Re: [PATCH v1 2/5] mm/memory_hotplug: enforce section alignment when onlining/offlining

[Oscar Salvador <osalvador@techadventures.net>]

On Thu, Aug 16, 2018 at 12:06:25PM +0200, David Hildenbrand wrote:
> onlining/offlining code works on whole sections, so let's enforce that.
> Existing code only allows to add memory in memory block size. And only
> whole memory blocks can be onlined/offlined. Memory blocks are always
> aligned to sections, so this should not break anything.
> 
> online_pages/offline_pages will implicitly mark whole sections
> online/offline, so the code really can only handle such granularities.
> 
> (especially offlining code cannot deal with pageblock_nr_pages but
>  theoretically only MAX_ORDER-1)
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>

Hi David,

If you are really willing to move the checks from this patch[1] to
online/offline_pages, you might consider to put that in as well.
So we have a function that checks for everything, and not multiple checks.

Another thing is that I would have prefered to take the checks up to
memory_block_action, but offline_pages gets also called from ppc-memtrace code.

Other than that, 

Reviewed-by: Oscar Salvador <osalvador@suse.de>


[1] https://patchwork.kernel.org/patch/10567277/

Thanks
-- 
Oscar Salvador
SUSE L3