Re: [PATCH 0/2] memory-hotplug : notification of memoty block's state

Ni zhan Chen
2012-10-02T09:42:49Z

On 10/02/2012 04:25 PM, Yasuaki Ishimatsu wrote:
> We are trying to implement a physical memory hot removing function as
> following thread.
>
> https://lkml.org/lkml/2012/9/5/201
>
> But there is not enough review to merge into linux kernel.
>
> I think there are following blockades.
> 1. no physical memory hot removable system
> 2. huge patch-set
>
> If you have a KVM system, we can get rid of 1st blockade. Because
> applying following patch, we can create memory hot removable system
> on KVM guest.
>
> http://lists.gnu.org/archive/html/qemu-devel/2012-07/msg01389.html
>
> 2nd blockade is own problem. So we try to divide huge patch into
> a small patch in each function as follows:
>
> - bug fix
> - acpi framework
> - kernel core
>
> We had already sent bug fix patches.
>
> https://lkml.org/lkml/2012/9/27/39
>
> And the patch fixes following bug.
>
> remove_memory() offlines memory. And it is called by following two cases:
>
> 1. echo offline >/sys/devices/system/memory/memoryXX/state
> 2. hot remove a memory device
>
> In the 1st case, the memory block's state is changed and the notification
> that memory block's state changed is sent to userland after calling
> offline_memory(). So user can notice memory block is changed.,

Hi Yasuaki,

Thanks for splitting the patchset, it's more easier to review this time.
One question:

How can notify userspace? you mean function node_memory_callback or
...., but
this function basically do nothing.

>
> But in the 2nd case, the memory block's state is not changed and the
> notification is not also sent to userspcae even if calling offline_memory().
> So user cannot notice memory block is changed.
>
> We should also notify to userspace at 2nd case.
>
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