[PATCH] memory hotplug locking: zone span seqlock

See the "fixup bad_range()" patch for more information, but this actually
creates a the lock to protect things making assumptions about a zone's size
staying constant at runtime.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 14 insertions, 5 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 32fad6d23200..817635f2ab62 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -33,6 +33,7 @@
 #include <linux/sysctl.h>
 #include <linux/cpu.h>
 #include <linux/cpuset.h>
+#include <linux/memory_hotplug.h>
 #include <linux/nodemask.h>
 #include <linux/vmalloc.h>
 
@@ -80,12 +81,19 @@ unsigned long __initdata nr_all_pages;
 
 static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
 {
-        if (page_to_pfn(page) >= zone->zone_start_pfn + zone->spanned_pages)
-                return 1;
-        if (page_to_pfn(page) < zone->zone_start_pfn)
-                return 1;
+        int ret = 0;
+        unsigned seq;
+        unsigned long pfn = page_to_pfn(page);
 
-        return 0;
+        do {
+                seq = zone_span_seqbegin(zone);
+                if (pfn >= zone->zone_start_pfn + zone->spanned_pages)
+                        ret = 1;
+                else if (pfn < zone->zone_start_pfn)
+                        ret = 1;
+        } while (zone_span_seqretry(zone, seq));
+
+        return ret;
 }
 
 static int page_is_consistent(struct zone *zone, struct page *page)
@@ -1980,6 +1988,7 @@ static void __init free_area_init_core(struct pglist_data *pgdat,
                 zone->name = zone_names[j];
                 spin_lock_init(&zone->lock);
                 spin_lock_init(&zone->lru_lock);
+                zone_seqlock_init(zone);
                 zone->zone_pgdat = pgdat;
                 zone->free_pages = 0;