ESXi 7.0 Host experiences a Purple Diagnostic Screen (PSOD) with #DF Exception 8 in Syscall_InstructionHandler

Products

• VMware vSphere ESXi

Issue/Introduction

An ESXi 7.0 host may fail with a Purple Diagnostic Screen (PSOD) showing a Double Fault (#DF) exception. The backtrace typically points to the system call handler.

• The PSOD screen displays: #DF Exception 8 IP 0x42000c34#### SP 0x453a89e4####
• The backtrace includes: Syscall_InstructionHandler@vmkernel#nover

Environment

VMware vSphere ESXi 7.0

Cause

This issue is caused by a race condition within the ESXi kernel's system call handler.

The failure occurs when a thread attempts to access a stack address that has already been unmapped. Specifically, a transition occurs where the kernel expects an active upcall stack, but that stack has already been torn down (unmapped). When the system attempts to handle this invalid stack reference, it triggers a Double Fault (#DF) because the exception handler itself cannot be properly invoked using the invalid stack pointer.

Resolution

Update the affected ESXi host to Build 22348816 or a newer cumulative update.

• Move the affected host into Maintenance Mode.
• Fix is available starting ESXi Patch 7.0 Update 3o
  It is recommended to patch the host using vSphere Lifecycle Manager (vLCM) to the latest supported 8.x
  https://knowledge.broadcom.com/external/article/390985/upgrading-updating-or-applying-a-patch-t.html