On Wed, 19 Apr 2023, Jeff Layton <jlayton@xxxxxxxxxx> wrote: > I've been experiencing some intermittent crashes down in the display > driver code. The symptoms are ususally a line like this in dmesg: > > amdgpu 0000:30:00.0: [drm] Failed to create MST payload for port 000000006d3a3885: -5 > > ...followed by an Oops due to a NULL pointer dereference. > > Switch to using mgr->dev instead of state->dev since "state" can be > NULL in some cases. > > Link: https://bugzilla.redhat.com/show_bug.cgi?id=2184855 > Suggested-by: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> Thanks, Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx> > --- > drivers/gpu/drm/display/drm_dp_mst_topology.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > I've been running this patch for a couple of days, but the problem > hasn't occurred again as of yet. It seems sane though as long as we can > assume that mgr->dev will be valid even when "state" is a NULL pointer. > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c > index 38dab76ae69e..e2e21ce79510 100644 > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c > @@ -3404,7 +3404,7 @@ int drm_dp_add_payload_part2(struct drm_dp_mst_topology_mgr *mgr, > > /* Skip failed payloads */ > if (payload->vc_start_slot == -1) { > - drm_dbg_kms(state->dev, "Part 1 of payload creation for %s failed, skipping part 2\n", > + drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s failed, skipping part 2\n", > payload->port->connector->name); > return -EIO; > } -- Jani Nikula, Intel Open Source Graphics Center
