Mach trap#-63
svc · mach trap -63
mach_vm_reclaim_update_kernel_accounting_trap
Refresh the kernel's view of a process's VM reclaim ring buffer accounting.
Prototype
kern_return_t mach_vm_reclaim_update_kernel_accounting_trap(/* 3 args */);Returns: kern_return_t
Version history
| XNU tag | macOS | # |
|---|---|---|
| xnu-12377.1.9 | macOS 26.0 Tahoe | -63 |
| xnu-12377.101.15 | — | -63 |
| xnu-12377.41.6 | — | -63 |
| xnu-12377.61.12 | — | -63 |
| xnu-12377.81.4 | — | -63 |
Notes
Modern macOS exposes a userland-driven "VM reclaim" ring that lets a process voluntarily mark pages as discardable so the kernel can repossess them under memory pressure without the cost of full madvise traps. This trap notifies the kernel that the userland indices have moved so its bookkeeping (footprint, ledger entries) stays accurate. It is called by libmalloc's deferred-reclaim path, not by application code.
Detection
DTrace mach_trap provider; per-task reclaim activity also shows up in vm_stat and footprint(1) output.
Related APIs
madvisemach_vm_deallocatetask_infomalloc_zone_pressure_relief