On 1/18/21 6:43 PM, Anshuman Khandual wrote:

From: David Hildenbrand <redacted>

Right now, we only check against MAX_PHYSMEM_BITS - but turns out there
are more restrictions of which memory we can actually hotplug, especially
om arm64 or s390x once we support them: we might receive something like
-E2BIG or -ERANGE from add_memory_driver_managed(), stopping device
operation.

So, check right when initializing the device which memory we can add,
warning the user. Try only adding actually pluggable ranges: in the worst
case, no memory provided by our device is pluggable.

In the usual case, we expect all device memory to be pluggable, and in
corner cases only some memory at the end of the device-managed memory
region to not be pluggable.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Wei Yang <redacted>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: catalin.marinas@arm.com
Cc: teawater <redacted>
Cc: Anshuman Khandual <redacted>
Cc: Pankaj Gupta <redacted>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: hca@linux.ibm.com
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: David Hildenbrand <redacted>
Signed-off-by: Anshuman Khandual <redacted>

Hello David,

As your original patch was in the RFC state, I have just maintained
the same here as well. But once you test this patch along with the
new series, please do let me know if this needs to be converted to
a normal PATCH instead. Thank you.

- Anshuman

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