Messages in this thread | | | Subject | Re: [PATCH] mm/hotplug, x86: Disable ARCH_MEMORY_PROBE by default | From | Toshi Kani <> | Date | Thu, 18 Jul 2013 10:02:19 -0600 |
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On Thu, 2013-07-18 at 10:48 +0900, Yasuaki Ishimatsu wrote: > (2013/07/18 8:51), Toshi Kani 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. > > I do not think the interface is necessary. So I vote to Kosaki's opinion.
Thanks for the confirmation! -Toshi
> > Thanks, > Yasuaki Ishimatsu > > > > > Thanks, > > -Toshi > > > >
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