memory-hotplug: add sysfs valid_zones attribute

Currently memory-hotplug has two limits:

1. If the memory block is in ZONE_NORMAL, you can change it to
   ZONE_MOVABLE, but this memory block must be adjacent to ZONE_MOVABLE.

2. If the memory block is in ZONE_MOVABLE, you can change it to
   ZONE_NORMAL, but this memory block must be adjacent to ZONE_NORMAL.

With this patch, we can easy to know a memory block can be onlined to
which zone, and don't need to know the above two limits.

Updated the related Documentation.

[[email protected]: use conventional comment layout]
[[email protected]: fix build with CONFIG_MEMORY_HOTREMOVE=n]
[[email protected]: remove unused local zone_prev]
Signed-off-by: Zhang Zhen <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Toshi Kani <[email protected]>
Cc: Yasuaki Ishimatsu <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Wang Nan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions