From: Pavel Begunkov <[email protected]>
To: Jens Axboe <[email protected]>, Daurnimator <[email protected]>
Cc: [email protected]
Subject: Re: [PATCHSET 0/4] Add support for shared io-wq backends
Date: Tue, 28 Jan 2020 00:45:22 +0300 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
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On 27/01/2020 23:33, Jens Axboe wrote:
> On 1/27/20 7:07 AM, Pavel Begunkov wrote:
>> On 1/27/2020 4:39 PM, Jens Axboe wrote:
>>> On 1/27/20 6:29 AM, Pavel Begunkov wrote:
>>>> On 1/26/2020 8:00 PM, Jens Axboe wrote:
>>>>> On 1/26/20 8:11 AM, Pavel Begunkov wrote:
>>>>>> On 1/26/2020 4:51 AM, Daurnimator wrote:
>>>>>>> On Fri, 24 Jan 2020 at 10:16, Jens Axboe <[email protected]> wrote:
>>>> Ok. I can't promise it'll play handy for sharing. Though, you'll be out
>>>> of space in struct io_uring_params soon anyway.
>>>
>>> I'm going to keep what we have for now, as I'm really not imagining a
>>> lot more sharing - what else would we share? So let's not over-design
>>> anything.
>>>
>> Fair enough. I prefer a ptr to an extendable struct, that will take the
>> last u64, when needed.
>>
>> However, it's still better to share through file descriptors. It's just
>> not secure enough the way it's now.
>
> Is the file descriptor value really a good choice? We just had some
> confusion on ring sharing across forks. Not sure using an fd value
> is a sane "key" to use across processes.
>
As I see it, the problem with @mm is that uring is dead-bound to it. For
example, a process can create and send uring (e.g. via socket), and then be
killed. And that basically means
1. @mm of the process is locked just because of the sent uring instance.
2. a process may have an io_uring, which bound to @mm of another process, even
though the layouts may be completely different.
File descriptors are different here, because io_uring doesn't know about them,
They are controlled by the userspace (send, dup, fork, etc), and don't sabotage
all isolation work done in the kernel. A dire example here is stealing io-wq
from within a container, which is trivial with global self-made id. I would love
to hear, if I am mistaken somewhere.
Is there some better option?
--
Pavel Begunkov
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next prev parent reply other threads:[~2020-01-27 21:46 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-23 23:16 [PATCHSET 0/4] Add support for shared io-wq backends Jens Axboe
2020-01-23 23:16 ` [PATCH 1/4] io-wq: make the io_wq ref counted Jens Axboe
2020-01-23 23:16 ` [PATCH 2/4] io-wq: add 'id' to io_wq Jens Axboe
2020-01-23 23:16 ` [PATCH 3/4] io-wq: allow lookup of existing io_wq with given id Jens Axboe
2020-01-24 9:54 ` Stefan Metzmacher
2020-01-24 16:41 ` Jens Axboe
2020-01-23 23:16 ` [PATCH 4/4] io_uring: add support for sharing kernel io-wq workqueue Jens Axboe
2020-01-24 9:51 ` [PATCHSET 0/4] Add support for shared io-wq backends Stefan Metzmacher
2020-01-24 16:43 ` Jens Axboe
2020-01-24 19:14 ` Stefan Metzmacher
2020-01-24 21:37 ` Jens Axboe
2020-01-24 20:34 ` Pavel Begunkov
2020-01-24 21:38 ` Jens Axboe
2020-01-26 1:51 ` Daurnimator
2020-01-26 15:11 ` Pavel Begunkov
2020-01-26 17:00 ` Jens Axboe
2020-01-27 13:29 ` Pavel Begunkov
2020-01-27 13:39 ` Jens Axboe
2020-01-27 14:07 ` Pavel Begunkov
2020-01-27 19:39 ` Pavel Begunkov
2020-01-27 19:45 ` Jens Axboe
2020-01-27 20:33 ` Jens Axboe
2020-01-27 21:45 ` Pavel Begunkov [this message]
2020-01-27 22:40 ` Jens Axboe
2020-01-27 23:00 ` Jens Axboe
2020-01-27 23:17 ` Pavel Begunkov
2020-01-27 23:23 ` Jens Axboe
2020-01-27 23:25 ` Pavel Begunkov
2020-01-27 23:38 ` Jens Axboe
2020-01-28 10:01 ` Stefan Metzmacher
2020-01-28 10:30 ` Pavel Begunkov
2020-01-28 10:35 ` Stefan Metzmacher
2020-01-28 10:51 ` Pavel Begunkov
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