yum update
yum install yum-plugin-downloadonly
wget
http://mirror.centos.tld/centos/x.x/os/x86_64/Packages/kernel-2.6.32-xxx.el6.x86_64.rpmrpm -qa | sort | grep 686 > lists.txt
replace i686 to x86_64 in lists.txt
rpm -Uhv --force --ignorearch kernel-2.6.32-xxx.el6.x86_64.rpm
change /grub/menu.lst
reboot
yum install --downloadonly --downloaddir=./ $(cat lists.txt|xargs)
rpm -iv --force *.rpm
cd /var/lib/rpm
rm __db.*
rpm --rebuilddb
rpm -iv *.rpm
reboot