Re: [Dnsmasq-discuss] [BUG] RA are sent too fast and slows down the machine

[Simon Kelley]

On 21/08/2019 19:59, Petr Mensik wrote:
> Hi Simon and Maarten,
> 
> we discovered when playing with NetworkManager-ci [1], that lastest
> release is somehow broken. Test running dnsmasq are quite slow on latest
> release.
> 
> I have created repeatable started script that reproduces it. Then used
> git bisect to find when it was broken. It seems fast sending were
> intentional in commit 0a496f059c1e9 [2], but maybe way it affects the
> system were underestimated. It is significant for systems that hit such
> issue. I think it has to be fixed to slow it down to short time
> interval, not endless loop. Reported as Fedora bug [3].
> 
> 1. https://github.com/NetworkManager/NetworkManager-ci
> 2.
> http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=0a496f059c1e9d75c33cce4c1211d58422ba4f62
> 3. https://bugzilla.redhat.com/show_bug.cgi?id=1739797
> 

Petr,

returning to this after too long away, I've committed what seems like
the most sensible fix:


http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=515ba97595e60c762c448657f3c0e545c1e365f9

which is different from yours. It only starts fast-RA when the
dhcp-range in question has never been used before. This satisfies the
original aim of 0a496f059c1e9d75c33cce4c1211d58422ba4f62 but eliminates
the possibility of the infinite loop.

Does that work for you?


Simon.

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Re: [Dnsmasq-discuss] [BUG] RA are sent too fast and slows down the machine

[Petr Mensik]

Hi Vladislav,

No, I am talking about different issue, commit already released in
latest release. It was introduced by commit [1]. I have no proper fix
for it yet, but revert offending commit.

I think you were mentioning issue is have different reproducer for [2],
TCP no longer listened on interface after recreation. I have working fix
to that too [3], applied already in Fedora. Only feedback so far was
issue with [1], sounds good. Original issue with the same address is
already fixed. But my Thunderbird does not display it well, maybe others
have also issues with it. That is why I started creating pull requests
to myself...

1.
http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=0a496f059c1e9d75c33cce4c1211d58422ba4f62
2.
https://github.com/InfrastructureServices/dnsmasq-tests/blob/master/bz1728701.sh
3. https://github.com/InfrastructureServices/dnsmasq/pull/1

On 8/28/19 1:25 PM, Vladislav Grishenko wrote:
> Hi, Petr,
> 
> Just worrying, isn't this bug a side effect of previous interface-related 
> binding patch we're talking about?
> If yes, since it's not in upstream, it can be quite tricky to reproduce it on 
> vanilla sources.
> 
> Best Regards, Vladislav Grishenko
> 
> -Original Message-
> From: Dnsmasq-discuss  On 
> Behalf Of Petr Mensik
> Sent: Wednesday, August 28, 2019 12:11 PM
> To: dnsmasq-discuss@lists.thekelleys.org.uk
> Subject: Re: [Dnsmasq-discuss] [BUG] RA are sent too fast and slows down the 
> machine
> 
> Hi Iain,
> 
> of course. I am sorry, forgot to add a link as intended[1]. Used base report 
> from Network Manager tester report. I added it to Fedora bug mentioned, but 
> forgot to add script itself. At least to me, it produces tens of RA announces.
> 
> Regards,
> Petr
> 
> [1]
> https://github.com/InfrastructureServices/dnsmasq-tests/blob/master/bz1739797.sh
> 
> On 8/27/19 10:45 AM, Iain Lane wrote:
>> On Wed, Aug 21, 2019 at 08:59:07PM +0200, Petr Mensik wrote:
>>> Hi Simon and Maarten,
>>>
>>> we discovered when playing with NetworkManager-ci [1], that lastest 
>>> release is somehow broken. Test running dnsmasq are quite slow on 
>>> latest release.
>>>
>>> I have created repeatable started script that reproduces it. Then 
>>> used git bisect to find when it was broken. It seems fast sending 
>>> were intentional in commit 0a496f059c1e9 [2], but maybe way it 
>>> affects the system were underestimated. It is significant for systems 
>>> that hit such issue. I think it has to be fixed to slow it down to 
>>> short time interval, not endless loop. Reported as Fedora bug [3].
>>
>> Thanks for this Petr. Would you be able to share the script you've 
>> used, so that perhaps an upstream developer could recreate the bug?
>>
>> Mainly I wanted to chime in and say that (in addition to the other 
>> instance referenced), we found this in the NetworkManager testsuite in 
>> Ubuntu. I didn't come up with a nice reproducer at the time, but we 
>> did identify the same commit and we've reverted it in Ubuntu. I posted 
>> on the ML back then but we didn't get much traction and I didn't 
>> follow up very aggressively.
>>
>>   
>> http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2018q4/012709
>> .html
>>
>>   
>> https://launchpadlibrarian.net/405377161/dnsmasq_2.80-1_2.80-1ubuntu1.diff.gz
>>   (the commit ID referenced in the changelog there seems or from
>>   somewhere else, it's the same patch)
>>
>> Cheers,
>>

