From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 18 Jan 2008 21:30:11 +0000 From: Mel Gorman Subject: Re: crash in kmem_cache_init Message-ID: <20080118213011.GC10491@csn.ul.ie> References: <20080115150949.GA14089@aepfle.de> <84144f020801170414q7d408a74uf47a84b777c36a4a@mail.gmail.com> <20080117181222.GA24411@aepfle.de> <20080117211511.GA25320@aepfle.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Olaf Hering , Pekka Enberg , linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, Linux MM List-ID: On (18/01/08 10:47), Christoph Lameter didst pronounce: > On Thu, 17 Jan 2008, Olaf Hering wrote: > > > early_node_map[1] active PFN ranges > > 1: 0 -> 892928 > > Could not find start_pfn for node 0 > > Corrupted min_pfn? > Doubtful. Node 0 has no memory but it is still being initialised. Still, I looked closer at what is going on when that message gets displayed and I see this in free_area_init_nodes() for_each_online_node(nid) { pg_data_t *pgdat = NODE_DATA(nid); free_area_init_node(nid, pgdat, NULL, find_min_pfn_for_node(nid), NULL); /* Any memory on that node */ if (pgdat->node_present_pages) node_set_state(nid, N_HIGH_MEMORY); check_for_regular_memory(pgdat); } This "Any memory on that node" thing is new and it says if there is any memory on the node, set N_HIGH_MEMORY. Fine I guess, I haven't tracked these changes closely. It calls check_for_regular_memory() which looks like static void check_for_regular_memory(pg_data_t *pgdat) { #ifdef CONFIG_HIGHMEM enum zone_type zone_type; for (zone_type = 0; zone_type <= ZONE_NORMAL; zone_type++) { struct zone *zone = &pgdat->node_zones[zone_type]; if (zone->present_pages) node_set_state(zone_to_nid(zone), N_NORMAL_MEMORY); } #endif } i.e. go through the other zones and if any of them have memory, set N_NORMAL_MEMORY. But... it only does this on CONFIG_HIGHMEM which on PPC64 is not going to be set so N_NORMAL_MEMORY never gets set on POWER.... That sounds bad. mel@arnold:~/git/linux-2.6/mm$ grep -n N_NORMAL_MEMORY slab.c 1593: for_each_node_state(nid, N_NORMAL_MEMORY) { 1971: for_each_node_state(node, N_NORMAL_MEMORY) { 2102: for_each_node_state(node, N_NORMAL_MEMORY) { 3818: for_each_node_state(node, N_NORMAL_MEMORY) { and one of them is in kmem_cache_init(). That seems very significant. Christoph, can you think of possibilities of where N_NORMAL_MEMORY not being set would cause trouble for slab? -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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