Comment 70 for bug 1652486

 It might be possible that game fixes something, as i see there was game update 3 days ago with the following mentioned in changelog:

 "Improved several aspects of texture handling for OS X and Linux clients

    This should reduce the rate of "Out of memory" errors for players on high texture settings, especially on level change
    Players still encountering this error can reduce texture quality to medium or lower to greatly improve stability pending further improvements"

 http://store.steampowered.com/news/25022/

 Just wild guessing that this might change something, since game started to be unstable on radeonsi when streaming textures and reduction of mem was introduced last year.