Hi, Stefan reports that attaching to a task with io_uring will leave gdb very confused and just repeatedly attempting to attach to the IO threads, even though it receives an -EPERM every time. This patchset proposes to skip PF_IO_WORKER threads as same_thread_group(), except for accounting purposes which we still desire. We also skip listing the IO threads in /proc/<pid>/task/ so that gdb doesn't think it should stop and attach to them. This makes us consistent with earlier kernels, where these async threads were not related to the ring owning task, and hence gdb (and others) ignored them anyway. Seems to me that this is the right approach, but open to comments on if others agree with this. Oleg, I did see your messages as well on SIGSTOP, and as was discussed with Eric as well, this is something we most certainly can revisit. I do think that the visibility of these threads is a separate issue. Even with SIGSTOP implemented (which I did try as well), we're never going to allow ptrace attach and hence gdb would still be broken. Hence I'd rather treat them as separate issues to attack. -- Jens Axboe
