[$] A look at what's possible with BPF arenas

BPF arenas are areas of memory where the verifier can safely relax its checking ofpointers, allowing programmers to write arbitrary data structures in BPF. EmilTsalapatis reported on how his team has used arenas in writingsched_ext schedulers at the 2025 Linux Storage, Filesystem,Memory-Management, and BPF Summit. His biggest complaint was about the fact thatkernel pointers can't be stored in BPF arenas - something that the BPFdevelopers hope to address, although there are some implementation problems thatmust be sorted out first.