Re: [PATCH 4/5] mm: fix cache mode of dax pmd mappings

[Andrew Morton]

On Tue, 06 Sep 2016 09:49:41 -0700 Dan Williams <dan.j.williams@xxxxxxxxx> wrote:

> track_pfn_insert() is marking dax mappings as uncacheable.
> 
> It is used to keep mappings attributes consistent across a remapped range.
> However, since dax regions are never registered via track_pfn_remap(), the
> caching mode lookup for dax pfns always returns _PAGE_CACHE_MODE_UC.  We do not
> use track_pfn_insert() in the dax-pte path, and we always want to use the
> pgprot of the vma itself, so drop this call.
> 
> Cc: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
> Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Nilesh Choudhury <nilesh.choudhury@xxxxxxxxxx>
> Reported-by: Kai Zhang <kai.ka.zhang@xxxxxxxxxx>
> Reported-by: Toshi Kani <toshi.kani@xxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>

Changelog fails to explain the user-visible effects of the patch.  The
stable maintainer(s) will look at this and wonder "ytf was I sent
this".

After fixing that, 

Acked-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>