On Thu, May 06, 2021 at 02:36:21PM +0200, Mark Kettenis wrote: > > Date: Thu, 6 May 2021 21:59:12 +1000 > > From: Jonathan Gray <j...@jsg.id.au> > > > > On Wed, May 05, 2021 at 04:47:50PM -0500, Scott Cheloha wrote: > > > > > > [...] > > > > > > On a hunch I added additional parameter checks to task_add(9) and > > > task_del(9) and caught intel(4) doing something strange. > > > > > > [...] > > > > > > And here is the panic on my machine. I had to reconstruct it from > > > OCR, the machine has no serial port, sorry if there are typos. > > > > boot crash can be helpful for such machines
Oh nice, thanks. > > > [...] > > > > > > db_enter() at db_enter+Oxa > > > panic(ffffffff81db24fb) at panic+0x12f > > > task del(0,ffff8000010633e0) at task_del+Oxa8 > > > edp_panel vdd_on(ffff800001063128) at edp_panel_vdd_on+0x6a > > > intel_dp_aux_xfer(ffff800001063128, ffffffff82512a20,4, > > > ffffffff82512400,2,0) at intel_dp_aux_xfer+0x18b > > > intel_dp_aux_transfer(ffff8000010631e8, ffffffff82512a88) at > > > intel_dp_aux_transfer+0x183 > > > drm_dp_dpcd_access(ffff8000010631e8,9,0,ffff80000106313a, 1) at > > > drm_dp_dpcd_access+Oxa9 > > > drm_dp_dpcd_read(ffff8000010631e8,0,ffff80000106313a, f) at > > > drm_dp_dpcd_read+0x61 > > > intel_dp_read_dpcd(ffff800001063128) at intel_dp_read_dpcd+0x45 > > > intel_dp_init_connector(ffff800001063000, ffff800001064000) at > > > intel_dp_init_connector+0x988 > > > intel_ddi_init(ffff800000272000,0) at intel_ddi_init+0x454 > > > intel_modeset_init(ffff800000272000) at intel_modeset_init+0x1c9f > > > i915_driver_probe(ffff800000272000, ffffffff82052f98) at > > > i915_driver_probe+0x7df > > > inteldrm_attachhook(ffff800000272000) at inteldrm_attachhook+0x46 > > > end trace frame: Oxffffffff82512700, count: 0 > > > > > > From the backtrace, I gather the following: > > > > > > edp_panel_vdd_on() calls clear_delayed_work() which is just a macro > > > > cancel_delayed_work() whoops > > > that calls task_del(). And for whatever reason the taskq passed to > > > task_del() is NULL. Maybe there is a missing INIT_DELAYED_WORK() call > > > somewhere prior to this point? > > > > the call to that is in > > INIT_DELAYED_WORK(&intel_dp->panel_vdd_work, edp_panel_vdd_work); > > but tq doesn't get set until work is scheduled as there are interfaces > > to pick a tq when scheduling work. > > > > So perhaps you want something like this to catch the cases where work is > > cancelled before it is scheduled. > > Yeah, I think that makes sense. > > ok kettenis@ This patch fixes the panic, running with it now. ok cheloha@ Caveat: my confidence in my understanding of these interfaces is pretty low. -Scott
