Over the past 6 months I've been running static analysis on linux-next with CoverityScan on a regular basis (to find new issues and fix some of them) as well as keeping a record of the defect count.
Since the beginning of September over 2000 defects have been eliminated by a host of upstream developers and the steady downward trend of outstanding issues is good to see. A proportion of the outstanding defects are false positives or issues where the code is being overly zealous, for example, bounds checking where some conditions can never happen. Considering there are millions of lines of code, the defect rate is about average for such a large project.
I plan to keep the static analysis running long term and I'll try and post stats every 6 months or so to see how things are progressing.