Apply memory policies to top two highest zones when highest zone is ZONE_MOVABLE

The NUMA layer only supports NUMA policies for the highest zone.  When
ZONE_MOVABLE is configured with kernelcore=, the the highest zone becomes
ZONE_MOVABLE.  The result is that policies are only applied to allocations
like anonymous pages and page cache allocated from ZONE_MOVABLE when the
zone is used.

This patch applies policies to the two highest zones when the highest zone
is ZONE_MOVABLE.  As ZONE_MOVABLE consists of pages from the highest "real"
zone, it's always functionally equivalent.

The patch has been tested on a variety of machines both NUMA and non-NUMA
covering x86, x86_64 and ppc64.  No abnormal results were seen in
kernbench, tbench, dbench or hackbench.  It passes regression tests from
the numactl package with and without kernelcore= once numactl tests are
patched to wait for vmstat counters to update.

akpm: this is the nasty hack to fix NUMA mempolicies in the presence of
ZONE_MOVABLE and kernelcore= in 2.6.23.  Christoph says "For .24 either merge
the mobility or get the other solution that Mel is working on.  That solution
would only use a single zonelist per node and filter on the fly.  That may
help performance and also help to make memory policies work better."

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by:  Lee Schermerhorn <lee.schermerhorn@hp.com>
Tested-by:  Lee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: Christoph Lameter <clameter@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3da85b81dab..6427653023a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1157,6 +1157,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order,
 	nodemask_t *allowednodes = NULL;/* zonelist_cache approximation */
 	int zlc_active = 0;		/* set if using zonelist_cache */
 	int did_zlc_setup = 0;		/* just call zlc_setup() one time */
+	enum zone_type highest_zoneidx = -1; /* Gets set for policy zonelists */
 
 zonelist_scan:
 	/*
@@ -1166,6 +1167,18 @@ zonelist_scan:
 	z = zonelist->zones;
 
 	do {
+		/*
+		 * In NUMA, this could be a policy zonelist which contains
+		 * zones that may not be allowed by the current gfp_mask.
+		 * Check the zone is allowed by the current flags
+		 */
+		if (unlikely(alloc_should_filter_zonelist(zonelist))) {
+			if (highest_zoneidx == -1)
+				highest_zoneidx = gfp_zone(gfp_mask);
+			if (zone_idx(*z) > highest_zoneidx)
+				continue;
+		}
+
 		if (NUMA_BUILD && zlc_active &&
 			!zlc_zone_worth_trying(zonelist, z, allowednodes))
 				continue;