- Add documentation for EBUSY.

- Remove EIO.
 - Add a cross reference to mlock(2).

lib/libc/sys/msync.2

@@ -78,6 +78,9 @@ The
 system call
 will fail if:
 .Bl -tag -width Er
+.It Bq Er EBUSY
+Some or all of the pages in the specified region are locked and
+MS_INVALIDATE is specified.
 .It Bq Er EINVAL
 The
 .Fa addr
@@ -94,12 +97,11 @@ The
 argument
 was both MS_ASYNC and MS_INVALIDATE.
 Only one of these flags is allowed.
-.It Bq Er EIO
-An I/O error occurred while writing to the file system.
 .El
 .Sh SEE ALSO
 .Xr madvise 2 ,
 .Xr mincore 2 ,
+.Xr mlock 2 ,
 .Xr mprotect 2 ,
 .Xr munmap 2
 .Sh HISTORY