CVE-2026-72174fs/proc/task_mmu: fix hugetlb self-deadlock in pagemap_scan_pte_hole()

In the Linux kernel, the following vulnerability has been resolved: fs/proc/task_mmu: fix hugetlb self-deadlock in pagemap_scan_pte_hole() A PAGEMAP_SCAN ioctl requesting PM_SCAN_WP_MATCHING on a hugetlb VMA hangs the calling thread, unkillably, as soon as the scan reaches an unpopulated part of the range: do_pagemap_scan() walk_page_range() walk_hugetlb_range() hugetlb_vma_lock_read() # take the vma lock for read ... pagemap_scan_pte_hole() # ... ->pte_hole() for a hole uffd_wp_range() change_protection() hugetlb_change_protection() hugetlb_vma_lock_write() # ... and block taking it for write walk_hugetlb_range() holds the hugetlb vma lock for read across the whole walk. A present entry goes to ->hugetlb_entry(); an unpopulated one goes to ->pte_hole(), i.e. pagemap_scan_pte_hole(). To write-protect the hole that handler calls uffd_wp_range(), which on a hugetlb VMA reaches hugetlb_change_protection() and takes the same vma lock for write. The thread then blocks in down_write() waiting for the read lock it is itself holding. The populated path avoids this: pagemap_scan_hugetlb_entry() write-protects the entry inline under the page-table lock and never enters hugetlb_change_protection(). Do the same for holes. Fault in the page table and install the uffd-wp marker directly with make_uffd_wp_huge_pte() under the page-table lock, rather than routing through uffd_wp_range(). That is the same sequence hugetlb_change_protection() runs for an unpopulated entry, minus the vma write lock -- which is safe to skip because PMD sharing is disabled on uffd-wp VMAs (hugetlb_unshare_all_pmds() runs at registration), leaving nothing for that lock to serialise against.

CVSS

Not yet scored

Weakness (CWE)

Not given

Known exploited

Not in CISA's KEV catalog

EPSS (exploitation in the next 30 days)

Not loaded for this CVE

Assigned by

Linux

NVD analysis

Received

Record last updated

Aug 17, 2026

First seen by InfoSec Signals

Oct 9, 2026

The CVE record on cve.org · NVD's entry

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