CVE-2026-93218

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

mm/huge_memory: skip device-private PMDs in madvise_free_huge_pmd

madvise_free_pte_range() checks pmd_trans_huge(*pmd) unlocked, then

madvise_free_huge_pmd() takes pmd_trans_huge_lock(). pmd_is_huge()

returns true for a device-private PMD, so orig_pmd can be device-private

and enter the !pmd_present() branch.

Skip device-private PMDs in that non-present branch and continue to out

before calling pmd_folio(). Downgrade the check to VM_WARN_ON_ONCE() so

an unexpected PMD softleaf logs a warning rather than panicking. Drop the

thp_migration_supported() guard: it expands to

IS_ENABLED(CONFIG_ARCH_SUPPORTS_PMD_SOFTLEAF), and both

pmd_is_migration_entry() and pmd_is_device_private_entry() already return

false when that config is not selected, so the guard suppresses only the

case where the warning would already be silent.

Potential trigger: an HMM-based GPU driver races with madvise(MADV_FREE):

migrate_vma_pages() flip

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References