Davinci Resolve is what Company 3 uses (The Martian, Spectre, Jurassic World, etc). It's available on Mac and Linux, but the big shops use the Linux version as they can expand it allowing for more real time nodes.
Baselight is another major platform for color grading that runs on Linux.
I worked for a company that performed stereoscopic conversion for Hollywood films. Their primary tool was NUKE [1] running on Linux. It's also available for Mac and Windows, but because NUKE encompassed their entire workflow, the underlying OS wasn't especially important.
