From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yasunori Goto Date: Tue, 04 Jul 2006 05:51:04 +0000 Subject: [Patch:BUG] oversight of copy pgdat array on each node for ia64's memory hotplug. Message-Id: <20060704143906.8350.Y-GOTO@jp.fujitsu.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Andrew Morton Cc: "Luck, Tony" , Linux Kernel ML , linux-ia64@vger.kernel.org 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. Please apply. Signed-off-by: Yasunori Goto --- arch/ia64/mm/discontig.c | 17 +++++++++++++---- 1 files changed, 13 insertions(+), 4 deletions(-) Index: pgdattest1/arch/ia64/mm/discontig.c =================================--- pgdattest1.orig/arch/ia64/mm/discontig.c 2006-07-03 15:41:30.000000000 +0900 +++ pgdattest1/arch/ia64/mm/discontig.c 2006-07-03 15:44:48.000000000 +0900 @@ -313,10 +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_map() can't be used at here. + * node_online_map is not set for hot-added node at this time, + * because here is halfway of initilization of new node's structure. + * If for_each_online_node() is used, 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)); + } + } /** -- Yasunori Goto