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Date:      Fri, 30 Dec 2011 23:31:43 +0000
From:      "Robert N. M. Watson" <rwatson@FreeBSD.org>
To:        Maxim Sobolev <sobomax@FreeBSD.org>
Cc:        freebsd-net@freebsd.org, "Bjoern A. Zeeb" <bz@FreeBSD.ORG>, Jack Vogel <jfvogel@gmail.com>
Subject:   Re: Panic in the udp_input() under heavy load
Message-ID:  <AB3D0536-CDD7-4595-911C-7C17FE1DFB23@FreeBSD.org>
In-Reply-To: <4EFE158C.2040705@FreeBSD.org>
References:  <4EB804D2.2090101@FreeBSD.org> <alpine.BSF.2.00.1111071818250.4603@ai.fobar.qr> <4EB86276.6080801@sippysoft.com> <4EB86866.9060102@sippysoft.com> <alpine.BSF.2.00.1111072324340.4603@ai.fobar.qr> <4EB86FCF.3050306@FreeBSD.org> <alpine.BSF.2.00.1111080239500.1358@fledge.watson.org> <4ECEE6F0.4010301@FreeBSD.org> <F63603B1-7B35-4ECE-82E6-835CD91B93F8@FreeBSD.org> <4EFE158C.2040705@FreeBSD.org>

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On 30 Dec 2011, at 19:48, Maxim Sobolev wrote:

> On 11/24/2011 11:24 PM, Robert N. M. Watson wrote:
>>>> There was recently a commit to fix a race condition in 10-CURRENT =
which
>>>> >>  I think is not slated to be merged for 9.0. You might check the =
commit
>>>> >>  logs there and see if that fixes the problems you have -- if =
so, we
>>>> >>  might want to reconsider the plan not to merge for 9.0.
>>>> >>
>>>> >>  (It relates to a race condition on closing sockets..)
>>> >
>>> >  Thank you for the tip. I will give it a try and see what happens. =
So far, after installing that trap we have not seen any panics yet. I =
have not checked logs yet if my trap actually has catch anything or not.
>> Do we know if this fix has been merged to stable/9 and releng/9.0? =
Given multiple reports of instability without it, I think we would be =
well-served to merge it at this point.
>=20
> Hey Robert, sorry to bother you again, but can you at least point me =
towards specific SVN revisions that I need to get merged? I tried to =
google it and also browsed my svn history for the last 4 months using =
keyword "sockets", but nothing came up. This fix is critical for any =
system that does lot of fault-ctitical networking, and FreeBSD has =
always been solid in this regard. It saved us at least 10-15 crashes =
across 5 machines in the last month.

Hi Maxim:

Looking back at a recent post from you, it appears that you are on 8.x =
and not 9.x, as I had assumed form your original e-mail. The patch I was =
referring to in 9-CURRENT has long since been merged for 9.0 and will =
appear in that release. However, it does not apply to 8.x, as the bug it =
fixed was introduced during the 9.x cycle. We'll need to do a =
from-scratch diagnosis here rather than assume it's the same problem. =
Could I ask you to follow up to this post with version information, =
stack traces from relevant threads, etc? I am not aware of any other =
reports of UDP-related crashes along the lines of what you've described =
in 8.x, so it may be being triggered by some unusual aspect of your =
workload (or just bad luck). Sorry that there's no instant "merge a =
patch" fix for this one.

Thanks,

Robert=



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