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To:     Lu Baolu <baolu.lu@linux.intel.com>,
        Joerg Roedel <joro@8bytes.org>, Tom Murphy <murphyt7@tcd.ie>,
        David Woodhouse <dwmw2@infradead.org>,
        Christoph Hellwig <hch@infradead.org>
Cc:     Ashok Raj <ashok.raj@intel.com>, Intel-gfx@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org
References: <20200912032200.11489-1-baolu.lu@linux.intel.com>
 <776771a2-247a-d1be-d882-bee02d919ae0@deltatee.com>
 <fe94760f-3c10-4222-ec87-291c01325fef@linux.intel.com>
 <e95a55ea-b03f-4b3c-327a-b48d364577e9@deltatee.com>
 <c8bde158-50f6-1656-4a7d-6323573ba501@linux.intel.com>
From:   Logan Gunthorpe <logang@deltatee.com>
Message-ID: <0047a398-3246-9363-5092-adeab6a8b2b9@deltatee.com>
Date:   Tue, 22 Sep 2020 09:38:37 -0600
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Subject: Re: [Intel-gfx] [PATCH v3 0/6] Convert the intel iommu driver to the
 dma-iommu api
Precedence: bulk


On 2020-09-21 6:24 p.m., Lu Baolu wrote:
>>>> I'm trying to test this on an old Sandy Bridge, but found that I get
>>>> spammed with warnings on boot. I've put a sample of a few of them below.
>>>> They all seem to be related to ioat.
>>>>
>>>> I had the same issue with Tom's v2 but never saw this on his v1.
>>>
>>> Have you verified whether this could be reproduced with the lasted
>>> upstream kernel (without this patch series)?
>>
>> Yes.
> 
> I am sorry. Just want to make sure I understand you correctly. :-) When
> you say "yes", do you mean you could reproduce this with pure upstream
> kernel (5.9-rc6)?

I mean I've verified the bug does *not* exist without this patch set.

> 
>> Also, it's hitting a warning in the dma-iommu code which would not
>> be hit without this patch set.
> 
> Without this series, DMA APIs don't go through dma-iommu. Do you mind
> posting the warning message?

It was on my original email but here it is again:


[   44.057877] ------------[ cut here ]------------
[   44.063167] WARNING: CPU: 4 PID: 84 at drivers/iommu/dma-iommu.c:496
__iommu_dma_unmap+0x115/0x130
[   44.073351] Modules linked in:
[   44.076882] CPU: 4 PID: 84 Comm: kworker/4:1 Tainted: G        W
   5.9.0-rc4-00006-g110da1e703a2 #216
[   44.087935] Hardware name: Supermicro SYS-7047GR-TRF/X9DRG-QF, BIOS
3.0a 12/05/2013
[   44.096650] Workqueue: events work_for_cpu_fn
[   44.101644] RIP: 0010:__iommu_dma_unmap+0x115/0x130
[   44.107225] Code: 48 8b 0c 24 48 c7 44 24 10 00 00 00 00 48 c7 44 24
18 00 00 00 00 48 c7 44 24 20 00 00 00 00 48 c7 44 24 08 ff ff ff ff eb
8d <0f> 0b e9 74 ff ff ff e8 1f 36 66 00 66 66 2e 0f 1f 84 00 00 00 00
[   44.128443] RSP: 0000:ffffc90002397c38 EFLAGS: 00010206
[   44.134413] RAX: 0000000000200000 RBX: 0000000000080000 RCX:
0000000000000000
[   44.144487] RDX: 0000000000000403 RSI: ffffffff82a7fb20 RDI:
ffff888477804f30
[   44.152613] RBP: 00000000fec00000 R08: 00000000000fec00 R09:
00000000000fedff
[   44.160733] R10: 0000000000000002 R11: 0000000000000004 R12:
ffff888270c39000
[   44.168861] R13: ffff888472d85ee8 R14: 0000000000080000 R15:
0000000000000000
[   44.176980] FS:  0000000000000000(0000) GS:ffff888479800000(0000)
knlGS:0000000000000000
[   44.186198] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   44.192761] CR2: 0000000000000000 CR3: 0000000002a20001 CR4:
00000000000606e0
[   44.200871] Call Trace:
[   44.203716]  ? lockdep_hardirqs_on_prepare+0xad/0x180
[   44.209509]  iommu_dma_free+0x18/0x30
[   44.213734]  ioat_free_chan_resources+0x19e/0x300
[   44.219133]  ioat_dma_self_test+0x2a0/0x3d0
[   44.223964]  ioat_pci_probe+0x60e/0x903
[   44.228387]  local_pci_probe+0x42/0x80
[   44.232721]  work_for_cpu_fn+0x16/0x20
[   44.237037]  process_one_work+0x292/0x630
[   44.241644]  ? __schedule+0x344/0x970
[   44.245868]  worker_thread+0x227/0x3e0
[   44.250185]  ? process_one_work+0x630/0x630
[   44.254989]  kthread+0x136/0x150
[   44.258718]  ? kthread_use_mm+0x100/0x100
[   44.263334]  ret_from_fork+0x22/0x30
[   44.267474] irq event stamp: 1881262
[   44.271602] hardirqs last  enabled at (1881272): [<ffffffff811b8465>]
console_unlock+0x435/0x570
[   44.281593] hardirqs last disabled at (1881281): [<ffffffff811b845b>]
console_unlock+0x42b/0x570
[   44.291588] softirqs last  enabled at (1747140): [<ffffffff817da3e5>]
ioat_cleanup+0x65/0x470
[   44.301285] softirqs last disabled at (1747144): [<ffffffff817d797a>]
ioat_free_chan_resources+0x6a/0x300
[   44.312153] ---[ end trace ed0f88fd959a5a39 ]---