linux-kernel - Re: [PATCH 0/2] Don't show PF_IO

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Message-ID: <m1zgyr2ddh.fsf@fess.ebiederm.org>
Date:   Thu, 25 Mar 2021 15:21:30 -0500
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     Jens Axboe <axboe@...nel.dk>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        io-uring <io-uring@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Oleg Nesterov <oleg@...hat.com>,
        Stefan Metzmacher <metze@...ba.org>
Subject: Re: [PATCH 0/2] Don't show PF_IO_WORKER in /proc/<pid>/task/

Jens Axboe <axboe@...nel.dk> writes:

> On 3/25/21 1:42 PM, Linus Torvalds wrote:
>> On Thu, Mar 25, 2021 at 12:38 PM Linus Torvalds
>> <torvalds@...ux-foundation.org> wrote:
>>>
>>> I don't know what the gdb logic is, but maybe there's some other
>>> option that makes gdb not react to them?
>> 
>> .. maybe we could have a different name for them under the task/
>> subdirectory, for example (not  just the pid)? Although that probably
>> messes up 'ps' too..
>
> Heh, I can try, but my guess is that it would mess up _something_, if
> not ps/top.

Hmm.

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.

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.

Eric