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

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Message-ID: <CAHk-=wgUcVeaKhtBgJO3TfE69miJq-krtL8r_Wf_=LBTJw6WSg@mail.gmail.com>
Date:   Thu, 25 Mar 2021 13:12:42 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Jens Axboe <axboe@...nel.dk>, 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/

On Thu, Mar 25, 2021 at 12:42 PM Linus Torvalds
<torvalds@...ux-foundation.org> 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..

Actually, maybe the right model is to simply make all the io threads
take signals, and get rid of all the special cases.

Sure, the signals will never be delivered to user space, but if we

 - just made the thread loop do "get_signal()" when there are pending signals

 - allowed ptrace_attach on them

they'd look pretty much like regular threads that just never do the
user-space part of signal handling.

The whole "signals are very special for IO threads" thing has caused
so many problems, that maybe the solution is simply to _not_ make them
special?

           Linus