Re: [PATCH 1/2] mem-hotplug: use GFP_HIGHUSER_MOVABLE in, alloc_migrate_target()

[Vlastimil Babka]

On 07/18/2016 07:51 AM, Joonsoo Kim wrote:
> On Fri, Jul 15, 2016 at 10:47:06AM +0800, Xishi Qiu wrote:
> > alloc_migrate_target() is called from migrate_pages(), and the page
> > is always from user space, so we can add __GFP_HIGHMEM directly.
>
> No, all migratable pages are not from user space. For example,
> blockdev file cache has __GFP_MOVABLE and migratable but it has no
> __GFP_HIGHMEM and __GFP_USER.
>
> And, zram's memory isn't GFP_HIGHUSER_MOVABLE but has __GFP_MOVABLE.

Right, and there's also Minchan's series for arbitrary driver page 
migration...

> Thanks.