yum install - Cannot allocate memory

skipping unreadable repository '/etc/yum.repos.d/CentOS-Vault.repo'

Skipping unreadable repository '/etc/yum.repos.d/CentOS-fasttrack.repo'

Loading mirror speeds from cached hostfile

Resolving Dependencies

--> Running transaction check

---> Package openssl.x86_64 1:1.0.2k-8.el7 will be installed

--> Processing Dependency: make for package: 1:openssl-1.0.2k-8.el7.x86_64

--> Running transaction check

---> Package make.x86_64 1:3.82-23.el7 will be installed

[Errno 12] Cannot allocate memory: '//var/lib/yum/rpmdb-indexes/version.tmp'

# yum clean all
# rm -f /var/lib/rpm/__db*
# rpm --rebuilddb