From: Michael Bringmann <mwb@linux.vnet.ibm.com>
Date: Fri, 8 Sep 2017 20:47:56 +0000 (-0500)
Subject: powerpc/vphn: Fix numa update end-loop bug
X-Git-Tag: v4.15-rc1~81^2~106
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=8bc931495d4bfcde6bb242a478ddd1186ae29301;p=users%2Fjedix%2Flinux-maple.git

powerpc/vphn: Fix numa update end-loop bug

powerpc/vphn: On Power systems with shared configurations of CPUs
and memory, there are some issues with the association of additional
CPUs and memory to nodes when hot-adding resources.  This patch
fixes an end-of-updates processing problem observed occasionally
in numa_update_cpu_topology().

Signed-off-by: Michael Bringmann <mwb@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 32f5f8db46ec..ec098b3f7332 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1401,16 +1401,22 @@ int numa_update_cpu_topology(bool cpus_locked)
 
 		for_each_cpu(sibling, cpu_sibling_mask(cpu)) {
 			ud = &updates[i++];
+			ud->next = &updates[i];
 			ud->cpu = sibling;
 			ud->new_nid = new_nid;
 			ud->old_nid = numa_cpu_lookup_table[sibling];
 			cpumask_set_cpu(sibling, &updated_cpus);
-			if (i < weight)
-				ud->next = &updates[i];
 		}
 		cpu = cpu_last_thread_sibling(cpu);
 	}
 
+	/*
+	 * Prevent processing of 'updates' from overflowing array
+	 * where last entry filled in a 'next' pointer.
+	 */
+	if (i)
+		updates[i-1].next = NULL;
+
 	pr_debug("Topology update for the following CPUs:\n");
 	if (cpumask_weight(&updated_cpus)) {
 		for (ud = &updates[0]; ud; ud = ud->next) {