The patch titled
Fix copying of pgdat array on each node for ia64 memory hotplug
has been added to the -mm tree. Its filename is
fix-copying-of-pgdat-array-on-each-node-for-ia64-memory-hotplug.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: Fix copying of pgdat array on each node for ia64 memory hotplug
From: Yasunori Goto <y-goto@xxxxxxxxxxxxxx>
Hello.
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@xxxxxxxxxxxxxx>
Cc: "Luck, Tony" <tony.luck@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
arch/ia64/mm/discontig.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff -puN arch/ia64/mm/discontig.c~fix-copying-of-pgdat-array-on-each-node-for-ia64-memory-hotplug arch/ia64/mm/discontig.c
--- a/arch/ia64/mm/discontig.c~fix-copying-of-pgdat-array-on-each-node-for-ia64-memory-hotplug
+++ a/arch/ia64/mm/discontig.c
@@ -313,9 +313,19 @@ static void __meminit scatter_node_data(
pg_data_t **dst;
int node;
- for_each_online_node(node) {
- dst = LOCAL_DATA_ADDR(pgdat_list[node])->pg_data_ptrs;
- memcpy(dst, pgdat_list, sizeof(pgdat_list));
+ /*
+ * 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));
+ }
}
}
_
Patches currently in -mm which might be from y-goto@xxxxxxxxxxxxxx are
origin.patch
fix-copying-of-pgdat-array-on-each-node-for-ia64-memory-hotplug.patch
-
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