On 25/01/2019 17:37, Tejun Heo wrote: > On Fri, Jan 25, 2019 at 08:52:11AM +0100, Arkadiusz Miśkiewicz wrote: >> On 24/01/2019 12:21, Arkadiusz Miśkiewicz wrote: >>> On 17/01/2019 14:17, Arkadiusz Miśkiewicz wrote: >>>> On 17/01/2019 13:25, Aleksa Sarai wrote: >>>>> On 2019-01-17, Arkadiusz Miśkiewicz <a.miskiewicz@xxxxxxxxx> wrote: >>>>>> Using kernel 4.19.13. >>>>>> >>>>>> For one cgroup I noticed weird behaviour: >>>>>> >>>>>> # cat pids.current >>>>>> 60 >>>>>> # cat cgroup.procs >>>>>> # >>>>> >>>>> Are there any zombies in the cgroup? pids.current is linked up directly >>>>> to __put_task_struct (so exit(2) won't decrease it, only the task_struct >>>>> actually being freed will decrease it). >>>>> >>>> >>>> There are no zombie processes. >>>> >>>> In mean time the problem shows on multiple servers and so far saw it >>>> only in cgroups that were OOMed. >>>> >>>> What has changed on these servers (yesterday) is turning on >>>> memory.oom.group=1 for all cgroups and changing memory.high from 1G to >>>> "max" (leaving memory.max=2G limit only). >>>> >>>> Previously there was no such problem. >>>> >>> >>> I'm attaching reproducer. This time tried on different distribution >>> kernel (arch linux). >>> >>> After 60s pids.current still shows 37 processes even if there are no >>> processes running (according to ps aux). >> >> >> The same test on 5.0.0-rc3-00104-gc04e2a780caf and it's easy to >> reproduce bug. No processes in cgroup but pids.current reports 91. > > Can you please see whether the problem can be reproduced on the > current linux-next? > > git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git I can reproduce on next (5.0.0-rc3-next-20190125), too: [root@xps test]# python3 cg.py Created cgroup: /sys/fs/cgroup/test_2501 Start: pids.current: 0 Start: cgroup.procs: 0: pids.current: 65 0: cgroup.procs: 1: pids.current: 44 1: cgroup.procs: 2: pids.current: 44 2: cgroup.procs: 3: pids.current: 44 3: cgroup.procs: 4: pids.current: 44 4: cgroup.procs: 5: pids.current: 44 5: cgroup.procs: 6: pids.current: 44 6: cgroup.procs: 7: pids.current: 44 7: cgroup.procs: 8: pids.current: 44 8: cgroup.procs: 9: pids.current: 44 9: cgroup.procs: 10: pids.current: 44 10: cgroup.procs: 11: pids.current: 44 11: cgroup.procs: [root@xps test]# uname -a Linux xps 5.0.0-rc3-next-20190125 #2 SMP PREEMPT Fri Jan 25 19:11:40 CET 2019 x86_64 Intel(R)_Core(TM)_i9-8950HK_CPU_@_2.90GHz PLD Linux [root@xps test]# mount |grep cgroup2 cgroup2 on /sys/fs/cgroup type cgroup2 (rw,nosuid,nodev,noexec,relatime) I'm booting kernel with cgroup_no_v1=all -- Arkadiusz Miśkiewicz, arekm / ( maven.pl | pld-linux.org )
