[PATCH 3/4] lumpy ensure we respect zone boundaries

Andy Whitcroft
2006-12-06T17:01:18Z

lumpy: ensure we respect zone boundaries

When scanning an aligned order N area ensure we only pull out pages
in the same zone as our tag page, else we will manipulate those
pages' LRU under the wrong zone lru_lock. Bad.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 0effa3e..85f626b 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -660,6 +660,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
struct page *page, *tmp;
unsigned long scan, pfn, end_pfn, page_pfn;
int active;
+ int zone_id;

for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
page = lru_to_page(src);
@@ -691,6 +692,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
* surrounding the tag page. Only take those pages of
* the same active state as that tag page.
*/
+ zone_id = page_zone_id(page);
page_pfn = __page_to_pfn(page);
pfn = page_pfn & ~((1 << order) - 1);
end_pfn = pfn + (1 << order);
@@ -700,8 +702,10 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
if (unlikely(!pfn_valid(pfn)))
break;

- scan++;
tmp = __pfn_to_page(pfn);
+ if (unlikely(page_zone_id(tmp) != zone_id))
+ continue;
+ scan++;
switch (__isolate_lru_page(tmp, active)) {
case 0:
list_move(&tmp->lru, dst);