Re: [RFC PATCH] mm: support CONFIG_ZONE_DEVICE + CONFIG_ZONE_DMA

[Sudip Mukherjee]

On Mon, Jan 25, 2016 at 04:06:40PM -0800, Dan Williams wrote:
> It appears devices requiring ZONE_DMA are still prevalent (see link
> below).  For this reason the proposal to require turning off ZONE_DMA to
> enable ZONE_DEVICE is untenable in the short term.  We want a single
> kernel image to be able to support legacy devices as well as next
> generation persistent memory platforms.
> 
> Towards this end, alias ZONE_DMA and ZONE_DEVICE to work around needing
> to maintain a unique zone number for ZONE_DEVICE.  Record the geometry
> of ZONE_DMA at init (->init_spanned_pages) and use that information in
> is_zone_device_page() to differentiate pages allocated via
> devm_memremap_pages() vs true ZONE_DMA pages.  Otherwise, use the
> simpler definition of is_zone_device_page() when ZONE_DMA is turned off.
> 
> Note that this also teaches the memory hot remove path that the zone may
> not have sections for all pfn spans (->zone_dyn_start_pfn).
> 
> A user visible implication of this change is potentially an unexpectedly
> high "spanned" value in /proc/zoneinfo for the DMA zone.
> 
> Cc: H. Peter Anvin <hpa@xxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Jerome Glisse <j.glisse@xxxxxxxxx>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=110931
> Fixes: 033fbae988fc ("mm: ZONE_DEVICE for "device memory"")
> Reported-by: Sudip Mukherjee <sudipm.mukherjee@xxxxxxxxx>

It should actually be Reported-by: Mark <markk@xxxxxxxxxxx>

Hi Mark,
Can you please test this patch available at https://patchwork.kernel.org/patch/8116991/
in your setup..

regards
sudip