Messages in this thread | | | Subject | Re: [PATCH] mm/hotplug, x86: Disable ARCH_MEMORY_PROBE by default | From | Toshi Kani <> | Date | Wed, 17 Jul 2013 18:30:37 -0600 |
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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@hp.com> 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@hp.com> 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@hp.com> 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.
Great! I will submit an updated patch tomorrow.
> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Thanks! -Toshi
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