Messages in this thread | | | Date | Wed, 24 May 2017 09:36:46 -0500 | From | Reza Arbab <> | Subject | Re: [Patch 2/2]: powerpc/hotplug/mm: Fix hot-add memory node assoc |
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On Tue, May 23, 2017 at 05:44:23PM -0500, Michael Bringmann wrote: >On 05/23/2017 04:49 PM, Reza Arbab wrote: >> On Tue, May 23, 2017 at 03:05:08PM -0500, Michael Bringmann wrote: >>> On 05/23/2017 10:52 AM, Reza Arbab wrote: >>>> On Tue, May 23, 2017 at 10:15:44AM -0500, Michael Bringmann wrote: >>>>> +static void setup_nodes(void) >>>>> +{ >>>>> + int i, l = 32 /* MAX_NUMNODES */; >>>>> + >>>>> + for (i = 0; i < l; i++) { >>>>> + if (!node_possible(i)) { >>>>> + setup_node_data(i, 0, 0); >>>>> + node_set(i, node_possible_map); >>>>> + } >>>>> + } >>>>> +} >>>> >>>> This seems to be a workaround for 3af229f2071f ("powerpc/numa: Reset node_possible_map to only node_online_map"). >>> >>> They may be related, but that commit is not a replacement. The above patch ensures that >>> there are enough of the nodes initialized at startup to allow for memory hot-add into a >>> node that was not used at boot. (See 'setup_node_data' function in 'numa.c'.) That and >>> recording that the node was initialized. >> >> Is it really necessary to preinitialize these empty nodes using setup_node_data()? When you do memory hotadd into a node that was not used at boot, the node data already gets set up by >> >> add_memory >> add_memory_resource >> hotadd_new_pgdat >> arch_alloc_nodedata <-- allocs the pg_data_t >> ... >> free_area_init_node <-- sets NODE_DATA(nid)->node_id, etc. >> >> Removing setup_node_data() from that loop leaves only the call to node_set(). If 3af229f2071f (which reduces node_possible_map) was reverted, you wouldn't need to do that either. > >With or without 3af229f2071f, we would still need to add something, somewhere to add new >bits to the 'node_possible_map'. That is not being done.
Without 3af229f2071f, those bits would already BE set in node_possible_map. You wouldn't have to do anything.
-- Reza Arbab
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