mm: slab-allocate memory section nodemask for large systems

Nodemasks should not be allocated on the stack for large systems (when it
is larger than 256 bytes) since there is a threat of overflow.

This patch causes the unregister_mem_sect_under_nodes() nodemask to be
allocated on the stack for smaller systems and be allocated by slab for
larger systems.

GFP_KERNEL is used since remove_memory_block() can block.

Cc: Gary Hade <garyhade@us.ibm.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Alex Chiang <achiang@hp.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 4 deletions

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 41414113b9f0..70122791683d 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -363,12 +363,16 @@ int register_mem_sect_under_node(struct memory_block *mem_blk, int nid)
 /* unregister memory section under all nodes that it spans */
 int unregister_mem_sect_under_nodes(struct memory_block *mem_blk)
 {
-        nodemask_t unlinked_nodes;
+        NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
         unsigned long pfn, sect_start_pfn, sect_end_pfn;
 
-        if (!mem_blk)
+        if (!mem_blk) {
+                NODEMASK_FREE(unlinked_nodes);
                 return -EFAULT;
-        nodes_clear(unlinked_nodes);
+        }
+        if (!unlinked_nodes)
+                return -ENOMEM;
+        nodes_clear(*unlinked_nodes);
         sect_start_pfn = section_nr_to_pfn(mem_blk->phys_index);
         sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
         for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
@@ -379,13 +383,14 @@ int unregister_mem_sect_under_nodes(struct memory_block *mem_blk)
                         continue;
                 if (!node_online(nid))
                         continue;
-                if (node_test_and_set(nid, unlinked_nodes))
+                if (node_test_and_set(nid, *unlinked_nodes))
                         continue;
                 sysfs_remove_link(&node_devices[nid].sysdev.kobj,
                          kobject_name(&mem_blk->sysdev.kobj));
                 sysfs_remove_link(&mem_blk->sysdev.kobj,
                          kobject_name(&node_devices[nid].sysdev.kobj));
         }
+        NODEMASK_FREE(unlinked_nodes);
         return 0;
 }