On Wed, Aug 26, 2015 at 09:39:18PM +0000, Williams, Dan J wrote:
On Wed, 2015-08-26 at 14:46 +0200, Christoph Hellwig wrote:
> On Tue, Aug 25, 2015 at 09:28:13PM -0400, Dan Williams wrote:
> > Given that:
> > 1/ device ->remove() can not be failed
> > 2/ a pmem device may be unbound at any time
> > 3/ we do not know what other parts of the kernel are actively using a
> > 'struct page' from devm_memremap_pages()
> > ...provide a facility for active usages of device memory to block pmem
> > device unbind. With a percpu_ref it should be feasible to take a
> > reference on a per-I/O or other high frequency basis.
> Without a caller of get_page_map this is just adding dead code. I'd
> suggest to group it in a series with that caller.
Agreed, we can drop this until the first user arrives.
> Also if the page_map gets exposed in a header the name is a bit too generic.
> memremap_map maybe?
Done, and in the patch below I hide the internal implementation details
of page_map in kernel/memremap.c and only expose the percpu_ref in the
Yes, that looks good once we're getting the users for it.