mm/hotplug, x86: Disable ARCH_MEMORY_PROBE by default
CONFIG_ARCH_MEMORY_PROBE enables the
/sys/devices/system/memory/probe interface, which allows a given
memory address to be hot-added as follows:
# echo start_address_of_new_memory > /sys/devices/system/memory/probe
(See Documentation/memory-hotplug.txt for more details.)
This probe interface is required on powerpc. On x86, however,
ACPI notifies a memory hotplug event to the kernel, which
performs its hotplug operation as the result.
Therefore, regular users do not need this interface on x86. This probe
interface is also error-prone and misleading that the kernel blindly
adds a given memory address without checking if the memory is present
on the system; no probing is done despite of its name.
The kernel crashes when a user requests to online a memory block
that is not present on the system. This interface is currently
used for testing as it can fake a hotplug event.
This patch disables CONFIG_ARCH_MEMORY_PROBE by default on x86,
adds its Kconfig menu entry on x86, and clarifies its use in
Documentation/ memory-hotplug.txt.
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: linux-mm@kvack.org
Cc: dave@sr71.net
Cc: isimatu.yasuaki@jp.fujitsu.com
Cc: tangchen@cn.fujitsu.com
Cc: vasilis.liaskovitis@profitbricks.com
Link: http://lkml.kernel.org/r/1374256068-26016-1-git-send-email-toshi.kani@hp.com
[ Edited it slightly. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b32ebf9..2f9d957 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1344,8 +1344,12 @@
depends on ARCH_SPARSEMEM_ENABLE
config ARCH_MEMORY_PROBE
- def_bool y
+ bool "Enable sysfs memory/probe interface"
depends on X86_64 && MEMORY_HOTPLUG
+ help
+ This option enables a sysfs memory/probe interface for testing.
+ See Documentation/memory-hotplug.txt for more information.
+ If you are unsure how to answer this question, answer N.
config ARCH_PROC_KCORE_TEXT
def_bool y