As reported by Daniel Nashed and others, there have been issues with FP7 and some problems were only seen on Linux. IBM has released an IF1 to address the critical issues on Linux.
If you have installed FP7 on Linux and have not downgraded yet, I suggest you look into this alert.
Interim Fix 1 for Domino 9.0.1 Fix Pack 7 is now available for download from Fix Central. This Interim Fix is available for only Linux64 and zLinux64, and it addresses critical issues affecting those platforms. The issues stem from a threading mismatch and can surface in Domino as problems with cluster replication as well as potentially other critical issues. These issues are tracked as SPR KBRNAEMPX2.