Linux bugs: Life cycle, resolution and architectural analysis

Efforts to improve application reliability can be irrelevant if the reliability of the underlying operating system on which the application resides is not seriously considered. An important first step in improving the reliability of an operating system is to gain insights into why and how the bugs originate, contributions of the different modules to the bugs, their distribution across severities, the different ways in which the bugs may be resolved and the impact of bug severities on their resolution times. To acquire this insight, we conducted an extensive analysis of the publicly available bug data on the Linux kernel over a period of seven years. We also justify and explain the statistical bug occurrence trends observed from the data, using the architecture of the Linux kernel as an anchor. The statistical analysis of the Linux bug data suggests that the Linux kernel may draw significant benefits from the continual reliability improvement efforts of its developers. These efforts, however, are disproportionately targeted towards popular configurations and hardware platforms, due to which the reliability of these configurations may be better than those that are not commonly used. Thus, a key finding of our study is that it may be prudent to restrict to using common configurations and platforms when using open source systems such as Linux in applications with stringent reliability expectations. Finally, our study of the architectural properties of the bugs suggests that the dependence among the modules rather than the unreliabilities of the individual modules is the primary cause of the bugs and their impact on system reliability.