Memory Management Overhaul Proposed: 'Policy Groups' Aim to Fix Kernel Cgroup Limitations

Breaking: New 'Policy Groups' Framework Pitched at Linux Summit

At the 2026 Linux Storage, Filesystem, Memory Management, and BPF Summit, kernel developer Chris Li unveiled a controversial proposal to introduce policy groups into the memory management subsystem. The initiative directly targets well-known shortcomings in the current control group (cgroup) architecture.

Memory Management Overhaul Proposed: 'Policy Groups' Aim to Fix Kernel Cgroup Limitations

Li opened by acknowledging cgroups’ success for resource management but criticized their inflexibility for other memory policy use cases. "Control groups work well for resource management, but they're less effective for other use cases," Li told fellow developers. His proposed enhancement would allow memory policies to be set independently of process grouping hierarchies.

Background: The Cgroup Conundrum

Control groups have been a cornerstone of Linux resource management for years, dividing processes into hierarchical groups and limiting their CPU, memory, and I/O usage. However, memory management requires more nuanced policies—such as swap preferences, NUMA binding, and memory tiering—that cgroups struggle to express.

Li observed that real-world kernel deployments often need to apply different memory policies to processes within the same cgroup, or share a policy across processes in different cgroups. The existing framework forces users to either duplicate configurations or create complex nested hierarchies, which complicates system administration and reduces performance.

What Chris Li Proposed: Policy Groups in Detail

Policy groups would act as a separate abstraction layer between memory policies and process grouping. Each process could be assigned to one or more policy groups, each dictating specific memory behavior rules. For example, a database process might be in a policy group that prefers local memory, while a batch job in the same cgroup could use remote memory.

Li presented early prototypes that reuse existing kernel infrastructure for memory management while adding new policy group controls via cgroupfs-like files. "This is not a replacement for cgroups, but an extension that decouples policy from hierarchy," he emphasized during his session.

Lack of Consensus Sparking Debate

Despite the technical merits, a consensus among kernel maintainers remains elusive. Several attendees raised concerns about complexity, overlap with existing memory controller features, and potential performance overhead from multiple policy lookups.

David Howells, a veteran filesystem developer, questioned the need for a separate group mechanism: "We already have memory cgroups and memory tiers—adding yet another grouping layer could lead to confusion and data integrity issues." Li countered that current solutions require invasive changes to user-space tools, whereas policy groups could be adopted gradually.

What This Means for Linux and Containers

If adopted, policy groups could transform memory management in containerized environments. Currently, container runtimes like Docker or Kubernetes map each container to a single cgroup, forcing a one-size-fits-all memory policy. Policy groups would let system administrators fine-tune memory behavior per workload without restructuring container hierarchies.

For instance, a latency-sensitive web server could be given strict local memory affinity, while a cache-heavy background job could use slower memory tiers—all within the same container cgroup. This granularity could improve overall system memory efficiency by up to 15% in early benchmarks Li shared.

What This Means for Kernel Development Process

The proposal highlights a broader tension in the kernel community: balancing innovation with stability. Policy groups require changes to core memory management code that could affect performance tuning and debugging tools. Several attendees urged caution, suggesting the feature be prototyped as an out-of-tree module first.

Li, however, is optimistic. "We can’t keep patching cgroups for every new memory policy need. A clean abstraction will benefit everyone in the long run," he told Linux Weekly News after the session. The next step is a formal patch series for review on the linux-mm mailing list.

Urgent Timeline: When to Expect Decisions

With the Linux kernel merge window for version 6.15 approaching, developers are under pressure to either accept or reject the policy groups concept. Li hopes to have a minimal viable implementation ready for inclusion by late 2026. The summit’s memory-management track will reconvene in a few months to evaluate progress.

Quote Roundup

Chris Li (Proposer): "Control groups work well for resource management, but they're less effective for other use cases."
David Howells (Veteran Developer): "We already have memory cgroups and memory tiers—adding yet another grouping layer could lead to confusion."
Anonymous Summit Attendee: "This could be a game-changer for cloud providers, but only if it doesn't break existing setups."

Looking Ahead: Policy Groups vs. Alternative Approaches

Meanwhile, competing proposals exist to enhance cgroup memory controllers directly. Some developers advocate for extending the existing memory.limit_in_bytes and memory.pressure files rather than introducing a new subsystem. The debate is set to continue on the linux-kernel mailing list in the coming weeks.

For now, policy groups remain a concept—one that promises greater flexibility but demands careful integration. As Li summed up: "The kernel’s memory management must evolve. Policy groups are a step in that direction."

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