linux-kernel - Re: [Regression] "iommu/amd: Relax locking in dma_ops path" makes tg3 ethernet transmit queue timeout

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Message-Id: <CFC22DE4-E342-4F32-B758-6A690755C498@canonical.com>
Date:   Mon, 29 Jun 2020 20:33:22 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Joerg Roedel <jroedel@...e.de>
Cc:     iommu@...ts.linux-foundation.org,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [Regression] "iommu/amd: Relax locking in dma_ops path" makes tg3
 ethernet transmit queue timeout


> On May 18, 2020, at 23:32, Kai-Heng Feng <kai.heng.feng@...onical.com> wrote:
> 
> 
> 
>> On May 18, 2020, at 22:05, Kai-Heng Feng <kai.heng.feng@...onical.com> wrote:
>> 
>> 
>> 
>>> On May 18, 2020, at 21:32, Joerg Roedel <jroedel@...e.de> wrote:
>>> 
>>> On Mon, May 18, 2020 at 05:06:45PM +0800, Kai-Heng Feng wrote:
>>>> Particularly, as soon as the spinlock is removed, the issue can be reproduced.
>>>> Function domain_flush_complete() doesn't seem to affect the status.
>>>> 
>>>> However, the .map_page callback was removed by be62dbf554c5
>>>> ("iommu/amd: Convert AMD iommu driver to the dma-iommu api"), so
>>>> there's no easy revert for this issue.
>>>> 
>>>> This is still reproducible as of today's mainline kernel, v5.7-rc6.
>>> 
>>> Is there any error message from the IOMMU driver?
>>> 
>> 
>> As of mainline kernel, there's no error message from IOMMU driver.
>> There are some complains from v4.15-rc1:
>> https://pastebin.ubuntu.com/p/qn4TXkFxsc/
> 
> Just tested v5.7-rc6, the issue disappears as soon as kernel boots with "iommu=off".

I am still seeing the issue on v5.8-rc3. The issue goes away as soon as "iommu=off" is added.

Kai-Heng

> 
> Kai-Heng
> 
>> 
>> Kai-Heng
>