CONFIG_ARCH_MEMORY_PROBE enables /sys/devices/system/memory/probe interface, which allows a given memory address to be hot-added as follows. (See Documentation/memory-hotplug.txt for more detail.) # echo start_address_of_new_memory > /sys/devices/system/memory/probe 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, users should not be required to use this interface on x86. This probe interface is also error-prone 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 patch disables CONFIG_ARCH_MEMORY_PROBE by default on x86, and clarifies it in Documentation/memory-hotplug.txt. Signed-off-by: Toshi Kani <toshi.kani@xxxxxx> --- Documentation/memory-hotplug.txt | 7 ++++--- arch/x86/Kconfig | 2 +- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/Documentation/memory-hotplug.txt b/Documentation/memory-hotplug.txt index 8e5eacb..396d871 100644 --- a/Documentation/memory-hotplug.txt +++ b/Documentation/memory-hotplug.txt @@ -214,9 +214,10 @@ In some environments, especially virtualized environment, firmware will not notify memory hotplug event to the kernel. For such environment, "probe" interface is supported. This interface depends on CONFIG_ARCH_MEMORY_PROBE. -Now, CONFIG_ARCH_MEMORY_PROBE is supported only by powerpc but it does not -contain highly architecture codes. Please add config if you need "probe" -interface. +CONFIG_ARCH_MEMORY_PROBE is supported on powerpc only. On x86, this config +option is disabled by default since ACPI notifies a memory hotplug event to +the kernel, which performs its hotplug operation as the result. Please +enable this option if you need the "probe" interface on x86. Probe interface is located at /sys/devices/system/memory/probe diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index b32ebf9..0729682 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1344,7 +1344,7 @@ config ARCH_SELECT_MEMORY_MODEL depends on ARCH_SPARSEMEM_ENABLE config ARCH_MEMORY_PROBE - def_bool y + def_bool n depends on X86_64 && MEMORY_HOTPLUG config ARCH_PROC_KCORE_TEXT -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>