Deadlock in shared mem mutex when apps are killed

## Required information

**Operating system:**
Ubuntu 18.04 LTS

**Compiler version:**
GCC 7.4.0

**Observed result or behaviour:**
Deadlock in shared mem mutex when apps are killed

**Expected result or behaviour:**
No deadlock.

**Conditions where it occurred / Performed steps:**
Kill an app while some system is running

## Related issues
- #2193
- #2260