On Wed, 2023-04-19 at 16:21 +0300, Jani Nikula wrote: > 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; > > } > Thanks for the reviews! I finally had this happen again today, and I can confirm that this does prevent the oops. GNOME rearranged my screen layout after the error, but the box stayed up and running. -- Jeff Layton <jlayton@xxxxxxxxxx>
