[dm-devel] [PATCH] vmalloc: introduce vmap_pfn for persistent memory

[Christoph Hellwig]

On Tue, Nov 07, 2017 at 05:03:11PM -0500, Mikulas Patocka wrote:
> Hi
> 
> I am developing a driver that uses persistent memory for caching. A 
> persistent memory device can be mapped in several discontiguous ranges.
> 
> The kernel has a function vmap that takes an array of pointers to pages 
> and maps these pages to contiguous linear address space. However, it can't 
> be used on persistent memory because persistent memory may not be backed 
> by page structures.
> 
> This patch introduces a new function vmap_pfn, it works like vmap, but 
> takes an array of pfn_t - so it can be used on persistent memory.

How is cache flushing going to work for this interface assuming
that your write to/from the virtual address and expect it to be
persisted on pmem?