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

Michael S. Tsirkin
2020-05-07T11:34:02Z

On Thu, May 07, 2020 at 01:24:38PM +0200, David Hildenbrand wrote:
> 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
>

Don't base on linux-next please. Generally base on the tree you are
targeting, or Linus' tree.

> --
> Thanks,
>
> David / dhildenb