CVE-2026-80719

A flaw was found in the Linux kernel's Multi-Generational Least Recently Used (MGLRU) page table walker. When memory cgroup (memcg) reparenting occurs concurrently with page table walks, stale batch updates can lead to an underestimation of the number of pages. This can prevent the kernel from reclaiming memory effectively, potentially causing premature Out Of Memory (OOM) conditions and system instability.

A flaw of MODERATE impact was found in the Linux kernel's Multi-Generational LRU (MGLRU) page table walker. While walking page tables, the walker batches per-generation size deltas in walk->nr_pages without holding the lruvec lock; if the memory cgroup (memcg) owning that lruvec is offlined and its folios reparented to the parent memcg in the meantime, reset_batch_size() can later fold the pending deltas into the stale child lruvec. This leaves the MGLRU per-generation page accounting (lrugen->nr_pages) inconsistent and underestimates the number of pages present. Because MGLRU does not attempt to reclaim memory once nr_pages appears to have reached zero while more pages remain, the user-visible consequence is premature out-of-memory (OOM) conditions and system instability, that is, a local denial of service. Triggering the race requires local access with control over memory pressure and memory cgroup lifecycle conditions; there is no impact to confidentiality or integrity (CVSS:3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Red Hat Enterprise Linux 7, 8, 9, and 10 and Red Hat In-Vehicle OS 2 kernel and kernel-rt components are not affected because the vulnerable code is not present in these products; the Red Hat Enterprise Linux 6 Extended Lifecycle Support stream is out of support scope.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.