mmap: handle mlocked pages during map, remap, unmap

mmap: handle mlocked pages during map, remap, unmap

Originally by Nick Piggin <[email protected]>

Remove mlocked pages from the LRU using "unevictable infrastructure"
during mmap(), munmap(), mremap() and truncate().  Try to move back to
normal LRU lists on munmap() when last mlocked mapping removed.  Remove
PageMlocked() status when page truncated from file.

[[email protected]: cleanup]
[[email protected]: fix double unlock_page()]
[[email protected]: split LRU: munlock rework]
[[email protected]: mlock: fix __mlock_vma_pages_range comment block]
[[email protected]: remove bogus kerneldoc token]
Signed-off-by: Nick Piggin <[email protected]>
Signed-off-by: Lee Schermerhorn <[email protected]>
Signed-off-by: Rik van Riel <[email protected]>
Signed-off-by: KOSAKI Motohiro <[email protected]>
Signed-off-by: KAMEZAWA Hiroyuki <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>