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From: Dan Williams <dan.j.williams@intel.com>
Date: Mon, 7 May 2018 12:29:55 -0700
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Subject: Re: [RFC PATCH v1 0/6] use mm to manage NVDIMM (pmem) zone
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To: Jeff Moyer <jmoyer@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>, Michal Hocko <mhocko@suse.com>, Huaisheng Ye <yehs1@lenovo.com>, linux-nvdimm <linux-nvdimm@lists.01.org>, Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>, chengnt@lenovo.com, Dave Hansen <dave.hansen@intel.com>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, pasha.tatashin@oracle.com, Linux MM <linux-mm@kvack.org>, colyli@suse.de, Johannes Weiner <hannes@cmpxchg.org>, Andrew Morton <akpm@linux-foundation.org>, Sasha Levin <alexander.levin@verizon.com>, Mel Gorman <mgorman@techsingularity.net>, Vlastimil Babka <vbabka@suse.cz>

On Mon, May 7, 2018 at 12:28 PM, Jeff Moyer <jmoyer@redhat.com> wrote:
> Dan Williams <dan.j.williams@intel.com> writes:
[..]
>>> What's the use case?
>>
>> Use NVDIMMs as System-RAM given their potentially higher capacity than
>> DDR. The expectation in that case is that data is forfeit (not
>> persisted) after a crash. Any persistent use case would need to go
>> through the pmem driver, filesystem-dax or device-dax.
>
> OK, but that sounds different from what was being proposed, here.  I'll
> quote from above:
>
>>>>>> But for the critical pages, which we hope them could be recovered
>                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>>>>> from power fail or system crash, we make them to be persistent by
>       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>>>>> storing them to NVM zone.
>
> Hence my confusion.

Yes, now mine too, I overlooked that.