mm: Add notifier framework for showing memory
There are many drivers in the kernel which can hold on
to lots of memory. It can be useful to dump out all those
drivers at key points in the kernel. Introduct a notifier
framework for dumping this information. When the notifiers
are called, drivers can dump out the state of any memory
they may be using.
Change-Id: Ifb2946964bf5d072552dd56d8d6dfdd794af6d84
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>
[swatsrid@codeaurora.org: Fix merge conflicts and errors]
Signed-off-by: Swathi Sridhar <swatsrid@codeaurora.org>
diff --git a/mm/showmem.c b/mm/showmem.c
new file mode 100644
index 0000000..a7e3caf
--- /dev/null
+++ b/mm/showmem.c
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018, 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>
+
+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_SIMPLE_ATTRIBUTE(show_mem_notifier_debug_ops, show_mem_notifier_get,
+ NULL, "%llu\n");
+
+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);