page_alloc: add movable_memmap kernel parameter

page_alloc: add movable_memmap kernel parameter

Add functions to parse movablemem_map boot option.  Since the option
could be specified more then once, all the maps will be stored in the
global variable movablemem_map.map array.

And also, we keep the array in monotonic increasing order by start_pfn.
And merge all overlapped ranges.

[[email protected]: improve comment]
[[email protected]: checkpatch fixes]
[[email protected]: remove unneeded parens]
Signed-off-by: Tang Chen <[email protected]>
Signed-off-by: Lai Jiangshan <[email protected]>
Reviewed-by: Wen Congyang <[email protected]>
Tested-by: Lin Feng <[email protected]>
Cc: Wu Jianguo <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>