3b5bb3a364
In killProcessGroup we currently read cgroup.procs to find processes to kill, send them kill signals until cgroup.procs is empty, then remove the cgroup directory. The cgroup cannot be removed until all processes are dead, otherwise we'll get an EBUSY error from the kernel. There is a race in the kernel where cgroup.procs can read empty even though the cgroup is pinned by processes which are still exiting, and can't be removed yet. [1] Let's use the populated field of cgroup.events instead of an empty cgroup.procs file to determine when the cgroup is removable. In addition to functioning like we expect, this is more efficient because we can poll on cgroup.events instead of retrying kills and rereading cgroup.procs every 5ms which should help reduce CPU contention and cgroup lock contention. It's still possible that it takes longer for a cgroup to become unpopulated than our timeout allows, in which case we will fail to remove the cgroup and leak kernel memory. But this change should help reduce the probability of that happening. [1] https://lore.kernel.org/all/CABdmKX3SOXpcK85a7cx3iXrwUj=i1yXqEz9i9zNkx8mB=ZXQ8A@mail.gmail.com/ Bug: 301871933 Change-Id: If7dcfb331f47e06994c9ac85ed08bbcce18cdad7 |
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