mm/memory_hotplug: remove HIGHMEM leftovers

We don't support CONFIG_MEMORY_HOTPLUG on 32 bit and consequently not
HIGHMEM.  Let's remove any leftover code -- including the unused
"status_change_nid_high" field part of the memory notifier.

Link: https://lkml.kernel.org/r/20210929143600.49379-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Alex Shi <alexs@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/core-api/memory-hotplug.rst

@@ -57,16 +57,13 @@ The third argument (arg) passes a pointer of struct memory_notify::
 		unsigned long start_pfn;
 		unsigned long nr_pages;
 		int status_change_nid_normal;
-		int status_change_nid_high;
 		int status_change_nid;
 	}
 
 - start_pfn is start_pfn of online/offline memory.
 - nr_pages is # of pages of online/offline memory.
 - status_change_nid_normal is set node id when N_NORMAL_MEMORY of nodemask
   is (will be) set/clear, if this is -1, then nodemask status is not changed.
-- status_change_nid_high is set node id when N_HIGH_MEMORY of nodemask
-  is (will be) set/clear, if this is -1, then nodemask status is not changed.
 - status_change_nid is set node id when N_MEMORY of nodemask is (will be)
   set/clear. It means a new(memoryless) node gets new memory by online and a
   node loses all memory. If this is -1, then nodemask status is not changed.

Documentation/translations/zh_CN/core-api/memory-hotplug.rst

@@ -63,7 +63,6 @@ memory_notify结构体的指针::
 		unsigned long start_pfn;
 		unsigned long nr_pages;
 		int status_change_nid_normal;
-		int status_change_nid_high;
 		int status_change_nid;
 	}
 
@@ -74,9 +73,6 @@ memory_notify结构体的指针::
 - status_change_nid_normal是当nodemask的N_NORMAL_MEMORY被设置/清除时设置节
   点id，如果是-1，则nodemask状态不改变。
 
-- status_change_nid_high是当nodemask的N_HIGH_MEMORY被设置/清除时设置的节点
-  id，如果这个值为-1，那么nodemask状态不会改变。
-
 - status_change_nid是当nodemask的N_MEMORY被（将）设置/清除时设置的节点id。这
   意味着一个新的（没上线的）节点通过联机获得新的内存，而一个节点失去了所有的内
   存。如果这个值为-1，那么nodemask的状态就不会改变。

include/linux/memory.h

@@ -96,7 +96,6 @@ struct memory_notify {
 	unsigned long start_pfn;
 	unsigned long nr_pages;
 	int status_change_nid_normal;
-	int status_change_nid_high;
 	int status_change_nid;
 };
 

mm/memory_hotplug.c

@@ -21,7 +21,6 @@
 #include <linux/memory.h>
 #include <linux/memremap.h>
 #include <linux/memory_hotplug.h>
-#include <linux/highmem.h>
 #include <linux/vmalloc.h>
 #include <linux/ioport.h>
 #include <linux/delay.h>
@@ -585,10 +584,6 @@ void generic_online_page(struct page *page, unsigned int order)
 	debug_pagealloc_map_pages(page, 1 << order);
 	__free_pages_core(page, order);
 	totalram_pages_add(1UL << order);
-#ifdef CONFIG_HIGHMEM
-	if (PageHighMem(page))
-		totalhigh_pages_add(1UL << order);
-#endif
 }
 EXPORT_SYMBOL_GPL(generic_online_page);
 
@@ -625,26 +620,18 @@ static void node_states_check_changes_online(unsigned long nr_pages,
 
 	arg->status_change_nid = NUMA_NO_NODE;
 	arg->status_change_nid_normal = NUMA_NO_NODE;
-	arg->status_change_nid_high = NUMA_NO_NODE;
 
 	if (!node_state(nid, N_MEMORY))
 		arg->status_change_nid = nid;
 	if (zone_idx(zone) <= ZONE_NORMAL && !node_state(nid, N_NORMAL_MEMORY))
 		arg->status_change_nid_normal = nid;
-#ifdef CONFIG_HIGHMEM
-	if (zone_idx(zone) <= ZONE_HIGHMEM && !node_state(nid, N_HIGH_MEMORY))
-		arg->status_change_nid_high = nid;
-#endif
 }
 
 static void node_states_set_node(int node, struct memory_notify *arg)
 {
 	if (arg->status_change_nid_normal >= 0)
 		node_set_state(node, N_NORMAL_MEMORY);
 
-	if (arg->status_change_nid_high >= 0)
-		node_set_state(node, N_HIGH_MEMORY);
-
 	if (arg->status_change_nid >= 0)
 		node_set_state(node, N_MEMORY);
 }
@@ -1801,7 +1788,6 @@ static void node_states_check_changes_offline(unsigned long nr_pages,
 
 	arg->status_change_nid = NUMA_NO_NODE;
 	arg->status_change_nid_normal = NUMA_NO_NODE;
-	arg->status_change_nid_high = NUMA_NO_NODE;
 
 	/*
 	 * Check whether node_states[N_NORMAL_MEMORY] will be changed.
@@ -1816,24 +1802,9 @@ static void node_states_check_changes_offline(unsigned long nr_pages,
 	if (zone_idx(zone) <= ZONE_NORMAL && nr_pages >= present_pages)
 		arg->status_change_nid_normal = zone_to_nid(zone);
 
-#ifdef CONFIG_HIGHMEM
-	/*
-	 * node_states[N_HIGH_MEMORY] contains nodes which
-	 * have normal memory or high memory.
-	 * Here we add the present_pages belonging to ZONE_HIGHMEM.
-	 * If the zone is within the range of [0..ZONE_HIGHMEM), and
-	 * we determine that the zones in that range become empty,
-	 * we need to clear the node for N_HIGH_MEMORY.
-	 */
-	present_pages += pgdat->node_zones[ZONE_HIGHMEM].present_pages;
-	if (zone_idx(zone) <= ZONE_HIGHMEM && nr_pages >= present_pages)
-		arg->status_change_nid_high = zone_to_nid(zone);
-#endif
-
 	/*
-	 * We have accounted the pages from [0..ZONE_NORMAL), and
-	 * in case of CONFIG_HIGHMEM the pages from ZONE_HIGHMEM
-	 * as well.
+	 * We have accounted the pages from [0..ZONE_NORMAL); ZONE_HIGHMEM
+	 * does not apply as we don't support 32bit.
 	 * Here we count the possible pages from ZONE_MOVABLE.
 	 * If after having accounted all the pages, we see that the nr_pages
 	 * to be offlined is over or equal to the accounted pages,
@@ -1851,9 +1822,6 @@ static void node_states_clear_node(int node, struct memory_notify *arg)
 	if (arg->status_change_nid_normal >= 0)
 		node_clear_state(node, N_NORMAL_MEMORY);
 
-	if (arg->status_change_nid_high >= 0)
-		node_clear_state(node, N_HIGH_MEMORY);
-
 	if (arg->status_change_nid >= 0)
 		node_clear_state(node, N_MEMORY);
 }