{"api_version":"1","generated_at":"2026-07-20T14:42:06+00:00","cve":"CVE-2026-64181","urls":{"html":"https://cve.report/CVE-2026-64181","api":"https://cve.report/api/cve/CVE-2026-64181.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-64181","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-64181"},"summary":{"title":"mm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special()\n\nOn x86 32-bit with THP enabled, zap_huge_pmd() is seen to generate a\n\"WARNING: mm/memory.c:735 at __vm_normal_page+0x6a/0x7d\", from the\nVM_WARN_ON_ONCE(is_zero_pfn(pfn) || is_huge_zero_pfn(pfn)); followed by\n\"BUG: Bad rss-counter state\"s, then later \"BUG: Bad page state\"s when\nreclaim gets to call shrink_huge_zero_folio_scan().\n\nIt's as if the _PAGE_SPECIAL bit never got set in the huge_zero pmd: and\nindeed, whereas pte_special() and pte_mkspecial() are subject to a\ndedicated CONFIG_ARCH_HAS_PTE_SPECIAL, pmd_special() and pmd_mkspecial()\nare subject to CONFIG_ARCH_SUPPORTS_PMD_PFNMAP, which is never enabled on\nany 32-bit architecture.\n\nWhile the problem was exposed through commit d80a9cb1a64a\n(\"mm/huge_memory: add and use normal_or_softleaf_folio_pmd()\"), it was an\noversight in commit af38538801c6 (\"mm/memory: factor out common code from\nvm_normal_page_*()\") and would result in other problems:\n* huge zero folio accounted in smaps, pagemap (PAGE_IS_FILE) and\n  numamaps as file-backed THP\n* folio_walk_start() returning the folio even without FW_ZEROPAGE set.\n  Callers seem to tolerate that, though.\n\n... and triggering the VM_WARN_ON_ONE(), although never reported so far.\n\nTo fix it, teach vm_normal_page_pmd()/vm_normal_page_pud() to consider\nwhether pmd_special/pud_special is actually implemented.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-19 16:18:00","updated_at":"2026-07-19 16:18:00"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/62153767e8fc3889bc6508e9ffe927aaf64c4334","name":"https://git.kernel.org/stable/c/62153767e8fc3889bc6508e9ffe927aaf64c4334","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/9052ea2ee2233be5d4786b8909151ca2bfbedf99","name":"https://git.kernel.org/stable/c/9052ea2ee2233be5d4786b8909151ca2bfbedf99","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c0c6ccd9828c3a1950623b546fa57292a77b5c73","name":"https://git.kernel.org/stable/c/c0c6ccd9828c3a1950623b546fa57292a77b5c73","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-64181","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64181","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected af38538801c6a97565b44700ee6695d7d60ad779 62153767e8fc3889bc6508e9ffe927aaf64c4334 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected af38538801c6a97565b44700ee6695d7d60ad779 9052ea2ee2233be5d4786b8909151ca2bfbedf99 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected af38538801c6a97565b44700ee6695d7d60ad779 c0c6ccd9828c3a1950623b546fa57292a77b5c73 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.18","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.34 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0.11 7.0.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["mm/memory.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"62153767e8fc3889bc6508e9ffe927aaf64c4334","status":"affected","version":"af38538801c6a97565b44700ee6695d7d60ad779","versionType":"git"},{"lessThan":"9052ea2ee2233be5d4786b8909151ca2bfbedf99","status":"affected","version":"af38538801c6a97565b44700ee6695d7d60ad779","versionType":"git"},{"lessThan":"c0c6ccd9828c3a1950623b546fa57292a77b5c73","status":"affected","version":"af38538801c6a97565b44700ee6695d7d60ad779","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["mm/memory.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.18"},{"lessThan":"6.18","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.34","versionType":"semver"},{"lessThanOrEqual":"7.0.*","status":"unaffected","version":"7.0.11","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.34","versionStartIncluding":"6.