The reported issue occurs in the Linux kernel’s memory management for x86 architectures, where an unnecessary copy of a page middle directory (PMD) page during free operations caused a circular locking dependency. The deadlock cycle involves the mmap_lock taken when changing page attributes, the pool_shrink_rwsem used during TTM page pool shrinkage, and a re-entrant acquisition of mmap_lock during ioremap. As a result, kswapd can become blocked, leading to stalled memory reclamation and system performance degradation. This does not provide direct data disclosure or arbitrary code execution, but the denial‑of‑service impact could be critical on production systems with discrete GPUs.

The vulnerability affects all Linux kernel versions that compile with the x86 memory management code described, specifically those including the TTM page pool handling and ioremap functions. The exact version range is not listed, but the patch is present in newer kernel releases such as 7.3.0-rc3 and later, and any kernel that has incorporated the commit added to prevent PMD copy during freeing.

The impact is a lock ordering bug that can lead to deadlock under normal kernel operation when the system performs memory reclamation. The CVSS score is not provided, and the EPSS score is unavailable, suggesting that the exploitability data is not currently published. The vulnerability is not listed in CISA’s KEV catalog. Inferred attack vector is internal, requiring normal kernel execution paths; an attacker on a compromised system can trigger the deadlock by inducing memory pressure, but no remote exploitation path is described.