Re: [RFC v2 0/2] Do not touch pages in remove_memory path

From: Oscar Salvador
Date: Tue Aug 28 2018 - 07:47:15 EST

On Fri, Aug 17, 2018 at 05:41:25PM +0200, Oscar Salvador wrote:
> From: Oscar Salvador <osalvador@xxxxxxx>
> The main difficulty I faced here was in regard of HMM/devm, as it really handles
> the hot-add/remove memory particulary, and what is more important,
> also the resources.
> I really scratched my head for ideas about how to handle this case, and
> after some fails I came up with the idea that we could check for the
> res->flags.
> Memory resources that goes through the "official" memory-hotplug channels
> have the IORESOURCE_SYSTEM_RAM flag.
> HMM/devm, on the other hand, request and release the resources
> through devm_request_mem_region/devm_release_mem_region, and
> these resources do not contain the IORESOURCE_SYSRAM flag.
> So what I ended up doing is to check for IORESOURCE_SYSRAM
> in release_mem_region_adjustable.
> If we see that a resource does not have such a flag, we know that
> we are dealing with a resource coming from HMM/devm, and so,
> we do not need to do anything as HMM/dev will take care of that part.

Jerome/Dan, now that the merge window is closed, and before sending the RFCv3, could you please check
this and see if you see something that is flagrant wrong? (about devm/HMM)

If you prefer I can send v3 spliting up even more.
Maybe this will ease the review.

Oscar Salvador