Merge "mm: Add notifier framework for showing memory"

include/linux/show_mem_notifier.h

@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/notifier.h>
+
+int show_mem_notifier_register(struct notifier_block *nb);
+
+int show_mem_notifier_unregister(struct notifier_block *nb);
+
+void show_mem_call_notifiers(void);

mm/Makefile

@@ -42,7 +42,7 @@ obj-y			:= filemap.o mempool.o oom_kill.o fadvise.o \
 			   mm_init.o mmu_context.o percpu.o slab_common.o \
 			   compaction.o vmacache.o \
 			   interval_tree.o list_lru.o workingset.o \
-			   debug.o gup.o $(mmu-y)
+			   debug.o gup.o $(mmu-y) showmem.o
 
 # Give 'page_alloc' its own module-parameter namespace
 page-alloc-y := page_alloc.o

mm/showmem.c

@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/notifier.h>
+#include <linux/debugfs.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/show_mem_notifier.h>
+
+static BLOCKING_NOTIFIER_HEAD(show_mem_notifier);
+
+int show_mem_notifier_register(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&show_mem_notifier, nb);
+}
+
+int show_mem_notifier_unregister(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&show_mem_notifier, nb);
+}
+
+void show_mem_call_notifiers(void)
+{
+	blocking_notifier_call_chain(&show_mem_notifier, 0, NULL);
+}
+
+static int show_mem_notifier_get(void *dat, u64 *val)
+{
+	show_mem_call_notifiers();
+	*val = 0;
+	return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(show_mem_notifier_debug_ops, show_mem_notifier_get,
+				NULL, "%llu\n");
+
+static int show_mem_notifier_debugfs_register(void)
+{
+	debugfs_create_file("show_mem_notifier", 0664, NULL, NULL,
+				&show_mem_notifier_debug_ops);
+
+	return 0;
+}
+late_initcall(show_mem_notifier_debugfs_register);