On Thu 14-05-15 12:31:49, Cyril Hrubis wrote:
[...]
> Looking at the code, it does two more things here:
>
> echo $pid > tasks
> kill -s USR1 $pid 2> /dev/null
>
> Sending SIGUSR1 to the memcg_process causes it to repeat the allocation
> that has been passed to it by the command line parameters.
>
> So my guess is that it expect the force_empty to fail if the process has
> allocated some memory after it has been moved to the current cgroup.
force_empty fails if the memcg cannot be reclaimed down to 0. The memory
charged after the task has moved to the group is easily reclaimable so
I do not see any reason why we would fail here.
> The previous testcases does exactly this but moves the process to the
> parent with:
>
> echo $pid > ../tasks
>
> Before it tries the force_empty and expects it to succeed.
>
> Was this some old implementation limitation that has been lifted
> meanwhile?
OK, now I remember... f61c42a7d911 ("memcg: remove tasks/children test
from mem_cgroup_force_empty()") which goes back to 3.16. So the test
case is invalid.
--
Michal Hocko
SUSE Labs
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