Well, now I found where the -2 comes from. intel_dp_register_mst_connector() calls drm_connector_register(), which fails to add the kobject (warning below). But, it does zero error checking on the drm_connector_register() call and leaves the partially-constructed connector in place. The next time some poor, hapless code goes and tries to do anything with that kdev, they oops. I'm perplexed by this, though. The drm_dp_mst_topology_cbs->register_connector just returns void. It seems a bit goofy that it can't even _return_ failure. Is there some stable code to go back to here? Or, is there something about my configuration that's unique? I really wonder why nobody else is running into this. There's probably some other race going on here. This warning doesn't happen on every boot. > [ 1.396475] ------------[ cut here ]------------ > [ 1.396486] WARNING: CPU: 0 PID: 91 at lib/kobject.c:244 kobject_add_internal+0x108/0x2d0 > [ 1.396492] kobject_add_internal failed for card0-DP-3 (error: -2 parent: card0) > [ 1.396496] Modules linked in: > [ 1.396500] CPU: 0 PID: 91 Comm: kworker/0:2 Not tainted 4.10.0-rc2-dirty #58 > [ 1.396503] Hardware name: LENOVO 20F5S7V800/20F5S7V800, BIOS R02ET50W (1.23 ) 09/20/2016 > [ 1.396509] Workqueue: events_long drm_dp_mst_link_probe_work > [ 1.396511] Call Trace: > [ 1.396517] dump_stack+0x67/0x99 > [ 1.396521] __warn+0xd1/0xf0 > [ 1.396524] warn_slowpath_fmt+0x4f/0x60 > [ 1.396527] kobject_add_internal+0x108/0x2d0 > [ 1.396531] ? vsnprintf+0x112/0x4b0 > [ 1.396533] kobject_add+0x65/0xb0 > [ 1.396537] ? klist_init+0x31/0x40 > [ 1.396542] device_add+0x102/0x5d0 > [ 1.396546] ? kfree_const+0x22/0x30 > [ 1.396549] device_create_groups_vargs+0xd8/0x100 > [ 1.396553] device_create_with_groups+0x36/0x40 > [ 1.396557] ? drm_fb_helper_add_one_connector+0x57/0xd0 > [ 1.396561] ? kmem_cache_alloc_trace+0x1d2/0x1f0 > [ 1.396566] drm_sysfs_connector_add+0x60/0xe0 > [ 1.396570] drm_connector_register+0x21/0xc0 > [ 1.396575] intel_dp_register_mst_connector+0x41/0x50 > [ 1.396579] drm_dp_add_port+0x350/0x450 > [ 1.396583] ? rcu_early_boot_tests+0x1/0x10 > [ 1.396587] ? schedule_timeout+0x1cd/0x390 > [ 1.396591] ? __might_sleep+0x4a/0x90 > [ 1.396594] ? mutex_lock+0x25/0x50 > [ 1.396597] ? drm_dp_mst_wait_tx_reply+0x118/0x1e0 > [ 1.396600] ? prepare_to_wait_event+0x120/0x120 > [ 1.396603] ? drm_dp_check_mstb_guid+0x3d/0x120 > [ 1.396606] drm_sysfs_connector_add() connector: ffff88040ed3f000 kdev: ffff88040c55dc00 > [ 1.396610] drm_dp_send_link_address+0x185/0x1f0 > [ 1.396614] drm_dp_check_and_send_link_address+0xad/0xc0 > [ 1.396617] drm_dp_mst_link_probe_work+0x57/0xa0 > [ 1.396620] process_one_work+0x14b/0x430 > [ 1.396623] worker_thread+0x12b/0x4a0 > [ 1.396626] kthread+0x10c/0x140 > [ 1.396629] ? process_one_work+0x430/0x430 > [ 1.396632] ? kthread_create_on_node+0x40/0x40 > [ 1.396635] ret_from_fork+0x27/0x40 > [ 1.396639] ---[ end trace dd05bb2cd9ebd900 ]--- > [ 1.396643] drm_sysfs_connector_add() connector: ffff88040c75a000 kdev: fffffffffffffffe > [ 1.396648] [drm:drm_sysfs_connector_add] *ERROR* failed to register connector device: -2 > [ 1.396651] drm_connector_register(ffff88040ed3f000) connector->registered: 1 > [ 1.396666] drm_sysfs_connector_add() connector: ffff88040ed3f800 kdev: ffff88040c55e400 > [ 1.396700] drm_connector_register(ffff88040ed3f800) connector->registered: 1 > [ 1.396717] drm_sysfs_connector_add() connector: ffff88040ed39800 kdev: ffff88040c55e800 > [ 1.396726] drm_connector_register(ffff88040ed39800) connector->registered: 1 > [ 1.396743] drm_sysfs_connector_add() connector: ffff88040c758000 kdev: ffff88040c55ec00 > [ 1.396769] drm_connector_register(ffff88040c758000) connector->registered: 1 > [ 1.396786] drm_sysfs_connector_add() connector: ffff88040c758800 kdev: ffff88040c55f000 > [ 1.396799] drm_connector_register(ffff88040c758800) connector->registered: 1 > [ 1.396804] drm_connector_register(ffff88040c75a000) connector->registered: 1 > [ 1.398665] ACPI: Video Device [GFX0] (multi-head: yes rom: no post: no) > [ 1.398893] drm_sysfs_connector_add() connector: ffff88040c75b000 kdev: ffff88040c790400 > [ 1.398907] drm_connector_register(ffff88040c75b000) connector->registered: 1 > [ 1.398930] drm_sysfs_connector_add() connector: ffff88040c75c000 kdev: ffff88040c790800 > [ 1.398939] drm_connector_register(ffff88040c75c000) connector->registered: 1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
