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From: Dmitry Kadashev <[email protected]>
To: Jens Axboe <[email protected]>
Cc: Josef <[email protected]>,
	io-uring <[email protected]>,
	Norman Maurer <[email protected]>
Subject: Re: "Cannot allocate memory" on ring creation (not RLIMIT_MEMLOCK)
Date: Mon, 21 Dec 2020 17:31:51 +0700	[thread overview]
Message-ID: <CAOKbgA7NAFcrELjX0A5aE9X7MHgSVeOZuvHywGB_oCHs=C-Hxw@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>

On Sun, Dec 20, 2020 at 12:11 AM Jens Axboe <[email protected]> wrote:
>
> On 12/19/20 9:29 AM, Jens Axboe wrote:
> > On 12/19/20 9:13 AM, Jens Axboe wrote:
> >> On 12/18/20 7:49 PM, Josef wrote:
> >>>> I'm happy to run _any_ reproducer, so please do let us know if you
> >>>> manage to find something that I can run with netty. As long as it
> >>>> includes instructions for exactly how to run it :-)
> >>>
> >>> cool :)  I just created a repo for that:
> >>> https://github.com/1Jo1/netty-io_uring-kernel-debugging.git
> >>>
> >>> - install jdk 1.8
> >>> - to run netty: ./mvnw compile exec:java
> >>> -Dexec.mainClass="uring.netty.example.EchoUringServer"
> >>> - to run the echo test: cargo run --release -- --address
> >>> "127.0.0.1:2022" --number 200 --duration 20 --length 300
> >>> (https://github.com/haraldh/rust_echo_bench.git)
> >>> - process kill -9
> >>>
> >>> async flag is enabled and these operation are used: OP_READ,
> >>> OP_WRITE, OP_POLL_ADD, OP_CLOSE, OP_ACCEPT
> >>>
> >>> (btw you can change the port in EchoUringServer.java)
> >>
> >> This is great! Not sure this is the same issue, but what I see here is
> >> that we have leftover workers when the test is killed. This means the
> >> rings aren't gone, and the memory isn't freed (and unaccounted), which
> >> would ultimately lead to problems of course, similar to just an
> >> accounting bug or race.
> >>
> >> The above _seems_ to be related to IOSQE_ASYNC. Trying to narrow it
> >> down...
> >
> > Further narrowed down, it seems to be related to IOSQE_ASYNC on the
> > read requests. I'm guessing there are cases where we end up not
> > canceling them on ring close, hence the ring stays active, etc.
> >
> > If I just add a hack to clear IOSQE_ASYNC on IORING_OP_READ, then
> > the test terminates fine on the kill -9.
>
> And even more so, it's IOSQE_ASYNC on the IORING_OP_READ on an eventfd
> file descriptor.

In our case - unlike netty - we use io_uring only for disk IO, no eventfd. And
we do not use IOSQE_ASYNC (we've tried, but this coincided with some kernel
crashes, so we've disabled it for now - not 100% sure if it's related or not
yet).

I'll try (again) to build a simpler reproducer for our issue, which is probably
different from the netty one.

-- 
Dmitry Kadashev

      parent reply	other threads:[~2020-12-21 10:33 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-17  8:19 "Cannot allocate memory" on ring creation (not RLIMIT_MEMLOCK) Dmitry Kadashev
2020-12-17  8:26 ` Norman Maurer
2020-12-17  8:36   ` Dmitry Kadashev
2020-12-17  8:40     ` Dmitry Kadashev
2020-12-17 10:38       ` Josef
2020-12-17 11:10         ` Dmitry Kadashev
2020-12-17 13:43           ` Victor Stewart
2020-12-18  9:20             ` Dmitry Kadashev
2020-12-18 17:22               ` Jens Axboe
2020-12-18 15:26 ` Jens Axboe
2020-12-18 17:21   ` Josef
2020-12-18 17:23     ` Jens Axboe
2020-12-19  2:49       ` Josef
2020-12-19 16:13         ` Jens Axboe
2020-12-19 16:29           ` Jens Axboe
2020-12-19 17:11             ` Jens Axboe
2020-12-19 17:34               ` Norman Maurer
2020-12-19 17:38                 ` Jens Axboe
2020-12-19 20:51                   ` Josef
2020-12-19 21:54                     ` Jens Axboe
2020-12-19 23:13                       ` Jens Axboe
2020-12-19 23:42                         ` Josef
2020-12-19 23:42                         ` Pavel Begunkov
2020-12-20  0:25                           ` Jens Axboe
2020-12-20  0:55                             ` Pavel Begunkov
2020-12-21 10:35                               ` Dmitry Kadashev
2020-12-21 10:49                                 ` Dmitry Kadashev
2020-12-21 11:00                                 ` Dmitry Kadashev
2020-12-21 15:36                                   ` Pavel Begunkov
2020-12-22  3:35                                   ` Pavel Begunkov
2020-12-22  4:07                                     ` Pavel Begunkov
2020-12-22 11:04                                       ` Dmitry Kadashev
2020-12-22 11:06                                         ` Dmitry Kadashev
2020-12-22 13:13                                           ` Dmitry Kadashev
2020-12-22 16:33                                         ` Pavel Begunkov
2020-12-23  8:39                                           ` Dmitry Kadashev
2020-12-23  9:38                                             ` Dmitry Kadashev
2020-12-23 11:48                                               ` Dmitry Kadashev
2020-12-23 12:27                                                 ` Pavel Begunkov
2020-12-20  1:57                             ` Pavel Begunkov
2020-12-20  7:13                               ` Josef
2020-12-20 13:00                                 ` Pavel Begunkov
2020-12-20 14:19                                   ` Pavel Begunkov
2020-12-20 15:56                                     ` Josef
2020-12-20 15:58                                       ` Pavel Begunkov
2020-12-20 16:14                                   ` Jens Axboe
2020-12-20 16:59                                     ` Josef
2020-12-20 18:23                                       ` Josef
2020-12-20 18:41                                         ` Pavel Begunkov
2020-12-21  8:22                                           ` Josef
2020-12-21 15:30                                             ` Pavel Begunkov
2020-12-21 10:31               ` Dmitry Kadashev [this message]

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