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0.11","versionStartIncluding":"6.18","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1","versionStartIncluding":"6.18","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special()\n\nOn x86 32-bit with THP enabled, zap_huge_pmd() is seen to generate a\n\"WARNING: mm/memory.c:735 at __vm_normal_page+0x6a/0x7d\", from the\nVM_WARN_ON_ONCE(is_zero_pfn(pfn) || is_huge_zero_pfn(pfn)); followed by\n\"BUG: Bad rss-counter state\"s, then later \"BUG: Bad page state\"s when\nreclaim gets to call shrink_huge_zero_folio_scan().\n\nIt's as if the _PAGE_SPECIAL bit never got set in the huge_zero pmd: and\nindeed, whereas pte_special() and pte_mkspecial() are subject to a\ndedicated CONFIG_ARCH_HAS_PTE_SPECIAL, pmd_special() and pmd_mkspecial()\nare subject to CONFIG_ARCH_SUPPORTS_PMD_PFNMAP, which is never enabled on\nany 32-bit architecture.\n\nWhile the problem was exposed through commit d80a9cb1a64a\n(\"mm/huge_memory: add and use normal_or_softleaf_folio_pmd()\"), it was an\noversight in commit af38538801c6 (\"mm/memory: factor out common code from\nvm_normal_page_*()\") and would result in other problems:\n* huge zero folio accounted in smaps, pagemap (PAGE_IS_FILE) and\n  numamaps as file-backed THP\n* folio_walk_start() returning the folio even without FW_ZEROPAGE set.\n  Callers seem to tolerate that, though.\n\n... and triggering the VM_WARN_ON_ONE(), although never reported so far.\n\nTo fix it, teach vm_normal_page_pmd()/vm_normal_page_pud() to consider\nwhether pmd_special/pud_special is actually implemented."}],"providerMetadata":{"dateUpdated":"2026-07-19T15:41:04.455Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/62153767e8fc3889bc6508e9ffe927aaf64c4334"},{"url":"https://git.kernel.org/stable/c/9052ea2ee2233be5d4786b8909151ca2bfbedf99"},{"url":"https://git.kernel.org/stable/c/c0c6ccd9828c3a1950623b546fa57292a77b5c73"}],"title":"mm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-64181","datePublished":"2026-07-19T15:41:04.455Z","dateReserved":"2026-07-19T07:54:57.039Z","dateUpdated":"2026-07-19T15:41:04.455Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-19 16:18:00","lastModifiedDate":"2026-07-19 16:18:00","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"64181","Ordinal":"1","Title":"mm: fix __vm_normal_page() to handle missing support for pmd_spe","CVE":"CVE-2026-64181","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"64181","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special()\n\nOn x86 32-bit with THP enabled, zap_huge_pmd() is seen to generate a\n\"WARNING: mm/memory.c:735 at __vm_normal_page+0x6a/0x7d\", from the\nVM_WARN_ON_ONCE(is_zero_pfn(pfn) || is_huge_zero_pfn(pfn)); followed by\n\"BUG: Bad rss-counter state\"s, then later \"BUG: Bad page state\"s when\nreclaim gets to call shrink_huge_zero_folio_scan().\n\nIt's as if the _PAGE_SPECIAL bit never got set in the huge_zero pmd: and\nindeed, whereas pte_special() and pte_mkspecial() are subject to a\ndedicated CONFIG_ARCH_HAS_PTE_SPECIAL, pmd_special() and pmd_mkspecial()\nare subject to CONFIG_ARCH_SUPPORTS_PMD_PFNMAP, which is never enabled on\nany 32-bit architecture.\n\nWhile the problem was exposed through commit d80a9cb1a64a\n(\"mm/huge_memory: add and use normal_or_softleaf_folio_pmd()\"), it was an\noversight in commit af38538801c6 (\"mm/memory: factor out common code from\nvm_normal_page_*()\") and would result in other problems:\n* huge zero folio accounted in smaps, pagemap (PAGE_IS_FILE) and\n  numamaps as file-backed THP\n* folio_walk_start() returning the folio even without FW_ZEROPAGE set.\n  Callers seem to tolerate that, though.\n\n... and triggering the VM_WARN_ON_ONE(), although never reported so far.\n\nTo fix it, teach vm_normal_page_pmd()/vm_normal_page_pud() to consider\nwhether pmd_special/pud_special is actually implemented.","Type":"Description","Title":"mm: fix __vm_normal_page() to handle missing support for pmd_spe"}]}}}