<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - [CI][BAT] igt@i915_selftest@live_hangcheck - incomplete - BUG: kernel NULL pointer dereference, address: 0000000000000028" href="https://bugs.freedesktop.org/show_bug.cgi?id=111905#c5">Comment # 5</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - [CI][BAT] igt@i915_selftest@live_hangcheck - incomplete - BUG: kernel NULL pointer dereference, address: 0000000000000028" href="https://bugs.freedesktop.org/show_bug.cgi?id=111905">bug 111905</a> from <a class="email" href="mailto:chris@chris-wilson.co.uk" title="Chris Wilson <chris@chris-wilson.co.uk>"> Chris Wilson</a> <pre>commit c949ae431467764277cdd88d7c26ff963a9db40a Author: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>> Date: Wed Oct 9 11:09:54 2019 +0100 drm/i915/execlists: Protect peeking at execlists->active Now that we dropped the engine->active.lock serialisation from around process_csb(), direct submission can run concurrently to the interrupt handler. As such execlists->active may be advanced as we dequeue, dropping the reference to the request. We need to employ our RCU request protection to ensure that the request is not freed too early. Fixes: df403069029d ("drm/i915/execlists: Lift process_csb() out of the irq-off spinlock") Signed-off-by: Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk">chris@chris-wilson.co.uk</a>> Cc: Mika Kuoppala <<a href="mailto:mika.kuoppala@linux.intel.com">mika.kuoppala@linux.intel.com</a>> Cc: Tvrtko Ursulin <<a href="mailto:tvrtko.ursulin@intel.com">tvrtko.ursulin@intel.com</a>> Reviewed-by: Tvrtko Ursulin <<a href="mailto:tvrtko.ursulin@intel.com">tvrtko.ursulin@intel.com</a>> Link: <a href="https://patchwork.freedesktop.org/patch/msgid/20191009100955.21477-1-chris@chris-wilson.co.uk">https://patchwork.freedesktop.org/patch/msgid/20191009100955.21477-1-chris@chris-wilson.co.uk</a> is a vaguely related patch. It shouldn't impact this path along reset, but maybe it provides a hint?</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> <li>You are on the CC list for the bug.</li> <li>You are the QA Contact for the bug.</li> </ul> </body> </html>