Re: [PATCH -next] mm/hotplug: skip bad PFNs from pfn_to_online_page()

[Aneesh Kumar K.V]

On 6/14/19 10:06 PM, Dan Williams wrote:
> On Fri, Jun 14, 2019 at 9:26 AM Aneesh Kumar K.V
> <aneesh.kumar@xxxxxxxxxxxxx> wrote:

> > Why not let the arch
> > arch decide the SUBSECTION_SHIFT and default to one subsection per
> > section if arch is not enabled to work with subsection.
>
> Because that keeps the implementation from ever reaching a point where
> a namespace might be able to be moved from one arch to another. If we
> can squash these arch differences then we can have a common tool to
> initialize namespaces outside of the kernel. The one wrinkle is
> device-dax that wants to enforce the mapping size,

The fsdax have a much bigger issue right? The file system block size is 
the same as PAGE_SIZE and we can't make it portable across archs that 
support different PAGE_SIZE?

-aneesh