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

Xishi Qiu
2016-07-18T08:01:13Z

On 2016/7/18 13:51, 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.
>

Hi Joonsoo,

So the original code "gfp_t gfp_mask = GFP_USER | __GFP_MOVABLE;"
is not correct?

> And, zram's memory isn't GFP_HIGHUSER_MOVABLE but has __GFP_MOVABLE.
>

Can we distinguish __GFP_MOVABLE or GFP_HIGHUSER_MOVABLE when doing
mem-hotplug?

Thanks,
Xishi Qiu

> Thanks.
>
>
> .
>