Recently I've been unable to exit X-Plane because by doing so my entire system will freeze. No Ctrl+Alt+F1, no Ctrl+Alt+Del, nothing solves it. The worse part is that my X-Plane's Log.txt has no information of the problem as the last lines are always "shutting down". I suspect of three main causes: either Firejail's problem; grsecurity's problem; or X-Plane's problem. Or all together. Things to consider about Firejail: Firejail was my first suspicion (although not likely) because it has had a history or problems related to pulseaudio, in which applications would crash because of pulseaudio. This isn't a Firejail bug, but a pulseaudio bug. However, I already applied the fix, and X-Plane is the only program with problems. Things to consider about GRSecurity: I haven't had any problems with grsec and programs in the past. I always disable the "MPROTEC" Kernel protection that stops programs from injecting new executable code into the memory. This protection only works at START, when programs are opened, and NOT when they exit. However, even after disabling all kernel protections for X-Plane (PEMRS), the Sim still crashes my system at exit. However (2), there are these interesting lines at journalctl: Code: Dec 24 15:36:26 amarildo kernel: RIP [<ffffffff8b0b1238>] mutex_optimistic_spin+0x48/0x1c0 Dec 24 15:36:26 amarildo kernel: RSP <ffffc90007cab820> Dec 24 15:36:26 amarildo kernel: ---[ end trace ff9d409d9db085d8 ]--- Dec 24 15:36:26 amarildo kernel: grsec: banning user with uid 1000 until system restart for suspicious kernel crash Dec 24 15:36:26 amarildo kernel: Fixing recursive fault but reboot is needed! -- Reboot -- This could indicate that GRSecurity is picking illegal activities comming from X-Plane. Another thing to consider is that this could be a grsecurity problem, although not likely. I can't be 100% sure about this, but this problem started to happen after this recent GRSec Kernel. The older one, which I don't remember the number but is easy to track down, worked OK. However, why would only X-Plane have problems with it? Also, I'm not sure X-Plane is compatible with Kernel 4.3.3. Things to consider about X-Plane: I also noticed my firewall picking up UDP traffic trying to come in while I played X-Plane. This traffic is DENIED, only selected ports are allowed to function. Here's the journalctl lines (there are hundreds of these): Code: 15:35:38 amarildo kernel: RULE 21 -- DENY IN= OUT=enp0s7 SRC=187.XXX.XXX.XX DST=184.108.40.206 LEN=58 TOS=0x00 PREC=0x00 TTL=1 ID=48105 Here is the Firewall line that says "after the allowed traffic, all other attempts are denied": Code: # ALL UDP iptables -N RULE_21 iptables -A OUTPUT -p udp -m udp -j RULE_21 iptables -A INPUT -p udp -m udp -j RULE_21 iptables -A RULE_21 -j LOG --log-level info --log-prefix "RULE 21 -- DENY " iptables -A RULE_21 -j DROP -------------------------------------------------------------------------------------- My Setup: - Arch Linux, fully up-to-date; - X-Plane running from Steam, all files verified to be intact; - Radeon drivers. Using "--force_run" command. These drivers have better performance than proprietary Catalyst; - AMD R9 270X; - Kernel: Linux amarildo 220.127.116.11512222129-1-grsec #1 SMP PREEMPT Wed Dec 23 02:03:09 EST 2015 x86_64 GNU/Linux; - MATE Desktop Environment; - KDE 5 is installed too, though I rarely use it; Mesa: Code: [root@amarildo ~]# pacman -Qs mesa local/glu 9.0.0-4 Mesa OpenGL Utility library local/lib32-glu 9.0.0-3 Mesa OpenGL utility library (32 bits) local/lib32-libtxc_dxtn 1.0.1-5 S3 Texture Compression (S3TC) library for Mesa (32-bit) local/lib32-mesa 11.1.0-1 an open-source implementation of the OpenGL specification (32-bit) local/lib32-mesa-libgl 11.1.0-1 Mesa 3-D graphics library (32-bit) local/lib32-mesa-vdpau 11.1.0-1 Mesa VDPAU drivers (32-bit) local/libtxc_dxtn 1.0.1-6 S3 Texture Compression (S3TC) library for Mesa local/mesa 11.1.0-1 an open-source implementation of the OpenGL specification local/mesa-libgl 11.1.0-1 Mesa 3-D graphics library local/mesa-vdpau 11.1.0-1 Mesa VDPAU drivers [root@amarildo ~]# I'm copying a few things ATM, but at the end I'll make my system crash again. Then, I'll post the Log.txt so you guys can look at it. The last thing to consider: This is my second system install since the problem. After re-installing the system once, I tried to reproduce the problem: Having multiple firejail sandboxes opened, grsec in place with only the MPROTEC disabled for X-Plane, etc. Didn't happen, the Sim ran fine. Somewhere, after re-installing the system again, something must have caused this to happen, either a program or a configuration, I don't know. I'll re-install everything again and try to see where the problem is. This will take several hours so I appreciate your help in the mean time. Cheers.