-- 
Petr Menšík
Software Engineer
Red Hat, http://www.redhat.com/
email: pemen...@redhat.com  PGP: 65C6C973

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Re: [Dnsmasq-discuss] [BUG] RA are sent too fast and slows down the machine

[Vladislav Grishenko]

Hi, Petr,

Just worrying, isn't this bug a side effect of previous interface-related 
binding patch we're talking about?
If yes, since it's not in upstream, it can be quite tricky to reproduce it on 
vanilla sources.

Best Regards, Vladislav Grishenko

-Original Message-
From: Dnsmasq-discuss  On 
Behalf Of Petr Mensik
Sent: Wednesday, August 28, 2019 12:11 PM
To: dnsmasq-discuss@lists.thekelleys.org.uk
Subject: Re: [Dnsmasq-discuss] [BUG] RA are sent too fast and slows down the 
machine

Hi Iain,

of course. I am sorry, forgot to add a link as intended[1]. Used base report 
from Network Manager tester report. I added it to Fedora bug mentioned, but 
forgot to add script itself. At least to me, it produces tens of RA announces.

Regards,
Petr

[1]
https://github.com/InfrastructureServices/dnsmasq-tests/blob/master/bz1739797.sh

On 8/27/19 10:45 AM, Iain Lane wrote:
> On Wed, Aug 21, 2019 at 08:59:07PM +0200, Petr Mensik wrote:
>> Hi Simon and Maarten,
>>
>> we discovered when playing with NetworkManager-ci [1], that lastest 
>> release is somehow broken. Test running dnsmasq are quite slow on 
>> latest release.
>>
>> I have created repeatable started script that reproduces it. Then 
>> used git bisect to find when it was broken. It seems fast sending 
>> were intentional in commit 0a496f059c1e9 [2], but maybe way it 
>> affects the system were underestimated. It is significant for systems 
>> that hit such issue. I think it has to be fixed to slow it down to 
>> short time interval, not endless loop. Reported as Fedora bug [3].
> 
> Thanks for this Petr. Would you be able to share the script you've 
> used, so that perhaps an upstream developer could recreate the bug?
> 
> Mainly I wanted to chime in and say that (in addition to the other 
> instance referenced), we found this in the NetworkManager testsuite in 
> Ubuntu. I didn't come up with a nice reproducer at the time, but we 
> did identify the same commit and we've reverted it in Ubuntu. I posted 
> on the ML back then but we didn't get much traction and I didn't 
> follow up very aggressively.
> 
>   
> http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2018q4/012709
> .html
> 
>   
> https://launchpadlibrarian.net/405377161/dnsmasq_2.80-1_2.80-1ubuntu1.diff.gz
>   (the commit ID referenced in the changelog there seems or from
>   somewhere else, it's the same patch)
> 
> Cheers,
> 
> 
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> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
> 

--
Petr Menšík
Software Engineer
Red Hat, http://www.redhat.com/
email: pemen...@redhat.com  PGP: 65C6C973



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Re: [Dnsmasq-discuss] [BUG] RA are sent too fast and slows down the machine

[Petr Mensik]

Hi Iain,

of course. I am sorry, forgot to add a link as intended[1]. Used base
report from Network Manager tester report. I added it to Fedora bug
mentioned, but forgot to add script itself. At least to me, it produces
tens of RA announces.

