2 files changed, 58 insertions, 3 deletions

diff --git a/lib/Kconfig b/lib/Kconfig
index fd4118e097f0..2ba43c4a5b07 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -159,4 +159,11 @@ config CHECK_SIGNATURE
 config HAVE_LMB
         boolean
 
+config CPUMASK_OFFSTACK
+        bool "Force CPU masks off stack" if DEBUG_PER_CPU_MAPS
+        help
+          Use dynamic allocation for cpumask_var_t, instead of putting
+          them on the stack.  This is a bit more expensive, but avoids
+          stack overflow.
+
 endmenu
diff --git a/lib/cpumask.c b/lib/cpumask.c
index 8d03f22c6ced..a24edf137f41 100644
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -76,15 +76,28 @@ int cpumask_any_but(const struct cpumask *mask, unsigned int cpu)
 
 /* These are not inline because of header tangles. */
 #ifdef CONFIG_CPUMASK_OFFSTACK
-bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
+/**
+ * alloc_cpumask_var_node - allocate a struct cpumask on a given node
+ * @mask: pointer to cpumask_var_t where the cpumask is returned
+ * @flags: GFP_ flags
+ *
+ * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
+ * a nop returning a constant 1 (in <linux/cpumask.h>)
+ * Returns TRUE if memory allocation succeeded, FALSE otherwise.
+ *
+ * In addition, mask will be NULL if this fails.  Note that gcc is
+ * usually smart enough to know that mask can never be NULL if
+ * CONFIG_CPUMASK_OFFSTACK=n, so does code elimination in that case
+ * too.
+ */
+bool alloc_cpumask_var_node(cpumask_var_t *mask, gfp_t flags, int node)
 {
         if (likely(slab_is_available()))
-                *mask = kmalloc(cpumask_size(), flags);
+                *mask = kmalloc_node(cpumask_size(), flags, node);
         else {
 #ifdef CONFIG_DEBUG_PER_CPU_MAPS
                 printk(KERN_ERR
                         "=> alloc_cpumask_var: kmalloc not available!\n");
-                dump_stack();
 #endif
                 *mask = NULL;
         }
@@ -96,19 +109,54 @@ bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
 #endif
         return *mask != NULL;
 }
+EXPORT_SYMBOL(alloc_cpumask_var_node);
+
+/**
+ * alloc_cpumask_var - allocate a struct cpumask
+ * @mask: pointer to cpumask_var_t where the cpumask is returned
+ * @flags: GFP_ flags
+ *
+ * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
+ * a nop returning a constant 1 (in <linux/cpumask.h>).
+ *
+ * See alloc_cpumask_var_node.
+ */
+bool alloc_cpumask_var(cpumask_var_t *mask, gfp_t flags)
+{
+        return alloc_cpumask_var_node(mask, flags, numa_node_id());
+}
 EXPORT_SYMBOL(alloc_cpumask_var);
 
+/**
+ * alloc_bootmem_cpumask_var - allocate a struct cpumask from the bootmem arena.
+ * @mask: pointer to cpumask_var_t where the cpumask is returned
+ *
+ * Only defined when CONFIG_CPUMASK_OFFSTACK=y, otherwise is
+ * a nop returning a constant 1 (in <linux/cpumask.h>)
+ * Either returns an allocated (zero-filled) cpumask, or causes the
+ * system to panic.
+ */
 void __init alloc_bootmem_cpumask_var(cpumask_var_t *mask)
 {
         *mask = alloc_bootmem(cpumask_size());
 }
 
+/**
+ * free_cpumask_var - frees memory allocated for a struct cpumask.
+ * @mask: cpumask to free
+ *
+ * This is safe on a NULL mask.
+ */
 void free_cpumask_var(cpumask_var_t mask)
 {
         kfree(mask);
 }
 EXPORT_SYMBOL(free_cpumask_var);
 
+/**
+ * free_bootmem_cpumask_var - frees result of alloc_bootmem_cpumask_var
+ * @mask: cpumask to free
+ */
 void __init free_bootmem_cpumask_var(cpumask_var_t mask)
 {
         free_bootmem((unsigned long)mask, cpumask_size());