kernel, resource: check for IORESOURCE_SYSRAM in release_mem_region_adjustable

This is a preparation for the next patch.

Currently, we only call release_mem_region_adjustable() in __remove_pages
if the zone is not ZONE_DEVICE, because resources that belong to HMM/devm
are being released by themselves with devm_release_mem_region.

Since we do not want to touch any zone/page stuff during the removing of
the memory (but during the offlining), we do not want to check for the
zone here.  So we need another way to tell release_mem_region_adjustable()
to not realease the resource in case it belongs to HMM/devm.

HMM/devm acquires/releases a resource through
devm_request_mem_region/devm_release_mem_region.

These resources have the flag IORESOURCE_MEM, while resources acquired by
hot-add memory path (register_memory_resource()) contain
IORESOURCE_SYSTEM_RAM.

So, we can check for this flag in release_mem_region_adjustable, and if
the resource does not contain such flag, we know that we are dealing with
a HMM/devm resource, so we can back off.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Oscar Salvador <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Reviewed-by: Pavel Tatashin <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Jonathan Cameron <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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