On 2018-06-14, Ivan Zahariev <famzah@xxxxxxxxxxx> wrote: > I posted a kernel bug about this a month ago but it did not receive any > attention: https://bugzilla.kernel.org/show_bug.cgi?id=199713 I believe that very few people watch the kernel bugzilla -- it's almost always better to send a mail to LKML (speaking of which, you should always include <linux-kernel@xxxxxxxxxxxxxxx> in Cc). > I've tested this on 4.14.27 and 4.4.0-124-generic Ubuntu. > > If I start a couple of processes which exit very quickly (like a simple Bash > script with many commands in it), the reported value in "pids.current" is > not updated immediately when processes exit. This leads to too many > processes incorrectly accounted in "pids.current" which hits the "pids.max" > prematurely. One possible reason for this might be related to zombie processes. cgroup.procs doesn't include any zombie processes (tasks are removed when they exit(2)), but the pids controller does track zombies (tasks are removed when the 'struct task' is put'd). This could explain why there's a discrepancy which clears itself up after a short period of time -- though I am not sure that your reproducer will actually produce zombies (I only took a quick look at it). > The "memory" controller, for example, works as expected and does not suffer > from this asynchronous lag. I'm not sure what makes the memory controller and the pids controller comparable in this aspect -- there is no "pids.current" for the memory controller. -- Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH <https://www.cyphar.com/>
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