Messages in this thread | | | Date | Fri, 18 Jan 2008 21:30:11 +0000 | From | Mel Gorman <> | Subject | Re: crash in kmem_cache_init |
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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
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