Re: [PATCH] selftests/cgroup: Fix intermittent test_cgfreezer_ptrace test failures

[Waiman Long <longman@redhat.com>]

On 7/14/26 6:09 PM, Tejun Heo wrote:
> Hello, Waiman.
>
>> +	usleep(1000);
>>   	if (cg_check_frozen(cgroup, true))
>>   		goto cleanup;
> A fixed 1ms sleep only hides the race. On a loaded machine or a slow arch
> (you mention ppc64) the refreeze can take longer than 1ms, and the test
> reads the unfrozen state and fails anyway.
>
> The freezer test already has a way to wait for this properly.
> cg_prepare_for_wait() sets up an inotify watch on cgroup.events and
> cg_wait_for() blocks until it changes. cg_enter_and_wait_for_frozen() shows
> the pattern: loop cg_wait_for() then cg_check_frozen(). The cgroup always
> ends up frozen, so looping until cg_check_frozen() reports frozen is
> reliable and doesn't depend on timing.
>
> Can you respin using that instead of usleep()?
>
> Also, temporaily -> temporarily, in both the changelog and the comment.
>
> Thanks.

Thanks for the suggestion. Will revise the patch as suggested.

Cheers,
Longman