From: Sasha Levin <sasha.levin@oracle.com>
To: Dmitry Vyukov <dvyukov@google.com>,
levinsasha928@gmail.com, Pekka Enberg <penberg@kernel.org>,
asias.hejun@gmail.com, penberg@cs.helsinki.fi,
gorcunov@gmail.com, Will Deacon <will.deacon@arm.com>,
andre.przywara@arm.com, matt@ozlabs.org, michael@ellerman.id.au,
prasadjoshi124@gmail.com, marc.zyngier@arm.com,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
mingo@elte.hu, gorcunov@openvz.org
Cc: kvm@vger.kernel.org, Kostya Serebryany <kcc@google.com>,
Evgenii Stepanov <eugenis@google.com>,
Alexey Samsonov <samsonov@google.com>,
Alexander Potapenko <glider@google.com>,
syzkaller@googlegroups.com
Subject: Re: Network hangs when communicating with host
Date: Fri, 16 Oct 2015 13:25:56 -0400 [thread overview]
Message-ID: <56213324.3010901@oracle.com> (raw)
In-Reply-To: <CACT4Y+b3kHo0f5VEEZdvRVNL_G0R3yXkXxF7uwCdc_VS7jbhMw@mail.gmail.com>
On 10/15/2015 04:20 PM, Dmitry Vyukov wrote:
> Hello,
>
> I am trying to run a program in lkvm sandbox so that it communicates
> with a program on host. I run lkvm as:
>
> ./lkvm sandbox --disk sandbox-test --mem=2048 --cpus=4 --kernel
> /arch/x86/boot/bzImage --network mode=user -- /my_prog
>
> /my_prog then connects to a program on host over a tcp socket.
> I see that host receives some data, sends some data back, but then
> my_prog hangs on network read.
>
> To localize this I wrote 2 programs (attached). ping is run on host
> and pong is run from lkvm sandbox. They successfully establish tcp
> connection, but after some iterations both hang on read.
>
> Networking code in Go runtime is there for more than 3 years, widely
> used in production and does not have any known bugs. However, it uses
> epoll edge-triggered readiness notifications that known to be tricky.
> Is it possible that lkvm contains some networking bug? Can it be
> related to the data races in lkvm I reported earlier today?
>
> I am on commit 3695adeb227813d96d9c41850703fb53a23845eb.
Hey Dmitry,
How long does it take to reproduce? I've been running ping/pong as you've
described and it looks like it doesn't get stuck (read/writes keep going
on both sides).
Can you share your guest kernel config maybe?
Thanks,
Sasha
next prev parent reply other threads:[~2015-10-16 17:28 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-15 20:20 Network hangs when communicating with host Dmitry Vyukov
2015-10-16 17:25 ` Sasha Levin [this message]
[not found] ` <CACT4Y+bG3gZv7eBUg5hv=5CEasdGUHwYEe6Bae6OVMK3bZe1Rw@mail.gmail.com>
2015-10-19 9:22 ` Andre Przywara
2015-10-19 9:28 ` Dmitry Vyukov
2015-10-19 14:20 ` Sasha Levin
2015-10-20 13:42 ` Dmitry Vyukov
2015-10-20 13:58 ` Sasha Levin
2015-10-27 9:31 ` Will Deacon
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