Re: [PATCH 0/2] Don't show PF_IO_WORKER in /proc/<pid>/task/

[Jens Axboe <axboe@kernel.dk>]

On 3/25/21 2:40 PM, Oleg Nesterov wrote:
> On 03/25, Eric W. Biederman wrote:
>>
>> So looking quickly the flip side of the coin is gdb (and other
>> debuggers) needs a way to know these threads are special, so it can know
>> not to attach.
> 
> may be,
> 
>> I suspect getting -EPERM (or possibly a different error code) when
>> attempting attach is the right was to know that a thread is not
>> available to be debugged.
> 
> may be.
> 
> But I don't think we can blame gdb. The kernel changed the rules, and this
> broke gdb. IOW, I don't agree this is gdb bug.

Right, that's what I was getting at too - and it's likely not just gdb.
We have to ensure that we don't break this use case, which seems to
imply that we:

1) Just make it work, or
2) Make them hidden in such a way that gdb doesn't see them, but
   regular tooling does

#2 seems fraught with peril, and maybe not even possible.

-- 
Jens Axboe