With memmap on memory, some architecture needs more details w.r.t altmap
such as base_pfn, end_pfn, etc to unmap vmemmap memory. Instead of
computing them again when we remove a memory block, embed vmem_altmap
details in struct memory_block if we are using memmap on memory block
feature.

No functional change in this patch

Signed-off-by: Aneesh Kumar K.V <redacted>
---
 drivers/base/memory.c  | 25 +++++++++++-------
 include/linux/memory.h |  8 ++----
 mm/memory_hotplug.c    | 58 +++++++++++++++++++++++++++---------------
 3 files changed, 55 insertions(+), 36 deletions(-)

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index b456ac213610..57ed61212277 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c

@@ -106,6 +106,7 @@ static void memory_block_release(struct device *dev)
 {
 	struct memory_block *mem = to_memory_block(dev);
 
+	WARN_ON(mem->altmap);