macOS kernel return 23 (KERN_MEMORY_PRESENT): meaning and diagnosis

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: A memory manager tried to supply precious data for memory that is already present.

Could be also:
Constant	Type	OS
ERROR_CRC	Win32 error	Windows
ippStsDllNotFoundBestUsed	Intel Ipp Status	Any
ENFILE	errno	Any
CID_HANDLE_DELETION	BugCheck Code	Windows

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KERN_INVALID_HOST	KERN_MEMORY_DATA_MOVED

KERN_MEMORY_PRESENT

KERN_MEMORY_PRESENT is a specialized external-memory-management result. XNU defines it for an attempt to supply “precious” data for memory that is already present in a memory object. It is not a usual error from ordinary macOS application allocation APIs.

Mach virtual memory can be backed by memory objects whose contents are supplied and managed through pager-style interfaces. In that model, the kernel and memory manager coordinate which pages are present and which data may be supplied. Delivering data for a page that is already present conflicts with that state.

Why it matters

It usually indicates an inconsistency in a custom pager, kernel component, or other external-memory-management path.
It should be diagnosed from the memory object's state machine and page ownership, not by changing ordinary process heap settings.
Trace requests and replies for the relevant page range to find duplicate or late data supply.
Check the semantics of “precious” data in the memory-management implementation before retrying.

For end users this code is generally a symptom emitted by low-level software. For developers working at the Mach memory-object boundary, it identifies a specific contradiction: the manager attempted to provide data for a page already resident in the object.

References

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