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BUG: Mellanox crash with iommu=soft and swiotlb=force

DISCUSSION Christoffer Dall 2 participants 4 messages Sep 28, 2015 – Oct 11, 2015

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#0 lore raw

Hi,

In doing some performance experiments I found that using a 10G Mellanox MX354A Dual port FDR CX3 device on a server running Apache and running ab against that server causes the system to crash with 'iommu=soft swiotlb=force'. The same behavior is seen without these options on Dom0 running under Xen.

I have tried this on v4.0 and v4.3-rc3.

Examples of crashes:
http://pastebin.ubuntu.com/11953498/
http://pastebin.ubuntu.com/11953443/

Kernel config (v4.3):
http://paste.ubuntu.com/12605446/

To reproduce, host a file in apache server on a system with the Mellanox NIC (I used the 41K index file of the GCC manual) and run ab (apache bench) from a client machine, something like this:

$ ab -n 100000 -c 100 http://10.10.1.2/gcc/index.html

I'm afraid debugging this is out of my area of expertise. Is this something you could have a look at?

Thanks,
-Christoffer

#1 lore raw
Quoted 9 lines · Christoffer Dall

Hi,

In doing some performance experiments I found that using a 10G Mellanox MX354A Dual port FDR CX3 device on a server running Apache and running ab against that server causes the system to crash with 'iommu=soft swiotlb=force'. The same behavior is seen without these options on Dom0 running under Xen.

I have tried this on v4.0 and v4.3-rc3.

Woops, needs looking indeed. Unfortunately many people in the team are off for the Sukkot holiday with real backing to business coming to play on Oct 6th -- not sure we can really respond on that before.

Are you running over ARM? which? if not, is that x86 64bit?

Or.

Quoted 23 lines

Examples of crashes:
http://pastebin.ubuntu.com/11953498/
http://pastebin.ubuntu.com/11953443/

Kernel config (v4.3):
http://paste.ubuntu.com/12605446/

To reproduce, host a file in apache server on a system with the Mellanox NIC (I used the 41K index file of the GCC manual) and run ab (apache bench) from a client machine, something like this:

$ ab -n 100000 -c 100 http://10.10.1.2/gcc/index.html

I'm afraid debugging this is out of my area of expertise. Is this something you could have a look at?

Thanks,
-Christoffer
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#2 lore raw
Quoted 10 lines · Or Gerlitz
Quoted 8 lines · Christoffer Dall

Hi,

In doing some performance experiments I found that using a 10G Mellanox MX354A Dual port FDR CX3 device on a server running Apache and running ab against that server causes the system to crash with 'iommu=soft swiotlb=force'. The same behavior is seen without these options on Dom0 running under Xen.

Quoted 8 lines
Quoted 1 line

I have tried this on v4.0 and v4.3-rc3.

Woops, needs looking indeed. Unfortunately many people in the team are off for the Sukkot holiday with real backing to business coming to play on Oct 6th -- not sure we can really respond on that before.

Are you running over ARM? which? if not, is that x86 64bit?

I'm running on x86_64.

Thanks,
-Christoffer

#3 lore raw
In reply to Or Gerlitz

Hi,

Quoted 10 lines · Or Gerlitz
Quoted 8 lines · Christoffer Dall

Hi,

In doing some performance experiments I found that using a 10G Mellanox MX354A Dual port FDR CX3 device on a server running Apache and running ab against that server causes the system to crash with 'iommu=soft swiotlb=force'. The same behavior is seen without these options on Dom0 running under Xen.

Quoted 6 lines
Quoted 1 line

I have tried this on v4.0 and v4.3-rc3.

Woops, needs looking indeed. Unfortunately many people in the team are off for the Sukkot holiday with real backing to business coming to play on Oct 6th -- not sure we can really respond on that before.

Friendly reminder on this one. Did anyone have a look?

Thanks,
-Christoffer