On Mon 09-10-17 13:51:47, Pavel Tatashin wrote:

Hi Will,

I can go back to that approach, if Michal OK with it. But, that would
mean that I would need to touch every single architecture that
implements vmemmap_populate(), and also pass flags at least through
these functions on every architectures (some have more than one
decided by configs).:

vmemmap_populate()
vmemmap_populate_basepages()
vmemmap_populate_hugepages()
vmemmap_pte_populate()
__vmemmap_alloc_block_buf()
alloc_block_buf()
vmemmap_alloc_block()

IMO, while I understand that it looks strange that we must walk page
table after creating it, it is a better approach: more enclosed as it
effects kasan only, and more universal as it is in common code.

While I understand that gfp mask approach might look better at first
sight this is by no means a general purpose API so I would rather be
pragmatic and have a smaller code footprint than a more general
interface. Kasan is pretty much a special case and doing a one time
initialization 2 pass thing is imho acceptable. If this turns out to be
impractical in future then let's fix it up but right now I would rather
go a simpler path.
-- 
Michal Hocko
SUSE Labs