Hi Florian,

thanks for your message. Please, find the replies in-line.

On Wed, Mar 29, 2017 at 05:40:02PM -0700, Florian Fainelli wrote:

While the "hack" that sets/clears NOMAP in order for pfn_valid() to
return false/true when appropriate during __add_pages() definitively
does seem to work to probe the memory section, don't you also hit the
same warning when you try to online that memory section in
pages_correctly_reserved() once you have cleared the NOMAP flag?

Before arch_add_memory returns, we clear the nomap flag on the blocks,
so that pfn_valid will return true when executing on the corresponding
pages. This means that the condition in pages_correctly_reserved in
drivers/base/memory.c:

	if (WARN_ON_ONCE(!pfn_valid(pfn)))

will evaluate to false, so no warning should be issued, and the function
should continue to execute as expected.

Is it that you were referring to or did I miss the point?

I will definitively give this a try on ARM64 since I need to get it
working there.

Thanks a lot, any help in testing is really appreciated. 
 

Do you mind posting a non-RFC patch?

We should release the hot-remove code that myself and Maciej have been
working on very soon (say, around one week); the plan is to rebase
everything and release hot-add and hot-remove as a single patch series
(including Scott's original patches and our hot-add patches). If you
can wait until then, we will probably minimize entropy; otherwise we
can also re-post the hot-add patches earlier and separately.
 
Thanks and regards,
Andrea