linux-kernel - [RFC v9 PATCH 19/21] memory-hotplug: remove sysfs file of node

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Message-Id: <1346837155-534-20-git-send-email-wency@cn.fujitsu.com>
Date:	Wed, 5 Sep 2012 17:25:53 +0800
From:	wency@...fujitsu.com
To:	x86@...nel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, linux-acpi@...r.kernel.org,
	linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
	linux-ia64@...r.kernel.org, cmetcalf@...era.com,
	sparclinux@...r.kernel.org
Cc:	rientjes@...gle.com, liuj97@...il.com, len.brown@...el.com,
	benh@...nel.crashing.org, paulus@...ba.org, cl@...ux.com,
	minchan.kim@...il.com, akpm@...ux-foundation.org,
	kosaki.motohiro@...fujitsu.com, isimatu.yasuaki@...fujitsu.com,
	Wen Congyang <wency@...fujitsu.com>
Subject: [RFC v9 PATCH 19/21] memory-hotplug: remove sysfs file of node

From: Wen Congyang <wency@...fujitsu.com>

This patch introduces a new function try_offline_node() to
remove sysfs file of node when all memory sections of this
node are removed. If some memory sections of this node are
not removed, this function does nothing.

CC: David Rientjes <rientjes@...gle.com>
CC: Jiang Liu <liuj97@...il.com>
CC: Len Brown <len.brown@...el.com>
CC: Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC: Paul Mackerras <paulus@...ba.org>
CC: Christoph Lameter <cl@...ux.com>
Cc: Minchan Kim <minchan.kim@...il.com>
CC: Andrew Morton <akpm@...ux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
CC: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Signed-off-by: Wen Congyang <wency@...fujitsu.com>
---
 mm/memory_hotplug.c |   54 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 54 insertions(+), 0 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index afda7e9..270c249 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -29,6 +29,7 @@
 #include <linux/suspend.h>
 #include <linux/mm_inline.h>
 #include <linux/firmware-map.h>
+#include <linux/stop_machine.h>
 
 #include <asm/tlbflush.h>
 
@@ -1285,6 +1286,57 @@ int offline_memory(u64 start, u64 size)
 	return 0;
 }
 
+static int check_cpu_on_node(void *data)
+{
+	struct pglist_data *pgdat = data;
+	int cpu;
+
+	for_each_online_cpu(cpu) {
+		if (cpu_to_node(cpu) == pgdat->node_id)
+			/*
+			 * the cpu on this node is onlined, and we can't
+			 * offline this node.
+			 */
+			return -EBUSY;
+	}
+
+	return 0;
+}
+
+/* offline the node if all memory sections of this node are removed */
+static void try_offline_node(int nid)
+{
+	unsigned long start_pfn = NODE_DATA(nid)->node_start_pfn;
+	unsigned long end_pfn = start_pfn + NODE_DATA(nid)->node_spanned_pages;
+	unsigned long pfn;
+
+	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+		unsigned long section_nr = pfn_to_section_nr(pfn);
+
+		if (!present_section_nr(section_nr))
+			continue;
+
+		if (pfn_to_nid(pfn) != nid)
+			continue;
+
+		/*
+		 * some memory sections of this node are not removed, and we
+		 * can't offline node now.
+		 */
+		return;
+	}
+
+	if (stop_machine(check_cpu_on_node, NODE_DATA(nid), NULL))
+		return;
+
+	/*
+	 * all memory sections of this node are removed, we can offline this
+	 * node now.
+	 */
+	node_set_offline(nid);
+	unregister_one_node(nid);
+}
+
 int __ref remove_memory(int nid, u64 start, u64 size)
 {
 	int ret = 0;
@@ -1305,6 +1357,8 @@ int __ref remove_memory(int nid, u64 start, u64 size)
 	firmware_map_remove(start, start + size, "System RAM");
 
 	arch_remove_memory(start, size);
+
+	try_offline_node(nid);
 out:
 	unlock_memory_hotplug();
 	return ret;
-- 
1.7.1

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