From: [email protected] (Eric W. Biederman)
To: Linus Torvalds <[email protected]>
Cc: Jens Axboe <[email protected]>, io-uring <[email protected]>,
Linux Kernel Mailing List <[email protected]>,
Oleg Nesterov <[email protected]>,
Stefan Metzmacher <[email protected]>
Subject: Re: [PATCH 0/2] Don't show PF_IO_WORKER in /proc/<pid>/task/
Date: Thu, 25 Mar 2021 15:43:34 -0500 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAHk-=wgUcVeaKhtBgJO3TfE69miJq-krtL8r_Wf_=LBTJw6WSg@mail.gmail.com> (Linus Torvalds's message of "Thu, 25 Mar 2021 13:12:42 -0700")
Linus Torvalds <[email protected]> writes:
> On Thu, Mar 25, 2021 at 12:42 PM Linus Torvalds
> <[email protected]> wrote:
>>
>> On Thu, Mar 25, 2021 at 12:38 PM Linus Torvalds
>> <[email protected]> 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?
The special case in check_kill_permission is certainly unnecessary.
Having the signal blocked is enough to prevent signal_pending() from
being true.
The most straight forward thing I can see is to allow ptrace_attach and
to modify ptrace_check_attach to always return -ESRCH for io workers
unless ignore_state is set causing none of the other ptrace operations
to work.
That is what a long running in-kernel thread would do today so
user-space aka gdb may actually cope with it.
We might be able to support if io workers start supporting SIGSTOP but I
am not at all certain.
Eric
next prev parent reply other threads:[~2021-03-25 20:45 UTC|newest]
Thread overview: 30+ 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
2021-03-25 19:33 ` [PATCH 0/2] Don't show PF_IO_WORKER " 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
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 [this message]
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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