{"api_version":"1","generated_at":"2026-04-23T02:58:04+00:00","cve":"CVE-2026-31466","urls":{"html":"https://cve.report/CVE-2026-31466","api":"https://cve.report/api/cve/CVE-2026-31466.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-31466","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-31466"},"summary":{"title":"mm/huge_memory: fix folio isn't locked in softleaf_to_folio()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/huge_memory: fix folio isn't locked in softleaf_to_folio()\n\nOn arm64 server, we found folio that get from migration entry isn't locked\nin softleaf_to_folio().  This issue triggers when mTHP splitting and\nzap_nonpresent_ptes() races, and the root cause is lack of memory barrier\nin softleaf_to_folio().  The race is as follows:\n\n\tCPU0                                             CPU1\n\ndeferred_split_scan()                              zap_nonpresent_ptes()\n  lock folio\n  split_folio()\n    unmap_folio()\n      change ptes to migration entries\n    __split_folio_to_order()                         softleaf_to_folio()\n      set flags(including PG_locked) for tail pages    folio = pfn_folio(softleaf_to_pfn(entry))\n      smp_wmb()                                        VM_WARN_ON_ONCE(!folio_test_locked(folio))\n      prep_compound_page() for tail pages\n\nIn __split_folio_to_order(), smp_wmb() guarantees page flags of tail pages\nare visible before the tail page becomes non-compound.  smp_wmb() should\nbe paired with smp_rmb() in softleaf_to_folio(), which is missed.  As a\nresult, if zap_nonpresent_ptes() accesses migration entry that stores tail\npfn, softleaf_to_folio() may see the updated compound_head of tail page\nbefore page->flags.\n\nThis issue will trigger VM_WARN_ON_ONCE() in pfn_swap_entry_folio()\nbecause of the race between folio split and zap_nonpresent_ptes()\nleading to a folio incorrectly undergoing modification without a folio\nlock being held.\n\nThis is a BUG_ON() before commit 93976a20345b (\"mm: eliminate further\nswapops predicates\"), which in merged in v6.19-rc1.\n\nTo fix it, add missing smp_rmb() if the softleaf entry is migration entry\nin softleaf_to_folio() and softleaf_to_page().\n\n[tujinjiang@huawei.com: update function name and comments]","state":"PUBLISHED","assigner":"Linux","published_at":"2026-04-22 14:16:42","updated_at":"2026-04-22 14:16:42"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/426ee10711586617da869c8bb798214965337617","name":"https://git.kernel.org/stable/c/426ee10711586617da869c8bb798214965337617","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f1acf5887c2bbaf998dc3fe32c72b7a8b84a3ddd","name":"https://git.kernel.org/stable/c/f1acf5887c2bbaf998dc3fe32c72b7a8b84a3ddd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4c5e7f0fcd592801c9cc18f29f80fbee84eb8669","name":"https://git.kernel.org/stable/c/4c5e7f0fcd592801c9cc18f29f80fbee84eb8669","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b8c49ad888892ad7b77062b9c102b799a3e9b4f8","name":"https://git.kernel.org/stable/c/b8c49ad888892ad7b77062b9c102b799a3e9b4f8","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/722cfaf6b31d31123439e67b5deac6b1261a3dea","name":"https://git.kernel.org/stable/c/722cfaf6b31d31123439e67b5deac6b1261a3dea","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7ad1997b9bc8032603df8f091761114479285769","name":"https://git.kernel.org/stable/c/7ad1997b9bc8032603df8f091761114479285769","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/8bfb8414e9f2ce6f5f2f0e3d0da52f2d132128e7","name":"https://git.kernel.org/stable/c/8bfb8414e9f2ce6f5f2f0e3d0da52f2d132128e7","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7ddcf4a245c1c5a91fdd9698757e3d95179ffe41","name":"https://git.kernel.org/stable/c/7ddcf4a245c1c5a91fdd9698757e3d95179ffe41","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-31466","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31466","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e9b61f19858a5d6c42ce2298cf138279375d0d9b 426ee10711586617da869c8bb798214965337617 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e9b61f19858a5d6c42ce2298cf138279375d0d9b f1acf5887c2bbaf998dc3fe32c72b7a8b84a3ddd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e9b61f19858a5d6c42ce2298cf138279375d0d9b 722cfaf6b31d31123439e67b5deac6b1261a3dea git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e9b61f19858a5d6c42ce2298cf138279375d0d9b 7ddcf4a245c1c5a91fdd9698757e3d95179ffe41 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e9b61f19858a5d6c42ce2298cf138279375d0d9b b8c49ad888892ad7b77062b9c102b799a3e9b4f8 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e9b61f19858a5d6c42ce2298cf138279375d0d9b 7ad1997b9bc8032603df8f091761114479285769 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e9b61f19858a5d6c42ce2298cf138279375d0d9b 8bfb8414e9f2ce6f5f2f0e3d0da52f2d132128e7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e9b61f19858a5d6c42ce2298cf138279375d0d9b 4c5e7f0fcd592801c9cc18f29f80fbee84eb8669 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4.5","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 4.5 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.10.253 5.10.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.203 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.168 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.134 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.81 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.21 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.19.11 6.19.