diff --git a/arch/x86/mm/numa_64.c b/arch/x86/mm/numa_64.c
index 45a361b16a59a3fd19427aec281f08f32f227294..848381bdd358cc1462fc9ab5503e32647f5a8d7a 100644
--- a/arch/x86/mm/numa_64.c
+++ b/arch/x86/mm/numa_64.c
@@ -205,6 +205,14 @@ static int __init numa_add_memblk_to(int nid, u64 start, u64 end,
 	return 0;
 }
 
+/**
+ * numa_remove_memblk_from - Remove one numa_memblk from a numa_meminfo
+ * @idx: Index of memblk to remove
+ * @mi: numa_meminfo to remove memblk from
+ *
+ * Remove @idx'th numa_memblk from @mi by shifting @mi->blk[] and
+ * decrementing @mi->nr_blks.
+ */
 void __init numa_remove_memblk_from(int idx, struct numa_meminfo *mi)
 {
 	mi->nr_blks--;
@@ -212,6 +220,17 @@ void __init numa_remove_memblk_from(int idx, struct numa_meminfo *mi)
 		(mi->nr_blks - idx) * sizeof(mi->blk[0]));
 }
 
+/**
+ * numa_add_memblk - Add one numa_memblk to numa_meminfo
+ * @nid: NUMA node ID of the new memblk
+ * @start: Start address of the new memblk
+ * @end: End address of the new memblk
+ *
+ * Add a new memblk to the default numa_meminfo.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
 int __init numa_add_memblk(int nid, u64 start, u64 end)
 {
 	return numa_add_memblk_to(nid, start, end, &numa_meminfo);
@@ -263,6 +282,16 @@ setup_node_bootmem(int nodeid, unsigned long start, unsigned long end)
 	node_set_online(nodeid);
 }
 
+/**
+ * numa_cleanup_meminfo - Cleanup a numa_meminfo
+ * @mi: numa_meminfo to clean up
+ *
+ * Sanitize @mi by merging and removing unncessary memblks.  Also check for
+ * conflicts and clear unused memblks.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
 int __init numa_cleanup_meminfo(struct numa_meminfo *mi)
 {
 	const u64 low = 0;
@@ -353,9 +382,11 @@ static void __init numa_nodemask_from_meminfo(nodemask_t *nodemask,
 			node_set(mi->blk[i].nid, *nodemask);
 }
 
-/*
- * Reset distance table.  The current table is freed.  The next
- * numa_set_distance() call will create a new one.
+/**
+ * numa_reset_distance - Reset NUMA distance table
+ *
+ * The current table is freed.  The next numa_set_distance() call will
+ * create a new one.
  */
 void __init numa_reset_distance(void)
 {
@@ -370,10 +401,15 @@ void __init numa_reset_distance(void)
 	numa_distance = NULL;
 }
 
-/*
- * Set the distance between node @from to @to to @distance.  If distance
- * table doesn't exist, one which is large enough to accomodate all the
- * currently known nodes will be created.
+/**
+ * numa_set_distance - Set NUMA distance from one NUMA to another
+ * @from: the 'from' node to set distance
+ * @to: the 'to'  node to set distance
+ * @distance: NUMA distance
+ *
+ * Set the distance from node @from to @to to @distance.  If distance table
+ * doesn't exist, one which is large enough to accomodate all the currently
+ * known nodes will be created.
  */
 void __init numa_set_distance(int from, int to, int distance)
 {
diff --git a/arch/x86/mm/numa_emulation.c b/arch/x86/mm/numa_emulation.c
index 23fa2d00253ae7ca5ae5f3682f22b6da71a9b3f9..607a2e8bc87a239223d80bc0a04a262e0ab78952 100644
--- a/arch/x86/mm/numa_emulation.c
+++ b/arch/x86/mm/numa_emulation.c
@@ -267,9 +267,32 @@ static int __init split_nodes_size_interleave(struct numa_meminfo *ei,
 	return 0;
 }
 
-/*
- * Sets up the system RAM area from start_pfn to last_pfn according to the
- * numa=fake command-line option.
+/**
+ * numa_emulation - Emulate NUMA nodes
+ * @numa_meminfo: NUMA configuration to massage
+ * @numa_dist_cnt: The size of the physical NUMA distance table
+ *
+ * Emulate NUMA nodes according to the numa=fake kernel parameter.
+ * @numa_meminfo contains the physical memory configuration and is modified
+ * to reflect the emulated configuration on success.  @numa_dist_cnt is
+ * used to determine the size of the physical distance table.
+ *
+ * On success, the following modifications are made.
+ *
+ * - @numa_meminfo is updated to reflect the emulated nodes.
+ *
+ * - __apicid_to_node[] is updated such that APIC IDs are mapped to the
+ *   emulated nodes.
+ *
+ * - NUMA distance table is rebuilt to represent distances between emulated
+ *   nodes.  The distances are determined considering how emulated nodes
+ *   are mapped to physical nodes and match the actual distances.
+ *
+ * - emu_nid_to_phys[] reflects how emulated nodes are mapped to physical
+ *   nodes.  This is used by numa_add_cpu() and numa_remove_cpu().
+ *
+ * If emulation is not enabled or fails, emu_nid_to_phys[] is filled with
+ * identity mapping and no other modification is made.
  */
 void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt)
 {