On Wed, 2013-07-17 at 20:24 -0400, KOSAKI Motohiro wrote: > On Wed, Jul 17, 2013 at 7:51 PM, Toshi Kani <toshi.kani@xxxxxx> wrote: > > On Wed, 2013-07-17 at 19:33 -0400, KOSAKI Motohiro wrote: > >> On Wed, Jul 17, 2013 at 7:29 PM, Toshi Kani <toshi.kani@xxxxxx> wrote: > >> > On Wed, 2013-07-17 at 19:22 -0400, KOSAKI Motohiro wrote: > >> >> On Wed, Jul 17, 2013 at 5:45 PM, Toshi Kani <toshi.kani@xxxxxx> wrote: > >> >> > 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. > >> >> > >> >> Why don't you completely remove it? Who should use this strange interface? > >> > > >> > According to the comment below, this probe interface is used on powerpc. > >> > So, we cannot remove it, but to disable it on x86. > >> > >> I meant x86. Why can't we completely remove ARCH_MEMORY_PROBE section > >> from x86 Kconfig? > > > > Oh, I see what you meant. I do not expect any need for end-users, but I > > was not sure if someone working on the memory hotplug development might > > use it for fake hot-add testing. Yes, if you folks do not see any need, > > I will remove it from x86 Kconfig. > > Then it's ok to submit your patch now. > > Acked-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> I just sent v2 patch, but did not put your Ack since I did not remove the option from x86 Kconfig per discussions with Dave. I'd really appreciate if you can take a look at the v2 and re-ack it if it still makes sense to you. Thanks, -Toshi -- 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>