On Mon, Jan 25, 2016 at 10:00 PM, 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(a)zytor.com>
> Cc: Ingo Molnar <mingo(a)redhat.com>
> Cc: Rik van Riel <riel(a)redhat.com>
> Cc: Mel Gorman <mgorman(a)suse.de>
> Cc: Jerome Glisse <j.glisse(a)gmail.com>
> Cc: Christoph Hellwig <hch(a)lst.de>
> Cc: Dave Hansen <dave.hansen(a)linux.intel.com>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=110931
> Fixes: 033fbae988fc ("mm: ZONE_DEVICE for "device memory"")
> Reported-by: Sudip Mukherjee <sudipm.mukherjee(a)gmail.com>
It should actually be Reported-by: Mark <markk(a)clara.co.uk>
Can you please test this patch available at https://patchwork.kernel.org/patch/8116991/
in your setup..
Note this patch is on top of 4.5-rc1 and is likely not a suitable for
-stable backport to 4.3/4.4. For 4.3 and 4.4, distributions that want
to support legacy devices should leave ZONE_DEVICE disabled as it is