[V5 PATCH 02/26] memory_hotplug: handle empty zone when online_movable/online_kernel

[Lai Jiangshan]

make online_movable/online_kernel can empty a zone
or can move memory to a empty zone.

Signed-off-by: Lai Jiangshan <la...@cn.fujitsu.com>
---
 mm/memory_hotplug.c |   51 +++++++++++++++++++++++++++++++++++++++++++++------
 1 files changed, 45 insertions(+), 6 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 6d3bec4..bdcdaf6 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -227,8 +227,17 @@ static void resize_zone(struct zone *zone, unsigned long 
start_pfn,
 
        zone_span_writelock(zone);
 
-       zone->zone_start_pfn = start_pfn;
-       zone->spanned_pages = end_pfn - start_pfn;
+       if (end_pfn - start_pfn) {
+               zone->zone_start_pfn = start_pfn;
+               zone->spanned_pages = end_pfn - start_pfn;
+       } else {
+               /*
+                * make it consist as free_area_init_core(),
+                * if spanned_pages = 0, then keep start_pfn = 0
+                */
+               zone->zone_start_pfn = 0;
+               zone->spanned_pages = 0;
+       }
 
        zone_span_writeunlock(zone);
 }
@@ -244,10 +253,19 @@ static void fix_zone_id(struct zone *zone, unsigned long 
start_pfn,
                set_page_links(pfn_to_page(pfn), zid, nid, pfn);
 }
 
-static int move_pfn_range_left(struct zone *z1, struct zone *z2,
+static int __meminit move_pfn_range_left(struct zone *z1, struct zone *z2,
                unsigned long start_pfn, unsigned long end_pfn)
 {
+       int ret;
        unsigned long flags;
+       unsigned long z1_start_pfn;
+
+       if (!z1->wait_table) {
+               ret = init_currently_empty_zone(z1, start_pfn,
+                       end_pfn - start_pfn, MEMMAP_HOTPLUG);
+               if (ret)
+                       return ret;
+       }
 
        pgdat_resize_lock(z1->zone_pgdat, &flags);
 
@@ -261,7 +279,13 @@ static int move_pfn_range_left(struct zone *z1, struct 
zone *z2,
        if (end_pfn <= z2->zone_start_pfn)
                goto out_fail;
 
-       resize_zone(z1, z1->zone_start_pfn, end_pfn);
+       /* use start_pfn for z1's start_pfn if z1 is empty */
+       if (z1->spanned_pages)
+               z1_start_pfn = z1->zone_start_pfn;
+       else
+               z1_start_pfn = start_pfn;
+
+       resize_zone(z1, z1_start_pfn, end_pfn);
        resize_zone(z2, end_pfn, z2->zone_start_pfn + z2->spanned_pages);
 
        pgdat_resize_unlock(z1->zone_pgdat, &flags);
@@ -274,10 +298,19 @@ out_fail:
        return -1;
 }
 
-static int move_pfn_range_right(struct zone *z1, struct zone *z2,
+static int __meminit move_pfn_range_right(struct zone *z1, struct zone *z2,
                unsigned long start_pfn, unsigned long end_pfn)
 {
+       int ret;
        unsigned long flags;
+       unsigned long z2_end_pfn;
+
+       if (!z2->wait_table) {
+               ret = init_currently_empty_zone(z2, start_pfn,
+                       end_pfn - start_pfn, MEMMAP_HOTPLUG);
+               if (ret)
+                       return ret;
+       }
 
        pgdat_resize_lock(z1->zone_pgdat, &flags);
 
@@ -291,8 +324,14 @@ static int move_pfn_range_right(struct zone *z1, struct 
zone *z2,
        if (start_pfn >= z1->zone_start_pfn + z1->spanned_pages)
                goto out_fail;
 
+       /* use end_pfn for z2's end_pfn if z2 is empty */
+       if (z2->spanned_pages)
+               z2_end_pfn = z2->zone_start_pfn + z2->spanned_pages;
+       else
+               z2_end_pfn = end_pfn;
+
        resize_zone(z1, z1->zone_start_pfn, start_pfn);
-       resize_zone(z2, start_pfn, z2->zone_start_pfn + z2->spanned_pages);
+       resize_zone(z2, start_pfn, z2_end_pfn);
 
        pgdat_resize_unlock(z1->zone_pgdat, &flags);
 
-- 
1.7.4.4

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