Change pointer check method to msync.
Change pointer check method to msync.

The POSIX does not contains /dev/random [1]. Moreover the /dev/random
might not have write permissions. The better way is to use an another
solution which is based on the msync system call [2]. Also this solution
reduces the number of context switching.

[1] -- https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap10.html
[2] -- https://pubs.opengroup.org/onlinepubs/009695399/functions/msync.html

root-mirror/root,root-mirror/root,root-mirror/root,root-mirror/root,olifre/root,olifre/root,root-mirror/root,karies/root,karies/root,root-mirror/root,olifre/root,root-mirror/root,olifre/root,olifre/root,olifre/root,karies/root,root-mirror/root,karies/root,karies/root,karies/root,olifre/root,olifre/root,olifre/root,karies/root,karies/root,karies/root,karies/root,root-mirror/root,root-mirror/root,karies/root,olifre/root,root-mirror/root,olifre/root