Hi Hans, Fedora has a (opt-in) system to automatically collect backtraces from software crashing on users systems. This includes collecting kernel backtraces (including once triggered by WARN macros) while looking a the top 10 of the most reported backtrace during the last 2 weeks report from ABRT: https://retrace.fedoraproject.org/faf/problems/ I noticed the following backtrace: https://retrace.fedoraproject.org/faf/problems/8150/ which has been reported 170000 times by Fedora users who have opted-in during the last 14 days. The issue here is that cec_register_adapter ends up calling request_module() from an async context, triggering this warn in kernel/kmod.c __request_module(): /* * We don't allow synchronous module loading from async. Module * init may invoke async_synchronize_full() which will end up * waiting for this task which already is waiting for the module * loading to complete, leading to a deadlock. */ WARN_ON_ONCE(wait && current_is_async()); The call-path leading to this goes like this: ? kvasprintf+0x6d/0xa0 ? kobject_set_name_vargs+0x6f/0x90 rc_map_get+0x30/0x60 rc_register_device+0x108/0x510 cec_register_adapter+0x5c/0x280 [cec] drm_dp_cec_set_edid+0x11e/0x178 [drm_kms_helper] intel_dp_set_edid+0x8d/0xc0 [i915] intel_dp_detect+0x188/0x5c0 [i915] drm_helper_probe_single_connector_modes+0xc2/0x6d0 [drm_kms_helper] ? krealloc+0x7b/0xb0 drm_client_modeset_probe+0x25b/0x1320 [drm] ? kfree+0x1ea/0x200 ? sched_clock+0x5/0x10 ? sched_clock_cpu+0xc/0xa0 __drm_fb_helper_initial_config_and_unlock+0x37/0x470 [drm_kms_helper] ? _cond_resched+0x16/0x40 intel_fbdev_initial_config+0x14/0x30 [i915] async_run_entry_fn+0x39/0x160 So 2 questions: 1. Can we get this fixed please ? Related to this, what happens if we make this an async modprobe (when running from async context) is that a problem, or is it fine if the rc_map module gets loaded later ? 2. If the answer to 1. is "tricky", "maybe" or some such then can we look into a workaround here ? E.g. do we know in advance which module is going to be requested (1), or does that depend on the EDID data ? Regards, Hans 1) And can we thus do tricks with a softdep on it ? _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
