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authorDavid S. Miller <davem@davemloft.net>2010-10-06 19:39:31 -0700
committerDavid S. Miller <davem@davemloft.net>2010-10-06 19:39:31 -0700
commit69259abb64d4da77273bf59accfc9fa79e7165f4 (patch)
treebd043ab03a788b749c8d5ae4049d8defae9abf34 /mm/mmzone.c
parentdd53df265b1ee7a1fbbc76bb62c3bec2383bbd44 (diff)
parent12e94471b2be5ef9b55b10004a3a2cd819490036 (diff)
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Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
Conflicts: drivers/net/pcmcia/pcnet_cs.c net/caif/caif_socket.c
Diffstat (limited to 'mm/mmzone.c')
-rw-r--r--mm/mmzone.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/mm/mmzone.c b/mm/mmzone.c
index f5b7d17..e35bfb8 100644
--- a/mm/mmzone.c
+++ b/mm/mmzone.c
@@ -87,3 +87,24 @@ int memmap_valid_within(unsigned long pfn,
return 1;
}
#endif /* CONFIG_ARCH_HAS_HOLES_MEMORYMODEL */
+
+#ifdef CONFIG_SMP
+/* Called when a more accurate view of NR_FREE_PAGES is needed */
+unsigned long zone_nr_free_pages(struct zone *zone)
+{
+ unsigned long nr_free_pages = zone_page_state(zone, NR_FREE_PAGES);
+
+ /*
+ * While kswapd is awake, it is considered the zone is under some
+ * memory pressure. Under pressure, there is a risk that
+ * per-cpu-counter-drift will allow the min watermark to be breached
+ * potentially causing a live-lock. While kswapd is awake and
+ * free pages are low, get a better estimate for free pages
+ */
+ if (nr_free_pages < zone->percpu_drift_mark &&
+ !waitqueue_active(&zone->zone_pgdat->kswapd_wait))
+ return zone_page_state_snapshot(zone, NR_FREE_PAGES);
+
+ return nr_free_pages;
+}
+#endif /* CONFIG_SMP */