false NUMA OOM

From: William Lee Irwin III (wli@holomorphy.com)
Date: Mon Sep 16 2002 - 21:50:35 EST


Well, there's an obvious problem. shrink_caches() hammers out_of_memory()
when it has only looked at a single node. Something like this might help.

Totally untested. Problem discovered during 2 simultaneous dbench 512's
on separate 12GB tmpfs fs's on a 32x NUMA-Q with 32GB of RAM.

Against 2.5.35.

Bill

--- mm/vmscan.c.orig 2002-09-16 19:02:11.000000000 -0700
+++ mm/vmscan.c 2002-09-16 19:07:50.000000000 -0700
@@ -519,18 +519,24 @@
 shrink_caches(struct zone *classzone, int priority,
                 int gfp_mask, int nr_pages)
 {
+ pg_data_t *pgdat;
         struct zone *first_classzone;
         struct zone *zone;
+ int type;
 
         first_classzone = classzone->zone_pgdat->node_zones;
- zone = classzone;
- while (zone >= first_classzone && nr_pages > 0) {
- if (zone->free_pages <= zone->pages_high) {
- nr_pages = shrink_zone(zone, priority,
- gfp_mask, nr_pages);
+ for (type = classzone - first_classzone; type >= 0; --type)
+ for_each_pgdat(pgdat) {
+ zone = pgdat->node_zones + type;
+ if (!zone->size)
+ continue;
+ if (zone->free_pages <= zone->pages_high)
+ nr_pages = shrink_zone(zone, priority,
+ gfp_mask, nr_pages);
+ if (nr_pages <= 0)
+ return nr_pages;
                 }
- zone--;
- }
+
         return nr_pages;
 }
 
-
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