[PATCH] mm/memory_hotplug: Fix leftover use of struct page during hotplug

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

The case of a new numa node got missed in avoiding using
the node info from page_struct during hotplug.  In this
path we have a call to register_mem_sect_under_node (which allows
us to specify it is hotplug so don't change the node),
via link_mem_sections which unfortunately does not.

Fix is to pass check_nid through link_mem_sections as well and
disable it in the new numa node path.

Note the bug only 'sometimes' manifests depending on what happens to
be in the struct page structures - there are lots of them and it only
needs to match one of them.

Fixes: fc44f7f9231a ("mm/memory_hotplug: don't read nid from struct page during hotplug")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 drivers/base/node.c  | 5 +++--
 include/linux/node.h | 8 +++++---
 mm/memory_hotplug.c  | 2 +-
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 7a3a580821e0..a5e821d09656 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -490,7 +490,8 @@ int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
 	return 0;
 }
 
-int link_mem_sections(int nid, unsigned long start_pfn, unsigned long nr_pages)
+int link_mem_sections(int nid, unsigned long start_pfn, unsigned long nr_pages,
+		      bool check_nid)
 {
 	unsigned long end_pfn = start_pfn + nr_pages;
 	unsigned long pfn;
@@ -514,7 +515,7 @@ int link_mem_sections(int nid, unsigned long start_pfn, unsigned long nr_pages)
 
 		mem_blk = find_memory_block_hinted(mem_sect, mem_blk);
 
-		ret = register_mem_sect_under_node(mem_blk, nid, true);
+		ret = register_mem_sect_under_node(mem_blk, nid, check_nid);
 		if (!err)
 			err = ret;
 
diff --git a/include/linux/node.h b/include/linux/node.h
index 41f171861dcc..6d336e38d155 100644
--- a/include/linux/node.h
+++ b/include/linux/node.h
@@ -32,9 +32,11 @@ extern struct node *node_devices[];
 typedef  void (*node_registration_func_t)(struct node *);
 
 #if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) && defined(CONFIG_NUMA)
-extern int link_mem_sections(int nid, unsigned long start_pfn, unsigned long nr_pages);
+extern int link_mem_sections(int nid, unsigned long start_pfn,
+			     unsigned long nr_pages, bool check_nid);
 #else
-static inline int link_mem_sections(int nid, unsigned long start_pfn, unsigned long nr_pages)
+static inline int link_mem_sections(int nid, unsigned long start_pfn,
+				    unsigned long nr_pages, bool check_nid)
 {
 	return 0;
 }
@@ -57,7 +59,7 @@ static inline int register_one_node(int nid)
 		if (error)
 			return error;
 		/* link memory sections under this node */
-		error = link_mem_sections(nid, pgdat->node_start_pfn, pgdat->node_spanned_pages);
+		error = link_mem_sections(nid, pgdat->node_start_pfn, pgdat->node_spanned_pages, true);
 	}
 
 	return error;
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index f74826cdceea..25982467800b 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1158,7 +1158,7 @@ int __ref add_memory_resource(int nid, struct resource *res, bool online)
 		 * nodes have to go through register_node.
 		 * TODO clean up this mess.
 		 */
-		ret = link_mem_sections(nid, start_pfn, nr_pages);
+		ret = link_mem_sections(nid, start_pfn, nr_pages, false);
 register_fail:
 		/*
 		 * If sysfs file of new node can't create, cpu on the node
-- 
2.16.2