linux-kernel - [Patch 2/2]: powerpc/hotplug/mm: Fix hot-add memory node assoc

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Message-Id: <3bb44d92-b2ff-e197-4bdf-ec6d588d6dab@linux.vnet.ibm.com>
Date:   Tue, 23 May 2017 10:15:44 -0500
From:   Michael Bringmann <mwb@...ux.vnet.ibm.com>
To:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Reza Arbab <arbab@...ux.vnet.ibm.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Bharata B Rao <bharata@...ux.vnet.ib>,
        Balbir Singh <bsingharora@...il.com>,
        Michael Bringmann <mwb@...ux.vnet.ibm.com>,
        Shailendra Singh <shailendras@...dia.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [Patch 2/2]: powerpc/hotplug/mm: Fix hot-add memory node assoc


Removing or adding memory via the PowerPC hotplug interface shows
anomalies in the association between memory and nodes.  The code
was updated to initialize more possible nodes to make them available
to subsequent DLPAR hotplug-memory operations, even if they are not
needed at boot time.

Signed-off-by: Michael Bringmann <mwb@...ux.vnet.ibm.com>
---
 arch/powerpc/mm/numa.c |   44 ++++++++++++++++++++++++++++++++------------
 1 file changed, 32 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 15c2dd5..3d58c1f 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -870,7 +870,7 @@ void __init dump_numa_cpu_topology(void)
 }
 
 /* Initialize NODE_DATA for a node on the local memory */
-static void __init setup_node_data(int nid, u64 start_pfn, u64 end_pfn)
+static void setup_node_data(int nid, u64 start_pfn, u64 end_pfn)
 {
 	u64 spanned_pages = end_pfn - start_pfn;
 	const size_t nd_size = roundup(sizeof(pg_data_t), SMP_CACHE_BYTES);
@@ -878,23 +878,41 @@ static void __init setup_node_data(int nid, u64 start_pfn, u64 end_pfn)
 	void *nd;
 	int tnid;
 
-	nd_pa = memblock_alloc_try_nid(nd_size, SMP_CACHE_BYTES, nid);
-	nd = __va(nd_pa);
+	if (!node_data[nid]) {
+		nd_pa = memblock_alloc_try_nid(nd_size, SMP_CACHE_BYTES, nid);
+		nd = __va(nd_pa);
 
-	/* report and initialize */
-	pr_info("  NODE_DATA [mem %#010Lx-%#010Lx]\n",
-		nd_pa, nd_pa + nd_size - 1);
-	tnid = early_pfn_to_nid(nd_pa >> PAGE_SHIFT);
-	if (tnid != nid)
-		pr_info("    NODE_DATA(%d) on node %d\n", nid, tnid);
+		node_data[nid] = nd;
+		memset(NODE_DATA(nid), 0, sizeof(pg_data_t));
+		NODE_DATA(nid)->node_id = nid;
+
+		/* report and initialize */
+		pr_info("  NODE_DATA [mem %#010Lx-%#010Lx]\n",
+			nd_pa, nd_pa + nd_size - 1);
+		tnid = early_pfn_to_nid(nd_pa >> PAGE_SHIFT);
+		if (tnid != nid)
+			pr_info("    NODE_DATA(%d) on node %d\n", nid, tnid);
+	} else {
+		nd_pa = (u64) node_data[nid];
+		nd = __va(nd_pa);
+	}
 
-	node_data[nid] = nd;
-	memset(NODE_DATA(nid), 0, sizeof(pg_data_t));
-	NODE_DATA(nid)->node_id = nid;
 	NODE_DATA(nid)->node_start_pfn = start_pfn;
 	NODE_DATA(nid)->node_spanned_pages = spanned_pages;
 }
 
+static void setup_nodes(void)
+{
+	int i, l = 32 /* MAX_NUMNODES */;
+
+	for (i = 0; i < l; i++) {
+		if (!node_possible(i)) {
+			setup_node_data(i, 0, 0);
+			node_set(i, node_possible_map);
+		}
+	}
+}
+
 void __init initmem_init(void)
 {
 	int nid, cpu;
@@ -914,6 +932,8 @@ void __init initmem_init(void)
 	 */
 	nodes_and(node_possible_map, node_possible_map, node_online_map);
 
+	setup_nodes();
+
 	for_each_online_node(nid) {
 		unsigned long start_pfn, end_pfn;