Linux 5.1 has not been released. Meanwhile, you can read about the features it will include here:
Summary: TBD
1. Coolest features
2. Core (various)
3. File systems
4. Memory management
Allow excluding balloon pages from kdump crash dumps to reduce their size. Also exclude them from hibernation image. commit commit commit commit commit commit commit commit
Various vmalloc() fixes and a new vmalloc test module and script. commit commit commit commit commit commit commit commit
On arm64, enables HugeTLB migration support for all supported huge page sizes at all levels including contiguous bit implementation. commit commit commit commit commit
Increase success rates and reduce latency of compaction (physical memory defragmentation), reducing the number of scanned pages for migration by 65%, and free pages for migration targets by 97%, while improving transparent hugepage allocation success rates significantly. commit commit commit commit commit commit commit commit commit commit commit commit commit commit commit commit commit commit commit commit commit commit
Prevent SLAB and other pages with special type to be mapped into userspace, for improved security. commit commit
Remove the OOM killer heuristic that preferred to kill children of the "worst" process rather than the process itself. commit
