Reported by 0day:

sparse: context imbalance in 'amdgpu_dm_commit_planes' - unexpected unlock

a0c37809 Harry Wentland 2017-08-10  3958                  spin_lock_irqsave(&crtc->dev->event_lock, flags); 
a0c37809 Harry Wentland 2017-08-10  3959                  if (acrtc_attach->pflip_status != AMDGPU_FLIP_NONE) { 
f56f75db Harry Wentland 2017-07-27  3960                          DRM_ERROR("%s: acrtc %d, already busy\n", 
f56f75db Harry Wentland 2017-07-27  3961                                    __func__, 
a0c37809 Harry Wentland 2017-08-10  3962                                    acrtc_attach->crtc_id); 
a0c37809 Harry Wentland 2017-08-10  3963                          spin_unlock_irqrestore(&crtc->dev->event_lock, flags); 
1224981c Harry Wentland 2017-07-26  3964                          /* In commit tail framework this cannot happen */ 
a0c37809 Harry Wentland 2017-08-10  3965                          WARN_ON(1); 
a0c37809 Harry Wentland 2017-08-10  3966                  } 
a0c37809 Harry Wentland 2017-08-10 @3967                  spin_unlock_irqrestore(&crtc->dev->event_lock, flags); 
a0c37809 Harry Wentland 2017-08-10  3968   

Indeed, the code shows a double unlock in the error case.