[Devel] [PATCH RHEL7 COMMIT] ms/kasan: disable memory hotplug

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-229.7.2-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-229.7.2.vz7.6.6
------>
commit 2aab6eabec66429c34f23086f82dd793d660b283
Author: Andrey Ryabinin <aryabinin at odin.com>
Date:   Thu Sep 3 19:27:36 2015 +0400

    ms/kasan: disable memory hotplug
    
    https://jira.sw.ru/browse/PSBM-26429
    
    From: Andrey Ryabinin <a.ryabinin at samsung.com>
    
    commit 786a8959912eb94fc2381c2ae487a96ce55dabca upstream.
    
    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 at samsung.com>
    Cc: Dmitry Vyukov <dvyukov at google.com>
    Cc: Konstantin Serebryany <kcc at google.com>
    Cc: Dmitry Chernenkov <dmitryc at google.com>
    Signed-off-by: Andrey Konovalov <adech.fo at gmail.com>
    Cc: Yuri Gribov <tetra2005 at gmail.com>
    Cc: Konstantin Khlebnikov <koct9i at gmail.com>
    Cc: Sasha Levin <sasha.levin at oracle.com>
    Cc: Christoph Lameter <cl at linux.com>
    Cc: Joonsoo Kim <iamjoonsoo.kim at lge.com>
    Cc: Dave Hansen <dave.hansen at intel.com>
    Cc: Andi Kleen <andi at firstfloor.org>
    Cc: Ingo Molnar <mingo at elte.hu>
    Cc: Thomas Gleixner <tglx at linutronix.de>
    Cc: "H. Peter Anvin" <hpa at zytor.com>
    Cc: Christoph Lameter <cl at linux.com>
    Cc: Pekka Enberg <penberg at kernel.org>
    Cc: David Rientjes <rientjes at google.com>
    Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
    Signed-off-by: Andrey Ryabinin <aryabinin at odin.com>
    
    Signed-off-by: Andrey Ryabinin <aryabinin at odin.com>
---
 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