mm/page_alloc: print node fallback order

Patch series "Fix NUMA nodes fallback list ordering".

For a NUMA system that has multiple nodes at same distance from other
nodes, the fallback list generation prefers same node order for them
instead of round-robin thereby penalizing one node over others.  This
series fixes it.

More description of the problem and the fix is present in the patch
description.

This patch (of 2):

Print information message about the allocation fallback order for each
NUMA node during boot.

No functional changes here.  This makes it easier to illustrate the
problem in the node fallback list generation, which the next patch
fixes.

Link: https://lkml.kernel.org/r/20210830121603.1081-1-bharata@amd.com
Link: https://lkml.kernel.org/r/20210830121603.1081-2-bharata@amd.com
Signed-off-by: Bharata B Rao <bharata@amd.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Krupa Ramakrishnan <krupa.ramakrishnan@amd.com>
Cc: Sadagopan Srinivasan <Sadagopan.Srinivasan@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 307ad23cb9e9b3df32bf4000b9c468c8fbc8d805..163f60dcac47f2f5336f51cffbeb46ebaa138e39 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6262,6 +6262,10 @@ static void build_zonelists(pg_data_t *pgdat)
 
        build_zonelists_in_node_order(pgdat, node_order, nr_nodes);
        build_thisnode_zonelists(pgdat);
+       pr_info("Fallback order for Node %d: ", local_node);
+       for (node = 0; node < nr_nodes; node++)
+               pr_cont("%d ", node_order[node]);
+       pr_cont("\n");
 }
 
 #ifdef CONFIG_HAVE_MEMORYLESS_NODES