Regards,
Petr

[1]
https://github.com/InfrastructureServices/dnsmasq-tests/blob/master/bz1739797.sh

On 8/27/19 10:45 AM, Iain Lane wrote:
> On Wed, Aug 21, 2019 at 08:59:07PM +0200, Petr Mensik wrote:
>> Hi Simon and Maarten,
>>
>> we discovered when playing with NetworkManager-ci [1], that lastest
>> release is somehow broken. Test running dnsmasq are quite slow on latest
>> release.
>>
>> I have created repeatable started script that reproduces it. Then used
>> git bisect to find when it was broken. It seems fast sending were
>> intentional in commit 0a496f059c1e9 [2], but maybe way it affects the
>> system were underestimated. It is significant for systems that hit such
>> issue. I think it has to be fixed to slow it down to short time
>> interval, not endless loop. Reported as Fedora bug [3].
> 
> Thanks for this Petr. Would you be able to share the script you've used,
> so that perhaps an upstream developer could recreate the bug?
> 
> Mainly I wanted to chime in and say that (in addition to the other
> instance referenced), we found this in the NetworkManager testsuite in
> Ubuntu. I didn't come up with a nice reproducer at the time, but we did
> identify the same commit and we've reverted it in Ubuntu. I posted on
> the ML back then but we didn't get much traction and I didn't follow up
> very aggressively.
> 
>   http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2018q4/012709.html
> 
>   
> https://launchpadlibrarian.net/405377161/dnsmasq_2.80-1_2.80-1ubuntu1.diff.gz
>   (the commit ID referenced in the changelog there seems or from
>   somewhere else, it's the same patch)
> 
> Cheers,
> 
> 
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> 

-- 
Petr Menšík
Software Engineer
Red Hat, http://www.redhat.com/
email: pemen...@redhat.com  PGP: 65C6C973



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Re: [Dnsmasq-discuss] [BUG] RA are sent too fast and slows down the machine

[Maarten de Vries]

Hey,

I haven't dug very deep yet, but I can comment on the intent of the 
particular commit: without it, dnsmasq didn't do any unsolicited RAs on 
interfaces that are created after dnsmasq was started. It definitely 
should do unsolicited RAs on those interfaces too, although obviously 
not quite so many so often. I'm not sure why that happens. Note that the 
commit didn't introduce the fast RAs, it only enabled unsolicited RAs 
(including fast) for newly created interfaces too.


I wonder why this happens in those test cases and at-least one Raspberry 
Pi, but not on my server. Is there any information you could provide to 
pinpoint when exactly this bug triggers and when not? For example: what 
happens if the virtual interface is created before dnsmasq starts? Does 
it also trigger on bridge interfaces (which is what I personally tested 
the commit with) for you?


I will attempt to investigate too, but I'm somewhat swamped for time so 
I can't promise fast results.


Kinds regards,

Maarten


On 27-08-2019 10:45, Iain Lane wrote:

On Wed, Aug 21, 2019 at 08:59:07PM +0200, Petr Mensik wrote:

Hi Simon and Maarten,

we discovered when playing with NetworkManager-ci [1], that lastest
release is somehow broken. Test running dnsmasq are quite slow on latest
release.

