On Mon, 20 Jun 2011, Mandeep Singh Baines wrote: > Hi Dave, > > I think this change is causing a regression I'm seeing in panic. > Before this change, I'd get a > reboot on panic (we've configured as such). > > With this change, my machine gets wedged if the machine is running in > X when the panic occurs. > > I traced the code flow to this: > > bust_spinlocks(0); > ->unblank_screen(); > ->do_unblank_screen(0); > ->vc->vc_sw->con_blank(vc, 0, 0); > ->fbcon_blank(vc, 0, 0); > ->update_screen(vc); > ->redraw_screen(vc, 0); > ->vc->vc_sw->con_switch(vc); > ->fbcon_switch(vc); > ->ops->update_start(info); > ->bit_update_start(info); > ->fb_pan_display(info, &ops->var); > ->info->fbops->fb_pan_display(var, info); > ->drm_fb_helper_pan_display(var, info); > ->mutex_lock(&dev->mode_config.mutex); *this blocks* > > With this change, there is now a lot going on in the panic path. Stuff > that I'm not sure is safe when panicking. In addition to the > mutex_lock, there is also a del_timer_sync() > now happening in the context of panic(). > > I see this bug with a 2.6.38 kernel but did a quick scan of a newer > kernels and did not see anything that changed in this path so I > suspect its still there. > > Reverting this change fixes the regression. > Chris Fowler reports something similar when running 2.6.38 by inducing a kernel panic via the oom killer -- see http://marc.info/?l=linux-kernel&m=130805985022791. I've added him to the cc so he can participate in the thread and cherry-pick any fixes (last status update was that he was going to be trying 2.6.38.8). ------------------------------------------------------------------------------ EditLive Enterprise is the world's most technically advanced content authoring tool. Experience the power of Track Changes, Inline Image Editing and ensure content is compliant with Accessibility Checking. http://p.sf.net/sfu/ephox-dev2dev -- _______________________________________________ Dri-devel mailing list Dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
