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    <body><span class="vcard"><a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> <span class="fn">Chris Wilson</span></a>
</span> changed
          <a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED FIXED - map_gtt reading/writing data mismatch during the GPU reset"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=99274">bug 99274</a>
          <br>
             <table border="1" cellspacing="0" cellpadding="8">
          <tr>
            <th>What</th>
            <th>Removed</th>
            <th>Added</th>
          </tr>

         <tr>
           <td style="text-align:right;">Resolution</td>
           <td>---
           </td>
           <td>FIXED
           </td>
         </tr>

         <tr>
           <td style="text-align:right;">Status</td>
           <td>NEEDINFO
           </td>
           <td>RESOLVED
           </td>
         </tr></table>
      <p>
        <div>
            <b><a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED FIXED - map_gtt reading/writing data mismatch during the GPU reset"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=99274#c4">Comment # 4</a>
              on <a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED FIXED - map_gtt reading/writing data mismatch during the GPU reset"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=99274">bug 99274</a>
              from <span class="vcard"><a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> <span class="fn">Chris Wilson</span></a>
</span></b>
        <pre>commit b1ed35d9179bc42c5ac7b86548cfae589be17b3e
Author: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>>
Date:   Wed Jan 4 14:51:10 2017 +0000

    drm/i915: Revoke fenced GTT mmapings across GPU reset

    The fence registers are clobbered by a GPU reset. If there is concurrent
    user access to a fenced region via a GTT mmaping, the access will not be
    fenced during the reset (until we restore the fences afterwards). In order
    to prevent invalid access during the reset, before we clobber the fences
    first we must invalidate the GTT mmapings. Access to the mmap will then
    be forced to fault in the page, and in handling the fault, i915_gem_fault()
    will take the struct_mutex and wait upon the reset to complete.

    v2: Fix up commentary.

    Bugzilla: <a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED FIXED - map_gtt reading/writing data mismatch during the GPU reset"
   href="show_bug.cgi?id=99274">https://bugs.freedesktop.org/show_bug.cgi?id=99274</a>
    Testcase: igt/gem_mmap_gtt/hang
    Signed-off-by: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>>
    Link:
<a href="http://patchwork.freedesktop.org/patch/msgid/20170104145110.1486-1-chris@chris-wilson.co.uk">http://patchwork.freedesktop.org/patch/msgid/20170104145110.1486-1-chris@chris-wilson.co.uk</a>
    Reviewed-by: Tvrtko Ursulin <<a href="mailto:tvrtko.ursulin@intel.com">tvrtko.ursulin@intel.com</a>></pre>
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