On Tue, Oct 03, 2017 at 05:53:15PM +0200, Oleg Nesterov wrote: > On 10/02, Andrew Morton wrote: > > > > From: Alexey Dobriyan <adobri...@gmail.com> > > Subject: pid: delete RESERVED_PIDS > > > > RESERVED_PIDS had a noble goal: to protect root from PID exhaustion since > > at least ~2.5.40 > > I am just curious, where did you find the change which documents this goal?
Now that you asked, I'm not exactly sure. :-( Please don't tell it is for some kind of stupid userspace which assumed low numbers are kernel threads. > > except it never did that because there was no capability > > or uid checks. > > > > Allow small pids to be allocated after rollover, there is nothing sacred > > about them. > > > > Resource exhaustion should be handled by rlimits and/or kernel memory > > accounting. > > I won't argue, but I always thought that the only purpose of RESERVED_PIDS > is to make the system/kernek daemons started at boot time more "visible" in > /usr/bin/ps output. They will be first in line naturally: kthreadd + init execute first and rarely exit.
