The Rock's mom is thanking the giant SUV her son bought her for saving her life in a head-on collision -- and amazingly holds no grudges against the woman who hit her.
Ata Maivia-Johnson tells TMZ ... "As much as I'd like to lay the Samoan smackdown on the drunk driver that crashed into us, I've already forgiven her."
Ata and Dwayne's cousin Lina Fanene were driving home last week when the other driver plowed into their Escalade.
Ata added, "By the grace of God and my big heavy strong car, we are alive today to hug our loved ones once again."
The driver has been charged with a DUI in the incident.