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Date: Thu, 8 Sep 2016 15:49:31 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-nvdimm@ml01.01.org, Toshi Kani <toshi.kani@hpe.com>,
        Matthew Wilcox <mawilcox@microsoft.com>,
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        Ross Zwisler <ross.zwisler@linux.intel.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Kai Zhang <kai.ka.zhang@oracle.com>
Subject: Re: [PATCH v2 1/2] mm: fix cache mode of dax pmd mappings
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On Wed, 07 Sep 2016 15:26:14 -0700 Dan Williams <dan.j.williams@intel.com> wrote:

> track_pfn_insert() in vmf_insert_pfn_pmd() is marking dax mappings as
> uncacheable rendering them impractical for application usage.  DAX-pte
> mappings are cached and the goal of establishing DAX-pmd mappings is to
> attain more performance, not dramatically less (3 orders of magnitude).
> 
> track_pfn_insert() relies on a previous call to reserve_memtype() to
> establish the expected page_cache_mode for the range.  While memremap()
> arranges for reserve_memtype() to be called, devm_memremap_pages() does
> not.  So, teach track_pfn_insert() and untrack_pfn() how to handle
> tracking without a vma, and arrange for devm_memremap_pages() to
> establish the write-back-cache reservation in the memtype tree.

Acked-by: Andrew Morton <akpm@linux-foundation.org>

I'll grab [2/2].