[PATCH: 010/017]Memory hotplug for new nodes v.4.(allocate wait table)

[Yasunori Goto]

Wait_table is initialized according to zone size at boot time.
But, we cannot know the maixmum zone size when memory hotplug is enabled.
It can be changed.... And resizing of wait_table is too hard.

So kernel allocate and initialzie wait_table as its maximum size.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Signed-off-by: Yasunori Goto <y-goto@xxxxxxxxxxxxxx>

 mm/page_alloc.c |   45 +++++++++++++++++++++++++++++++++++++++------
 1 files changed, 39 insertions(+), 6 deletions(-)

Index: pgdat8/mm/page_alloc.c
===================================================================
--- pgdat8.orig/mm/page_alloc.c	2006-03-17 11:13:18.466550152 +0900
+++ pgdat8/mm/page_alloc.c	2006-03-17 11:19:32.371677992 +0900
@@ -1788,6 +1788,7 @@ void __init build_all_zonelists(void)
  */
 #define PAGES_PER_WAITQUEUE	256
 
+#ifdef CONFIG_MEMORY_HOTPLUG
 static inline unsigned long wait_table_size(unsigned long pages)
 {
 	unsigned long size = 1;
@@ -1806,6 +1807,17 @@ static inline unsigned long wait_table_s
 
 	return max(size, 4UL);
 }
+#else
+/*
+ * Because zone size might be changed by hot-add,
+ * We can't determin suitable size for wait_table as traditional.
+ * So, we use maximum size.
+ */
+static inline unsigned long wait_table_size(unsigned long pages)
+{
+	return 4096UL;
+}
+#endif
 
 /*
  * This is an integer logarithm so that shifts can be used later
@@ -2074,7 +2086,7 @@ void __init setup_per_cpu_pageset(void)
 #endif
 
 static __meminit
-void zone_wait_table_init(struct zone *zone, unsigned long zone_size_pages)
+int zone_wait_table_init(struct zone *zone, unsigned long zone_size_pages)
 {
 	int i;
 	struct pglist_data *pgdat = zone->zone_pgdat;
@@ -2085,12 +2097,37 @@ void zone_wait_table_init(struct zone *z
 	 */
 	zone->wait_table_size = wait_table_size(zone_size_pages);
 	zone->wait_table_bits =	wait_table_bits(zone->wait_table_size);
-	zone->wait_table = (wait_queue_head_t *)
-		alloc_bootmem_node(pgdat, zone->wait_table_size
-					* sizeof(wait_queue_head_t));
+	if (system_state == SYSTEM_BOOTING) {
+		zone->wait_table = (wait_queue_head_t *)
+			alloc_bootmem_node(pgdat, zone->wait_table_size
+						* sizeof(wait_queue_head_t));
+	} else {
+		int table_size;
+		/*
+		 * XXX: This is the case that new node is hotadded.
+		 * 	At this time, kmalloc() will not get this new node's
+		 *	memory. Because this wait_table must be initialized,
+		 *	to use this new node itself. To use this new node's
+		 *	memory, further consideration will be necessary.
+		 */
+		do {
+			table_size = zone->wait_table_size
+					* sizeof(wait_queue_head_t);
+			zone->wait_table = kmalloc(table_size, GFP_KERNEL);
+			if (!zone->wait_table) {
+				/* try half size */
+				zone->wait_table_size >>= 1;
+				zone->wait_table_bits =
+					wait_table_bits(zone->wait_table_size);
+			}
+		} while (zone->wait_table_size && !zone->wait_table);
+	}
+	if (!zone->wait_table)
+		return -ENOMEM;
 
 	for(i = 0; i < zone->wait_table_size; ++i)
 		init_waitqueue_head(zone->wait_table + i);
+	return 0;
 }
 
 static __meminit void zone_pcp_init(struct zone *zone)
@@ -2116,8 +2153,10 @@ __meminit int init_currently_empty_zone(
 					unsigned long size)
 {
 	struct pglist_data *pgdat = zone->zone_pgdat;
-
-	zone_wait_table_init(zone, size);
+	int ret;
+	ret = zone_wait_table_init(zone, size);
+	if (ret)
+		return ret;
 	pgdat->nr_zones = zone_idx(zone) + 1;
 
 	zone->zone_start_pfn = zone_start_pfn;

-- 
Yasunori Goto 


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