DML currently not allowed

I have 2 VF pages. When I create an Opportunity some values are supposed to be carried over to VFpage1 and VFpage2 is supposed to be a summation of the information in VFpage1. The problem I am running into is if I create a new opportunity and then go straight to VFpage2, the summation information is not updated. However if I load VFpage1 and then load VFpage2 the information is passed through and summed up correctly.

I found that VFpage1's header contains action="{!updateMethod}". I believe it is this updateMethod that needs to be run before VFpage2 will have the correct information.

Is there anyway to call VFpage1.VFpage1ControllerClass.updateMethod from VFPage2?

When I add VFpage1ControllerClass.updateMethod to VFpage2ControllerClass I get the DML error.