int local_memory_node(int node) gfp_zone(GFP_KERNEL), NULL, &zone); + if (!zone) + return NUMA_NO_NODE; return zone->node; } #endif I think that condition should only happen during boot -- maybe even deserving of an unlikely, but I don't think the above is considered a hot-path. If the above isn't palatable, I can look into your suggestion instead. Thanks, Nish -- 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/