mm, doc: cleanup and clarify munmap behavior for hugetlb memory

munmap(2) of hugetlb memory requires a length that is hugepage aligned,
otherwise it may fail.  Add this to the documentation.

This also cleans up the documentation and separates it into logical units:
one part refers to MAP_HUGETLB and another part refers to requirements for
shared memory segments.

Signed-off-by: David Rientjes <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Davide Libenzi <[email protected]>
Cc: Luiz Capitulino <[email protected]>
Cc: Shuah Khan <[email protected]>
Acked-by: Hugh Dickins <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Joern Engel <[email protected]>
Cc: Jianguo Wu <[email protected]>
Cc: Eric B Munson <[email protected]>
Cc: Michael Ellerman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions