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From: ebiederm@xmission.com (Eric W. Biederman)
To: Oleg Nesterov <oleg@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	io-uring <io-uring@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Stefan Metzmacher <metze@samba.org>
Subject: Re: [PATCH 0/2] Don't show PF_IO_WORKER in /proc/<pid>/task/
Date: Thu, 25 Mar 2021 15:48:59 -0500	[thread overview]
Message-ID: <m135wj0xj8.fsf@fess.ebiederm.org> (raw)
In-Reply-To: <20210325204014.GD28349@redhat.com> (Oleg Nesterov's message of "Thu, 25 Mar 2021 21:40:15 +0100")

Oleg Nesterov <oleg@redhat.com> writes:

> 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.

My point would be it is not strictly a regression either.  It is gdb not
handling new functionality.

If we can be backwards compatible and make ptrace_attach work that is
preferable.  If we can't saying the handful of ptrace using applications
need an upgrade to support processes that use io_uring may be
acceptable.

I don't see any easy to implement path that is guaranteed to work.

Eric




  parent reply	other threads:[~2021-03-25 20:50 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-25 16:43 [PATCH 0/2] Don't show PF_IO_WORKER in /proc/<pid>/task/ Jens Axboe
2021-03-25 16:43 ` [PATCH 1/2] kernel: don't include PF_IO_WORKERs as part of same_thread_group() Jens Axboe
2021-03-25 16:43 ` [PATCH 2/2] proc: don't show PF_IO_WORKER threads as threads in /proc/<pid>/task/ Jens Axboe
2021-03-29  1:57   ` [proc] 43b2a76b1a: will-it-scale.per_process_ops -11.3% regression kernel test robot
2021-03-25 19:33 ` [PATCH 0/2] Don't show PF_IO_WORKER in /proc/<pid>/task/ Eric W. Biederman
2021-03-25 19:38   ` Linus Torvalds
2021-03-25 19:40     ` Jens Axboe
2021-03-25 19:42     ` Linus Torvalds
2021-03-25 19:46       ` Jens Axboe
2021-03-25 20:21         ` Eric W. Biederman
2021-03-25 20:40           ` Oleg Nesterov
2021-03-25 20:43             ` Jens Axboe
2021-03-25 20:48             ` Eric W. Biederman [this message]
2021-03-25 20:42           ` Jens Axboe
2021-03-25 20:12       ` Linus Torvalds
2021-03-25 20:40         ` Jens Axboe
2021-03-25 21:44           ` Jens Axboe
2021-03-25 21:57             ` Stefan Metzmacher
2021-03-26  0:11               ` Jens Axboe
2021-03-26 11:59                 ` Stefan Metzmacher
2021-04-01 14:40                   ` Stefan Metzmacher
2021-03-25 22:37             ` Linus Torvalds
2021-03-26  0:08               ` Jens Axboe
2021-03-25 20:43         ` Eric W. Biederman
2021-03-25 21:50           ` Jens Axboe
2021-03-25 20:44         ` Oleg Nesterov
2021-03-25 20:55           ` Eric W. Biederman
2021-03-25 21:20             ` Stefan Metzmacher
2021-03-25 21:48               ` Stefan Metzmacher
2021-03-25 19:40   ` Jens Axboe
2021-03-25 20:32     ` Oleg Nesterov

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