Wolfram Alpha tells me that that mass
≈ 0.35 × estimated mass of all oil produced since 1850 (upper limit) ( 1×10^11 t )
You're forgetting two things here: Oxygen and coal. While there are other sources of this apparent discrepancy, these are the two main sources of your skepticism.
Carbon dioxide comprises one molecule of carbon and two of oxygen. By mass, carbon dioxide is 27.3% carbon and 72.7% oxygen. The other factor is coal. In 2011, only a third (33.2%) of the carbon dioxide produced by mankind came from the burning of oil-related products. About 63% of the remaining 2/3 came from burning coal. Using these two qualifier (12/44 and 0.332) to refine the Wolfram Alpha query in the question yields a more relevant comparison:
≈ 0.76 × world oil production mass in 2004 (≈ 4.15×10^12 kg )
Not quite 100%, for two reasons. Some oil is used for purposes other than producing carbon dioxide, and some of the mass of oil is in the form of hydrogen.
Was the total CO2 added to the atmosphere in 2011 (or a similar year)?
Yes. This amount is consistent with other estimates. For example, the Emissions Database for Global Atmospheric Research says global emissions of carbon dioxide were 33865904 kilotons in 2010, 35865277 in 2013. (Note: Those overly precise are exactly what's on that web site. I've left them as-is.) Converting to customary units yields 37.3 billion tons for 2010, 39.5 billion tons for 2013. The Global Carbon Project says that 9.5±0.5 petagrams of carbon were released in 2011; multiplying by 44/12 to get the CO2 equivalent and converting to short tons yields 38.4 billion tons. Several other sources provide estimates consistent with these.