On Thu, 2023-04-13 at 15:31 +0300, Jani Nikula wrote: > On Thu, 13 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. > > > > The real bug is probably in the caller of this function, which is > > passing it a NULL state pointer, but this patch at least keeps my > > machine from oopsing when this occurs. > > My fear is that papering over this makes the root cause harder to find. > > Cc: Harry, Alex > > > BR, > Jani. > > I'm happy to help track down the root cause. Display drivers are somewhat outside my wheelhouse though. Maybe we can throw a WARNING when this happens? I'd just like it to not crash my machine. > > > > Link: https://bugzilla.redhat.com/show_bug.cgi?id=2184855 > > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > > --- > > drivers/gpu/drm/display/drm_dp_mst_topology.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c > > index 38dab76ae69e..87ad406c50f9 100644 > > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c > > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c > > @@ -3404,7 +3404,8 @@ 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(state ? state->dev : NULL, > > + "Part 1 of payload creation for %s failed, skipping part 2\n", > > payload->port->connector->name); > > return -EIO; > > } > -- Jeff Layton <jlayton@xxxxxxxxxx>
