linux-kernel - Re: panic in dmar_remove_one_dev

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Message-ID: <20191217061325.fbzcxgh4sng5lkn7@cantor>
Date:   Mon, 16 Dec 2019 23:13:25 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     iommu@...ts.linux-foundation.org,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Subject: Re: panic in dmar_remove_one_dev_info

On Mon Dec 16 19, Jerry Snitselaar wrote:
>HP is seeing a panic on gen9 dl360 and dl560 while testing these other
>changes we've been eorking on. I just took an initial look, but have
>to run to a dentist appointment so couldn't dig too deep. It looks
>like the device sets dev->archdata.iommu to DEFER_DEVICE_DOMAIN_INFO
>in intel_iommu_add_device, and then it needs a private domain so
>dmar_remove_one_dev_info gets called. That code path ends up trying to
>use DEFER_DEVICE_DOMAIN_INFO as a pointer.  I don't need if there just
>needs to be a check in there to bail out if it sees
>DEFER_DEVICE_DOMAIN_INFO, or if something more is needed. I'll look
>at it some more when I get back home.
>
>Regards,
>Jerry

Hi Baolu,

Does this look sane?

--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -5163,7 +5163,8 @@ static void dmar_remove_one_dev_info(struct device *dev)
  
         spin_lock_irqsave(&device_domain_lock, flags);
         info = dev->archdata.iommu;
-       if (info)
+       if (info && info != DEFER_DEVICE_DOMAIN_INFO
+           && info != DUMMY_DEVICE_DOMAIN_INFO)
                 __dmar_remove_one_dev_info(info);
         spin_unlock_irqrestore(&device_domain_lock, flags);
  }




Regards,
Jerry