Quoting Tvrtko Ursulin (2017-06-23 13:35:24) > > On 22/06/2017 11:56, Chris Wilson wrote: > > Trying to do a modeset from within a reset is fraught with danger. We > > can fall into a cyclic deadlock where the modeset is waiting on a > > previous modeset that is waiting on a request, and since the GPU hung > > that request completion is waiting on the reset. As modesetting doesn't > > allow its locks to be broken and restarted, or for its *own* reset > > mechanism to take over the display, we have to do something very > > evil instead. If we detect that we are stuck waiting to prepare the > > display reset (by using a very simple timeout), resort to cancelling all > > in-flight requests and throwing the user data into /dev/null, which is > > marginally better than the driver locking up and keeping that data to > > itself. > > > > This is not a fix; this is just a workaround that unbreaks machines > > until we can resolve the deadlock in a way that doesn't lose data! > > > > v2: Move the retirement from set-wegded to the i915_reset() error path, > > after which we no longer any delayed worker cleanup for > > i915_handle_error() > > v3: C abuse for syntactic sugar > > v4: Cover all waits with the timeout to catch more driver breakage > > > > References: https://bugs.freedesktop.org/show_bug.cgi?id=99093 > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> > > Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx> > > Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > [snip] > Looks OK - lets see how temporary it will end up being. :) I've grown to like the idea of having a watchdog here. We critically depend on reset to ensure forward progress of requests, and this gives us that extra layer of paranoid protection. > Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> Thanks, the real magic is still to come :) -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
