Re: [PATCH v3 07/15] mm/memory_hotplug: Introduce offline_and_remove_memory()

David Hildenbrand
2020-05-07T11:25:05Z

On 07.05.20 12:46, Michael S. Tsirkin wrote:
> On Thu, May 07, 2020 at 12:31:11PM +0200, David Hildenbrand wrote:
>> virtio-mem wants to offline and remove a memory block once it unplugged
>> all subblocks (e.g., using alloc_contig_range()). Let's provide
>> an interface to do that from a driver. virtio-mem already supports to
>> offline partially unplugged memory blocks. Offlining a fully unplugged
>> memory block will not require to migrate any pages. All unplugged
>> subblocks are PageOffline() and have a reference count of 0 - so
>> offlining code will simply skip them.
>>
>> All we need is an interface to offline and remove the memory from kernel
>> module context, where we don't have access to the memory block devices
>> (esp. find_memory_block() and device_offline()) and the device hotplug
>> lock.
>>
>> To keep things simple, allow to only work on a single memory block.
>>
>> Acked-by: Michal Hocko <mhocko@suse.com>
>> Tested-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: David Hildenbrand <david@redhat.com>
>> Cc: Oscar Salvador <osalvador@suse.com>
>> Cc: Michal Hocko <mhocko@suse.com>
>> Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
>> Cc: Wei Yang <richard.weiyang@gmail.com>
>> Cc: Dan Williams <dan.j.williams@intel.com>
>> Cc: Qian Cai <cai@lca.pw>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
>
>
> didn't you lose Andrew Morton's ack here?

Yeah, thanks for noticing.

>
>> ---
>> include/linux/memory_hotplug.h | 1 +
>> mm/memory_hotplug.c | 37 ++++++++++++++++++++++++++++++++++
>> 2 files changed, 38 insertions(+)
>
> I get:
>
> error: sha1 information is lacking or useless (mm/memory_hotplug.c).
> error: could not build fake ancestor
>
> which version is this against? Pls post patches on top of some tag
> in Linus' tree if possible.

As the cover states, latest linux-next. To be precise

commit 6b43f715b6379433e8eb30aa9bcc99bd6a585f77 (tag: next-20200507,
next/master)
Author: Stephen Rothwell <sfr@canb.auug.org.au>
Date: Thu May 7 18:11:31 2020 +1000

Add linux-next specific files for 20200507

--
Thanks,

David / dhildenb