Local denial of service via BPF mmap deadlock

Denial of service in the Linux kernel BPF map mmap path allows local users to deadlock affected systems through concurrent map operations. The mmap path holds map->freeze_mutex throughout memory-management and VMA manipulation instead of only during writable-permission checks, allowing a lock-order deadlock. Reaching the flaw requires local access and permission to perform BPF map and mapping operations; successful triggering hangs the affected kernel without disclosing or changing data.