<html>
    <head>
      <base href="https://bugs.freedesktop.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - igfx iommu causes hangs: DMAR: DRHD: handling fault status reg 3"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=111451">111451</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>igfx iommu causes hangs: DMAR: DRHD: handling fault status reg 3
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>DRI
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>DRI git
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Other
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>medium
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>DRM/Intel
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>intel-gfx-bugs@lists.freedesktop.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>pmenzel+bugs.freedesktop.org@molgen.mpg.de
          </td>
        </tr>

        <tr>
          <th>QA Contact</th>
          <td>intel-gfx-bugs@lists.freedesktop.org
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>intel-gfx-bugs@lists.freedesktop.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=145112" name="attach_145112" title="Linux kernel 5.2.9 messages">attachment 145112</a> <a href="attachment.cgi?id=145112&action=edit" title="Linux kernel 5.2.9 messages">[details]</a></span>
Linux kernel 5.2.9 messages

Debian enabled CONFIG_INTEL_IOMMU_DEFAULT_ON=y in Linux 5.2.9 [1], and now
there are hangs on the Dell Latitude E7250, often after using the laptops
function brightness keys.

```
[   41.975448] DMAR: DRHD: handling fault status reg 3
[   41.975456] DMAR: [DMA Write] Request device [00:02.0] fault addr
fffec1003000 [fault reason 23] Unknown
[   41.987006] DMAR: DRHD: handling fault status reg 3
[   41.987013] DMAR: [DMA Write] Request device [00:02.0] fault addr
fffec1006000 [fault reason 23] Unknown
[   42.157270] DMAR: DRHD: handling fault status reg 3
[   42.157275] DMAR: [DMA Write] Request device [00:02.0] fault addr
fffec1003000 [fault reason 23] Unknown
[   42.886618] DMAR: DRHD: handling fault status reg 3
[   47.549330] dmar_fault: 11 callbacks suppressed
[   47.549333] DMAR: DRHD: handling fault status reg 3
[   47.549343] DMAR: [DMA Write] Request device [00:02.0] fault addr
fffec1006000 [fault reason 23] Unknown
[   48.699784] DMAR: DRHD: handling fault status reg 3
[   48.699799] DMAR: [DMA Write] Request device [00:02.0] fault addr
fffec1003000 [fault reason 23] Unknown
[   48.880717] DMAR: DRHD: handling fault status reg 3
[   48.880733] DMAR: [DMA Write] Request device [00:02.0] fault addr
fffec1006000 [fault reason 23] Unknown
[   50.033196] DMAR: DRHD: handling fault status reg 3
[   57.985477] i915 0000:00:02.0: GPU HANG: ecode 8:1:0xfffffffe, in
gnome-shell [938], hang on rcs0
[   57.985479] [drm] GPU hangs can indicate a bug anywhere in the entire gfx
stack, including userspace.
[   57.985479] [drm] Please file a _new_ bug report on bugs.freedesktop.org
against DRI -> DRM/Intel
[   57.985479] [drm] drm/i915 developers can then reassign to the right
component if it's not a kernel issue.
[   57.985480] [drm] The gpu crash dump is required to analyze gpu hangs, so
please always attach it.
[   57.985480] [drm] GPU crash dump saved to /sys/class/drm/card0/error
[   57.986489] i915 0000:00:02.0: Resetting rcs0 for hang on rcs0
[…]
```

Booting with `intel_iommu=igfx_off` fixes this [2].

This seems to be a common problem [3][4][5][6].

[1]: <a href="https://bugs.debian.org/934309">https://bugs.debian.org/934309</a>
[2]: <a href="https://bugs.kali.org/view.php?id=5644">https://bugs.kali.org/view.php?id=5644</a>
[3]: <a href="https://bbs.archlinux.org/viewtopic.php?id=230362">https://bbs.archlinux.org/viewtopic.php?id=230362</a>
[4]: <a href="https://bugzilla.kernel.org/show_bug.cgi?id=202723">https://bugzilla.kernel.org/show_bug.cgi?id=202723</a>
[5]: <a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - iommu_intel=on + i915 incompatibility in 4.17, 4.19.13 and drm-tip"
   href="show_bug.cgi?id=109219">https://bugs.freedesktop.org/show_bug.cgi?id=109219</a>
[6]: <a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - [bdw-u iommu] DMAR error -> GPU hang"
   href="show_bug.cgi?id=89360">https://bugs.freedesktop.org/show_bug.cgi?id=89360</a>
[4]: <a class="bz_bug_link 
          bz_status_CLOSED  bz_closed"
   title="CLOSED WORKSFORME - [v4.13 ARCH] GPU HANG: DMAR: DRHD: handling fault status reg 3 (arch reverted the use of intel_iommu=igfx_off)"
   href="show_bug.cgi?id=103076">https://bugs.freedesktop.org/show_bug.cgi?id=103076</a></pre>
        </div>
      </p>


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