Commit dd8041f1 authored Jul 04, 2006 by Yasunori Goto Committed by Linus Torvalds Jul 04, 2006

[PATCH] Fix copying of pgdat array on each node for ia64 memory hotplug



I found a bug in memory hot-add code for ia64.

IA64's code has copies of pgdat's array on each node to reduce memory
access over crossing node.  This array is used by NODE_DATA() macro.  When
new node is hot-added, this pgdat's array should be updated and copied on
new node too.

However, I used for_each_online_node() in scatter_node_data() to copy
it. This meant its array is not copied on new node.
Because initialization of structures for new node was halfway,
so online_node_map couldn't be set at this time.

To copy arrays on new node, I changed it to check value of pgdat_list[]
which is source array of copies.  I tested this patch with my Memory Hotadd
emulation on Tiger4.  This patch is for 2.6.17-git20.

Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent 31304c90

arch/ia64/mm/discontig.c

+13 −3

Original line number	Diff line number	Diff line
		@@ -313,11 +313,21 @@ static void __meminit scatter_node_data(void)
		pg_data_t **dst;
		int node;

		for_each_online_node(node) {
		/*
		* for_each_online_node() can't be used at here.
		* node_online_map is not set for hot-added nodes at this time,
		* because we are halfway through initialization of the new node's
		* structures. If for_each_online_node() is used, a new node's
		* pg_data_ptrs will be not initialized. Insted of using it,
		* pgdat_list[] is checked.
		*/
		for_each_node(node) {
		if (pgdat_list[node]) {
		dst = LOCAL_DATA_ADDR(pgdat_list[node])->pg_data_ptrs;
		memcpy(dst, pgdat_list, sizeof(pgdat_list));
		}
		}
		}

		/**
		* initialize_pernode_data - fixup per-cpu & per-node pointers