Backup/Restore Users/Passwords/Privileges
The 'mysql' database contains users/privileges/passwords. So take the dump of mysql database along with other databases
mysqldump [options] --all-databases > all_databases_dump.sql
mysqldump -u root -p mysql user > user_table_dump.sql
These mysql database tables contain grant information
user: User accounts, global privileges, and other non-privilege columns.
db: Database-level privileges.
tables_priv: Table-level privileges.
columns_priv: Column-level privileges.
procs_priv: Stored procedure and function privileges.
After restoring cross check with
select Host, user, password from user ;
SHOW GRANTS FOR 'user'@'localhost';