[solved] Kernel crash

Two times today on attempting to hibernate after exiting Xorg

Apr 26 14:40:19 hades kernel: Call Trace:
Apr 26 14:40:19 hades kernel: [] ? os_acquire_spinlock+0x12/0x20 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? nv_check_pci_config_space+0x1c9/0x300 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? _nv009868rm+0xe13/0x1a00 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? _nv009868rm+0x1783/0x1a00 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? _nv016600rm+0x134/0x6e0 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? _nv014811rm+0x58/0x70 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? _nv016600rm+0x134/0x6e0 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? nv_verify_pci_config+0x81/0x90 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? _nv016600rm+0x54d/0x6e0 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? _nv000746rm+0x59d/0x2940 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? _nv000710rm+0x1b09/0x1bc0 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? _nv016605rm+0x52/0x80 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? _nv000141rm+0x55/0x70 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? _nv000734rm+0x103/0x340 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? rm_disable_adapter+0x6a/0x130 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? nv_close_device+0xed/0x130 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? nvidia_dev_put+0x27/0x40 [nvidia]
Apr 26 14:40:19 hades kernel: [] ? nvkms_close_gpu+0x57/0x70 [nvidia_modeset]
Apr 26 14:40:19 hades kernel: [] ? _nv001953kms+0xf5/0x180 [nvidia_modeset]
Apr 26 14:40:19 hades kernel: [] ? _nv001859kms+0x3d/0x80 [nvidia_modeset]
Apr 26 14:40:19 hades kernel: [] ? _nv000189kms+0x53/0x130 [nvidia_modeset]
Apr 26 14:40:19 hades kernel: [] ? nvKmsClose+0x7c/0x120 [nvidia_modeset]
Apr 26 14:40:19 hades kernel: [] ? nvkms_close_common+0x21/0x60 [nvidia_modeset]
Apr 26 14:40:19 hades kernel: [] ? nvkms_close+0x1a/0x30 [nvidia_modeset]
Apr 26 14:40:19 hades kernel: [] ? nvidia_frontend_close+0x2c/0x50 [nvidia]
A

I figured out the cause. One X11 application was getting stuck and not quitting when Xorg exited. I fixed the application to exit correctly and the error no longer happens.