Re: reproducable panic eviction work queue

On 07/20/2015 02:47 PM, Frank Schreuder wrote:

On 7/18/2015  05:32 PM, Nikolay Aleksandrov wrote:

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On 07/18/2015 05:28 PM, Johan Schuijt wrote:

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Thx for your looking into this!

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Thank you for the report, I will try to reproduce this locally
Could you please post the full crash log ?

Of course, please see attached file.

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Also could you test
with a clean current kernel from Linus' tree or Dave's -net ?

Will do.

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These are available at:
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
respectively.

One last question how many IRQs do you pin i.e. how many cores
do you actively use for receive ?

This varies a bit across our systems, but we’ve managed to reproduce this with IRQs pinned on as many as 2,4,8 or 20 cores.

I won’t have access to our test-setup till Monday again, so I’ll be testing 3 scenario’s then:
- Your patch

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- Linux tree
- Dave’s -net tree

Just one of these two would be enough. I couldn't reproduce it here but
I don't have as many machines to test right now and had to improvise with VMs. :-)

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I’ll make sure to keep you posted on all the results then. We have a kernel dump of the panic, so if you need me to extract any data from there just let me know! (Some instructions might be needed)

- Johan

Great, thank you!

I'm able to reproduce this panic on the following kernel builds:
- 3.18.7
- 3.18.18
- 3.18.18 + patch from Nikolay Aleksandrov
- 4.1.0

Would you happen to have any more suggestions we can try?

Thanks,
Frank

Unfortunately I was wrong about my theory because I mixed qp and qp_in, the new frag
doesn't make the chainlist if that codepath is hit so it couldn't mix the flags.
I'm still trying (unsuccessfully) to reproduce this, I've tried with up to 4 cores
and 4 different pinned irqs but no luck so far.
Anyway, I'll keep looking into this and will let you know if I get anywhere.