Re: Tasks stuck on exit(2) with 5.15.6

[Jens Axboe <axboe@kernel.dk>]

On 12/3/21 4:52 AM, Florian Fischer wrote:
> Hi Jens, 
> 
>> Thanks for the bug report, and I really appreciate including a reproducer.
>> Makes everything so much easier to debug.
> 
> Glad I could help :)
> 
>> Are you able to compile your own kernels? Would be great if you can try
>> and apply this one on top of 5.15.6.
>>
>>
>> diff --git a/fs/io-wq.c b/fs/io-wq.c
>> index 8c6131565754..e8f77903d775 100644
>> --- a/fs/io-wq.c
>> +++ b/fs/io-wq.c
>> @@ -711,6 +711,13 @@ static bool io_wq_work_match_all(struct io_wq_work *work, void *data)
>>  
>>  static inline bool io_should_retry_thread(long err)
>>  {
>> +	/*
>> +	 * Prevent perpetual task_work retry, if the task (or its group) is
>> +	 * exiting.
>> +	 */
>> +	if (fatal_signal_pending(current))
>> +		return false;
>> +
>>  	switch (err) {
>>  	case -EAGAIN:
>>  	case -ERESTARTSYS:
> 
> With your patch on top of 5.15.6 I can no longer reproduce stuck processes.
> Neither with our software nor with the reproducer.
> I ran both a hundred times and both terminated immediately without unexpected CPU usage.
> 
> Tested-by: Florian Fischer <florian.fl.fischer@fau.de>

Great, thanks for testing!

-- 
Jens Axboe