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.
I didn't see where any part of commit 3af229f2071f would touch the
'node_possible_map'
which is needed by 'numa.c' and 'workqueue.c'. The nodemask created and
updated by
'mem_cgroup_may_update_nodemask()' does not appear to be the same mask.
Are you sure you're looking at 3af229f2071f? It only adds one line of
code; the reduction of node_possible_map.
--
Reza Arbab
