[philsnow]

> The proper fix is to keep some PID values allocated. Do not free a PID value until all the children of it have died.

Any fork bomb at all will exhaust the pid graveyard, wouldn't it? You could change pid_t to 64 bits but then the pid graveyard would take a lot of memory in the kernel.

[souprock]

For an actual fork bomb, nothing ends up in the PID graveyard. No process ever dies. The fork bomb by itself is a problem, even without a PID graveyard. Process limits are required to stop a fork bomb.

For other situations, just keep the direct parents. Worst case, that doubles the PID usage.