Change ALLOC_NO_WATERMARK page allocation such that dipping into the reserves
becomes a system wide event.

This has the advantage that logic dealing with reserve pages need not be node
aware (when we're this low on memory speed is usually not an issue).

Signed-off-by: Peter Zijlstra <redacted>
Cc: Lee Schermerhorn <redacted>
Cc: Christoph Lameter <redacted>
---
 mm/page_alloc.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

Index: linux-2.6-2/mm/page_alloc.c
===================================================================

--- linux-2.6-2.orig/mm/page_alloc.c
+++ linux-2.6-2/mm/page_alloc.c

@@ -1311,6 +1311,21 @@ restart:
 rebalance:
 	if (alloc_flags & ALLOC_NO_WATERMARKS) {
 nofail_alloc:
+		/*
+		 * break out of mempolicy boundaries
+		 */
+		zonelist = NODE_DATA(numa_node_id())->node_zonelists +
+			gfp_zone(gfp_mask);
+
+		/*
+		 * Before going bare metal, try to get a page above the
+		 * critical threshold - ignoring CPU sets.
+		 */
+		page = get_page_from_freelist(gfp_mask, order, zonelist,
+				ALLOC_WMARK_MIN|ALLOC_HIGH|ALLOC_HARDER);
+		if (page)
+			goto got_pg;
+
 		/* go through the zonelist yet again, ignoring mins */
 		page = get_page_from_freelist(gfp_mask, order, zonelist,
 				ALLOC_NO_WATERMARKS);

--

--

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