linux-kernel - [PATCH V13 4/4] powerpc/vphn: Fix numa update end-loop bug

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Message-Id: <b967cb9b-efc4-3ff3-27c8-876a81250133@linux.vnet.ibm.com>
Date:   Fri, 1 Sep 2017 10:48:15 -0500
From:   Michael Bringmann <mwb@...ux.vnet.ibm.com>
To:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Cc:     Michael Bringmann <mwb@...ux.vnet.ibm.com>,
        Nathan Fontenot <nfont@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        John Allen <jallen@...ux.vnet.ibm.com>
Subject: [PATCH V13 4/4] 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@...ux.vnet.ibm.com>
---
 arch/powerpc/mm/numa.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 3a5b334..fccf23f 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1410,6 +1410,13 @@ int numa_update_cpu_topology(bool cpus_locked)
 		cpu = cpu_last_thread_sibling(cpu);
 	}
 
+	/*
+	 * Prevent processing of 'updates' from overflowing array
+	 * in cases 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) {