I have created repeatable started script that reproduces it. Then used
git bisect to find when it was broken. It seems fast sending were
intentional in commit 0a496f059c1e9 [2], but maybe way it affects the
system were underestimated. It is significant for systems that hit such
issue. I think it has to be fixed to slow it down to short time
interval, not endless loop. Reported as Fedora bug [3].

Thanks for this Petr. Would you be able to share the script you've used,
so that perhaps an upstream developer could recreate the bug?

Mainly I wanted to chime in and say that (in addition to the other
instance referenced), we found this in the NetworkManager testsuite in
Ubuntu. I didn't come up with a nice reproducer at the time, but we did
identify the same commit and we've reverted it in Ubuntu. I posted on
the ML back then but we didn't get much traction and I didn't follow up
very aggressively.

   http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2018q4/012709.html

   https://launchpadlibrarian.net/405377161/dnsmasq_2.80-1_2.80-1ubuntu1.diff.gz
   (the commit ID referenced in the changelog there seems or from
   somewhere else, it's the same patch)

Cheers,


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Re: [Dnsmasq-discuss] [BUG] RA are sent too fast and slows down the machine

[Iain Lane]

On Wed, Aug 21, 2019 at 08:59:07PM +0200, Petr Mensik wrote:
> Hi Simon and Maarten,
> 
> we discovered when playing with NetworkManager-ci [1], that lastest
> release is somehow broken. Test running dnsmasq are quite slow on latest
> release.
> 
> I have created repeatable started script that reproduces it. Then used
> git bisect to find when it was broken. It seems fast sending were
> intentional in commit 0a496f059c1e9 [2], but maybe way it affects the
> system were underestimated. It is significant for systems that hit such
> issue. I think it has to be fixed to slow it down to short time
> interval, not endless loop. Reported as Fedora bug [3].

Thanks for this Petr. Would you be able to share the script you've used,
so that perhaps an upstream developer could recreate the bug?

Mainly I wanted to chime in and say that (in addition to the other
instance referenced), we found this in the NetworkManager testsuite in
Ubuntu. I didn't come up with a nice reproducer at the time, but we did
identify the same commit and we've reverted it in Ubuntu. I posted on
the ML back then but we didn't get much traction and I didn't follow up
very aggressively.

  http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2018q4/012709.html

  https://launchpadlibrarian.net/405377161/dnsmasq_2.80-1_2.80-1ubuntu1.diff.gz
  (the commit ID referenced in the changelog there seems or from
  somewhere else, it's the same patch)

Cheers,

-- 
Iain Lane  [ i...@orangesquash.org.uk ]
Debian Developer   [ la...@debian.org ]
Ubuntu Developer   [ la...@ubuntu.com ]


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Re: [Dnsmasq-discuss] [BUG] RA are sent too fast and slows down the machine

[Cooper Lees]

This sounds exactly like the bug I am seeing on my Raspberry Pi.

Discussion was here: 
http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2019q3/013200.html 

- Happy to test patches if you'd like

Cooper

> On Aug 21, 2019, at 11:59 AM, Petr Mensik  wrote:
> 
> Hi Simon and Maarten,
> 
> we discovered when playing with NetworkManager-ci [1], that lastest
> release is somehow broken. Test running dnsmasq are quite slow on latest
> release.
> 
> I have created repeatable started script that reproduces it. Then used
> git bisect to find when it was broken. It seems fast sending were
> intentional in commit 0a496f059c1e9 [2], but maybe way it affects the
> system were underestimated. It is significant for systems that hit such
> issue. I think it has to be fixed to slow it down to short time
> interval, not endless loop. Reported as Fedora bug [3].
> 
> 1. https://github.com/NetworkManager/NetworkManager-ci
> 2.
> http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=0a496f059c1e9d75c33cce4c1211d58422ba4f62
> 3. https://bugzilla.redhat.com/show_bug.cgi?id=1739797
> 
> -- 
> Petr Menšík
> Software Engineer
> Red Hat, http://www.redhat.com/
> email: pemen...@redhat.com  PGP: 65C6C973
> 
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