CVE-2025-68329

In the Linux kernel, the following vulnerability has been resolved:

tracing: Fix WARNON in tracingbuffersmmapclose for split VMAs

When a VMA is split (e.g., by partial munmap or MAPFIXED), the kernel calls vmops->close on each portion. For trace buffer mappings, this results in ringbufferunmap() being called multiple times while ringbuffermap() was only called once.

This causes ringbufferunmap() to return -ENODEV on subsequent calls because usermapped is already 0, triggering a WARNON.

Trace buffer mappings cannot support partial mappings because the ring buffer structure requires the complete buffer including the meta page.

Fix this by adding a may_split callback that returns -EINVAL to prevent VMA splits entirely.