[CRIU] [PATCH] Skip restoring certain cgroup root directories when using full mode

[Hui Kang]

On Thu, Aug 27, 2015 at 7:01 AM, Andrew Vagin <avagin at gmail.com> wrote:
> On Wed, Aug 26, 2015 at 11:12:02PM -0400, Hui Kang wrote:
>> On Wed, Aug 26, 2015 at 12:27 AM, Andrew Vagin <avagin at gmail.com> wrote:
>> > On Tue, Aug 25, 2015 at 10:25:02PM -0400, Hui Kang wrote:
>> >>
>> >> Hi, Pavel
>> >> I still have difficulty in producing the bug you described. I have
>> >> /sys/fs/cgroup/cpuset (which is the root) and /sys/fs/cgroup/cpuset/A.
>> >> I have added task 1001 to the root and 1002 to
>> >> /sys/fs/cgroup/cpuset/A. The patch has no problem in restoring the the
>> >> task in /A.
>> >>
>> >> If this is the not nested case you described, could you give more
>> >> detailed about the case you think of? Thanks.
>> >
>> > I think I've reproduced this bug:
>> > https://asciinema.org/a/cv3qlitwvvt2guyi2woaok056
>>
>> Hi, Andew,
>> I created my own script to reproduce the bug of not restoring cpu
>> share. The script is
>>
>> #! /bin/bash
>> set -e -x
>> echo $$
>> mkdir -p /sys/fs/cgroup/cpu/A
>> echo 512 > /sys/fs/cgroup/cpu/A/cpu.shares
>> sleep 1000 &
>> echo $! > /sys/fs/cgroup/cpu/A/tasks
>> wait
>> [ `cat /sys/fs/cgroup/cpu/A/cpu.shares` -ne 512 ] && echo FAIL
>>
>> It will create two pid, say the first is 18001 and the second is 18002.
>> When I run
>>
>> criu dump -t 18001 -vvvv --log-file dump.log -j  --manage-cgroup=ful
>>
>> It gives me the error
>>
>> Dumping file-locks
>> (00.028444)
>> (00.028451) Dumping pstree (pid: 18672)
>> (00.028458) ----------------------------------------
>> (00.028466) Process: 18672(18672)
>> (00.028506) Process: 18674(18674)
>> (00.028516) ----------------------------------------
>> (00.028619) Error (cgroup.c:807): cg: Non supported sub-cgroups found
>> (00.028961) Unlock network
>> (00.028983) Unfreezing tasks into 1
>> (00.028994) Unseizing 18672 into 1
>> (00.029081) Unseizing 18674 into 1
>>
>> I am using the criu from git. Do you know why this happens? Thanks.
>
> I have seen this error too.
> CRIU and the root task live in the same set of cgroups.
> CRIU expects that all task should live in this set of cgroups.
> Pavel, could you explain this behaviour?
>

Hi, Andrew,
I am just curious how you bypass this in your video demo : )

- Hui

>         /*
>          * Check whether root task lives in its own set as compared
>          * to criu. If yes, we should not dump anything, but make
>          * sure no other sets exist. The latter case can be supported,
>          * but requires some trickery and is hardly needed at the
>          * moment.
>          */
>
>         if (root_cgset == criu_cgset) {
>                 if (!list_is_singular(&cg_sets)) {
>                         pr_err("Non supported sub-cgroups found\n");
>                         return -1;
>                 }
>
>
>>
>> - Hui
>>
>> >
>> >>
>> >> - Hui
>> >>
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