<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 - Tonga VM Faults since llvm ScheduleDAGInstrs: Rework schedule graph builder."
   href="https://bugs.freedesktop.org/show_bug.cgi?id=93264">93264</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Tonga VM Faults since llvm ScheduleDAGInstrs: Rework schedule graph builder.
          </td>
        </tr>

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

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

        <tr>
          <th>Hardware</th>
          <td>x86-64 (AMD64)
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux (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/AMDgpu
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>dri-devel@lists.freedesktop.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>adf.lists@gmail.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>R9285 using Unreal ElementalDemo to trigger this.

It doesn't start till well into the demo at the same place that triggered an
older resolved issue.

<a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED FIXED - Tonga Elemental segfault + VM faults since radeon: implement r600_query_hw_get_result via function pointers"
   href="show_bug.cgi?id=93015">https://bugs.freedesktop.org/show_bug.cgi?id=93015</a>
(so maybe Nicolai knows what happens at this point in demo)

bisecting llvm came up with

c0a189c3792865257c1383f176e5401373ed2270 is the first bad commit
commit c0a189c3792865257c1383f176e5401373ed2270
Author: Matthias Braun <<a href="mailto:matze@braunis.de">matze@braunis.de</a>>
Date:   Thu Dec 3 02:05:27 2015 +0000

    ScheduleDAGInstrs: Rework schedule graph builder.

    The new algorithm remembers the uses encountered while walking backwards
    until a matching def is found. Contrary to the previous version this:
    - Works without LiveIntervals being available
    - Allows to increase the precision to subregisters/lanemasks
      (not used for now)

    The changes in the AMDGPU tests are necessary because the R600 scheduler
    is not stable with respect to the order of nodes in the ready queues.

    Differential Revision: <a href="http://reviews.llvm.org/D9068">http://reviews.llvm.org/D9068</a>


The demo continues to run/render OK, but I get thousands of -

amdgpu 0000:01:00.0: GPU fault detected: 147 0x07d04401
amdgpu 0000:01:00.0:   VM_CONTEXT1_PROTECTION_FAULT_ADDR   0x092D80FA
amdgpu 0000:01:00.0:   VM_CONTEXT1_PROTECTION_FAULT_STATUS 0x0A044001
VM fault (0x01, vmid 5) at page 153977082, read from 'TC7' (0x54433700) (68)
amdgpu 0000:01:00.0: GPU fault detected: 147 0x07d00401
amdgpu 0000:01:00.0:   VM_CONTEXT1_PROTECTION_FAULT_ADDR   0x0022D16B
amdgpu 0000:01:00.0:   VM_CONTEXT1_PROTECTION_FAULT_STATUS 0x0A0C4002
VM fault (0x02, vmid 5) at page 2281835, read from 'TC4' (0x54433400) (196)
amdgpu 0000:01:00.0: GPU fault detected: 147 0x07d04001
amdgpu 0000:01:00.0:   VM_CONTEXT1_PROTECTION_FAULT_ADDR   0x0022D163</pre>
        </div>
      </p>
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