[PATCH 3/3] reset wmark_min and inactive ratio of zone when hotplughappens V2

[Minchan Kim]

Changelog since V1 
 o Add Ack-by of Yasunori Goto
 o Modify setup_per_zone_wmarks's comment

This patch solve two problems.

Whenever memory hotplug sucessfully happens, zone->present_pages
have to be changed.

1) Now memory hotplug calls setup_per_zone_wmark_min only when
online_pages called, not offline_pages.

It breaks balance.

2) If zone->present_pages is changed, we also have to change
zone->inactive_ratio. That's because inactive_ratio depends
on zone->present_pages.

Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>
Acked-by: Yasunori Goto <y-goto@xxxxxxxxxxxxxx>
CC: Rik van Riel <riel@xxxxxxxxxx>
CC: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
CC: Johannes Weiner <hannes@xxxxxxxxxxx>
---
 mm/memory_hotplug.c |    4 ++++
 mm/page_alloc.c     |    2 +-
 2 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 037291e..e4412a6 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -423,6 +423,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
 	zone->zone_pgdat->node_present_pages += onlined_pages;
 
 	setup_per_zone_wmarks();
+	calculate_zone_inactive_ratio(zone);
 	if (onlined_pages) {
 		kswapd_run(zone_to_nid(zone));
 		node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
@@ -832,6 +833,9 @@ repeat:
 	totalram_pages -= offlined_pages;
 	num_physpages -= offlined_pages;
 
+	setup_per_zone_wmarks();
+	calculate_zone_inactive_ratio(zone);
+
 	vm_total_pages = nr_free_pagecache_pages();
 	writeback_set_ratelimit();
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f11cfbf..d13f9b5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4472,7 +4472,7 @@ static void setup_per_zone_lowmem_reserve(void)
 
 /**
  * setup_per_zone_wmarks - called when min_free_kbytes changes 
- * or when memory is hot-added
+ * or when memory is hot-{added|removed}
  *
  * Ensures that the watermark[min,low,high] values for each zone are set correctly
  * with respect to min_free_kbytes.
-- 
1.5.4.3

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