[patch 026/155] revert "topology: add support for node_to_mem_node() to determine the fallback node"

[Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>]

From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: revert "topology: add support for node_to_mem_node() to determine the fallback node"

This reverts commit ad2c8144418c6a81cefe65379fd47bbe8344cef2.

The function node_to_mem_node() was introduced by that commit for use in SLUB
on systems with memoryless nodes, but it turned out to be unreliable on some
architectures/configurations and a simpler solution exists than fixing it up.

Thus commit 0715e6c516f1 ("mm, slub: prevent kmalloc_node crashes and
memory leaks") removed the only user of node_to_mem_node() and we can
revert the commit that introduced the function.

Link: http://lkml.kernel.org/r/20200320115533.9604-2-vbabka@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Bharata B Rao <bharata@xxxxxxxxxxxxx>
Cc: Christopher Lameter <cl@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Nathan Lynch <nathanl@xxxxxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: PUVICHAKRAVARTHY RAMACHANDRAN <puvichakravarthy@xxxxxxxxxx>
Cc: Sachin Sant <sachinp@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 include/linux/topology.h |   17 -----------------
 mm/page_alloc.c          |    1 -
 2 files changed, 18 deletions(-)

--- a/include/linux/topology.h~revert-topology-add-support-for-node_to_mem_node-to-determine-the-fallback-node
+++ a/include/linux/topology.h
@@ -130,20 +130,11 @@ static inline int numa_node_id(void)
  * Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem().
  */
 DECLARE_PER_CPU(int, _numa_mem_);
-extern int _node_numa_mem_[MAX_NUMNODES];
 
 #ifndef set_numa_mem
 static inline void set_numa_mem(int node)
 {
 	this_cpu_write(_numa_mem_, node);
-	_node_numa_mem_[numa_node_id()] = node;
-}
-#endif
-
-#ifndef node_to_mem_node
-static inline int node_to_mem_node(int node)
-{
-	return _node_numa_mem_[node];
 }
 #endif
 
@@ -166,7 +157,6 @@ static inline int cpu_to_mem(int cpu)
 static inline void set_cpu_numa_mem(int cpu, int node)
 {
 	per_cpu(_numa_mem_, cpu) = node;
-	_node_numa_mem_[cpu_to_node(cpu)] = node;
 }
 #endif
 
@@ -180,13 +170,6 @@ static inline int numa_mem_id(void)
 }
 #endif
 
-#ifndef node_to_mem_node
-static inline int node_to_mem_node(int node)
-{
-	return node;
-}
-#endif
-
 #ifndef cpu_to_mem
 static inline int cpu_to_mem(int cpu)
 {
--- a/mm/page_alloc.c~revert-topology-add-support-for-node_to_mem_node-to-determine-the-fallback-node
+++ a/mm/page_alloc.c
@@ -95,7 +95,6 @@ DEFINE_STATIC_KEY_TRUE(vm_numa_stat_key)
  */
 DEFINE_PER_CPU(int, _numa_mem_);		/* Kernel "local memory" node */
 EXPORT_PER_CPU_SYMBOL(_numa_mem_);
-int _node_numa_mem_[MAX_NUMNODES];
 #endif
 
 /* work_structs for global per-cpu drains */
_