Mac Pro dual CPU sleep panic, shortened relevant excerpt

panic(cpu 0): pmLock: waited too long, held by 8

Panicked task: kernel_task

Relevant backtrace:
com.apple.driver.AppleIntelCPUPowerManagement:
_i386_pmExitHaltToOff

mach_kernel:
_acpi_sleep_kernel

com.apple.driver.AppleACPIPlatform:
AppleACPIPlatformExpert::sleepPlatform
AppleACPICPU::haltCPU

mach_kernel:
IOCPUSleepKernel
IOPMrootDomain::powerChangeDone

Kernel Extensions in backtrace:
com.apple.driver.AppleACPIPlatform 6.1
com.apple.driver.AppleIntelCPUPowerManagement 222.0

Boot args during failure:
keepsyms=1 debug=0x100 -lilubetaall -btlfxallowanyaddr ipc_control_port_options=0 -nokcmismatchpanic cpus=12

macOS:
15.7.7
Build 24G720

Kernel:
Darwin 24.6.0
x86_64

System model:
MacPro5,1

pmset result:
Failure during sleep: 0x00000019
Failure while halting non-boot CPUs panic

The same panic occurred repeatedly with cpus=12.
The stable workaround is cpus=8.