[PATCH v11 03/19] kasan: disable memory hotplug

[Andrey Ryabinin]

Currently memory hotplug won't work with KASan.
As we don't have shadow for hotplugged memory,
kernel will crash on the first access to it.
To make this work we will need to allocate shadow
for new memory.

At some future point proper memory hotplug support
will be implemented. Until then, print a warning at startup and
disable memory hot-add.

Signed-off-by: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
---
 mm/kasan/kasan.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 6dc1aa7..def8110 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -20,6 +20,7 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/memblock.h>
+#include <linux/memory.h>
 #include <linux/mm.h>
 #include <linux/printk.h>
 #include <linux/sched.h>
@@ -300,3 +301,23 @@ EXPORT_SYMBOL(__asan_storeN_noabort);
 /* to shut up compiler complaints */
 void __asan_handle_no_return(void) {}
 EXPORT_SYMBOL(__asan_handle_no_return);
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+static int kasan_mem_notifier(struct notifier_block *nb,
+			unsigned long action, void *data)
+{
+	return (action == MEM_GOING_ONLINE) ? NOTIFY_BAD : NOTIFY_OK;
+}
+
+static int __init kasan_memhotplug_init(void)
+{
+	pr_err("WARNING: KASan doesn't support memory hot-add\n");
+	pr_err("Memory hot-add will be disabled\n");
+
+	hotplug_memory_notifier(kasan_mem_notifier, 0);
+
+	return 0;
+}
+
+module_init(kasan_memhotplug_init);
+#endif
-- 
2.2.2

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