On Wed, Nov 7, 2018 at 4:00 PM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: > On Wed 07-11-18 15:48:20, Daniel Colascione wrote: >> On Tue, Nov 6, 2018 at 1:05 PM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: >> > otherwise anybody could simply DoS the system >> > by consuming all available pids. >> >> People can do that today using the instrument of terror widely known >> as fork(2). The only thing standing between fork(2) and a full process >> table is RLIMIT_NPROC. > > not really. What else, besides memory consumption and (as you mention below) cgroups? In practice, nobody uses RLIMIT_NPROC, so outside of various container-y namespaced setups, avoidance of system-DoS-through-PID-exhaustion isn't a pressing problem. If you really do care about pid space depletion then you > should use pid cgroup controller. Or that, sure. But since cgroups are optional, the problem with the core model remains. In general, if there's a problem X with the core system API, and you can mitigate X by using a cgroup, X is still a problem.