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0 * 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":["include/linux/leafops.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"426ee10711586617da869c8bb798214965337617","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"},{"lessThan":"f1acf5887c2bbaf998dc3fe32c72b7a8b84a3ddd","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"},{"lessThan":"722cfaf6b31d31123439e67b5deac6b1261a3dea","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"},{"lessThan":"7ddcf4a245c1c5a91fdd9698757e3d95179ffe41","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"},{"lessThan":"b8c49ad888892ad7b77062b9c102b799a3e9b4f8","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"},{"lessThan":"7ad1997b9bc8032603df8f091761114479285769","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"},{"lessThan":"8bfb8414e9f2ce6f5f2f0e3d0da52f2d132128e7","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"},{"lessThan":"4c5e7f0fcd592801c9cc18f29f80fbee84eb8669","status":"affected","version":"e9b61f19858a5d6c42ce2298cf138279375d0d9b","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["include/linux/leafops.h"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"4.5"},{"lessThan":"4.5","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.10.*","status":"unaffected","version":"5.10.253","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.203","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.168","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.134","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.81","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.21","versionType":"semver"},{"lessThanOrEqual":"6.19.*","status":"unaffected","version":"6.19.11","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.0","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.10.253","versionStartIncluding":"4.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.203","versionStartIncluding":"4.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.168","versionStartIncluding":"4.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.134","versionStartIncluding":"4.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.81","versionStartIncluding":"4.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.21","versionStartIncluding":"4.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.19.11","versionStartIncluding":"4.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0","versionStartIncluding":"4.5","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/huge_memory: fix folio isn't locked in softleaf_to_folio()\n\nOn arm64 server, we found folio that get from migration entry isn't locked\nin softleaf_to_folio().  This issue triggers when mTHP splitting and\nzap_nonpresent_ptes() races, and the root cause is lack of memory barrier\nin softleaf_to_folio().  The race is as follows:\n\n\tCPU0                                             CPU1\n\ndeferred_split_scan()                              zap_nonpresent_ptes()\n  lock folio\n  split_folio()\n    unmap_folio()\n      change ptes to migration entries\n    __split_folio_to_order()                         softleaf_to_folio()\n      set flags(including PG_locked) for tail pages    folio = pfn_folio(softleaf_to_pfn(entry))\n      smp_wmb()                                        VM_WARN_ON_ONCE(!folio_test_locked(folio))\n      prep_compound_page() for tail pages\n\nIn __split_folio_to_order(), smp_wmb() guarantees page flags of tail pages\nare visible before the tail page becomes non-compound.  smp_wmb() should\nbe paired with smp_rmb() in softleaf_to_folio(), which is missed.  As a\nresult, if zap_nonpresent_ptes() accesses migration entry that stores tail\npfn, softleaf_to_folio() may see the updated compound_head of tail page\nbefore page->flags.\n\nThis issue will trigger VM_WARN_ON_ONCE() in pfn_swap_entry_folio()\nbecause of the race between folio split and zap_nonpresent_ptes()\nleading to a folio incorrectly undergoing modification without a folio\nlock being held.\n\nThis is a BUG_ON() before commit 93976a20345b (\"mm: eliminate further\nswapops predicates\"), which in merged in v6.19-rc1.\n\nTo fix it, add missing smp_rmb() if the softleaf entry is migration entry\nin softleaf_to_folio() and softleaf_to_page().\n\n[tujinjiang@huawei.com: update function name and comments]"}],"providerMetadata":{"dateUpdated":"2026-04-22T13:53:56.259Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/426ee10711586617da869c8bb798214965337617"},{"url":"https://git.kernel.org/stable/c/f1acf5887c2bbaf998dc3fe32c72b7a8b84a3ddd"},{"url":"https://git.kernel.org/stable/c/722cfaf6b31d31123439e67b5deac6b1261a3dea"},{"url":"https://git.kernel.org/stable/c/7ddcf4a245c1c5a91fdd9698757e3d95179ffe41"},{"url":"https://git.kernel.org/stable/c/b8c49ad888892ad7b77062b9c102b799a3e9b4f8"},{"url":"https://git.kernel.org/stable/c/7ad1997b9bc8032603df8f091761114479285769"},{"url":"https://git.kernel.org/stable/c/8bfb8414e9f2ce6f5f2f0e3d0da52f2d132128e7"},{"url":"https://git.kernel.org/stable/c/4c5e7f0fcd592801c9cc18f29f80fbee84eb8669"}],"title":"mm/huge_memory: fix folio isn't locked in softleaf_to_folio()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-31466","datePublished":"2026-04-22T13:53:56.259Z","dateReserved":"2026-03-09T15:48:24.097Z","dateUpdated":"2026-04-22T13:53:56.259Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-04-22 14:16:42","lastModifiedDate":"2026-04-22 14:16:42","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"31466","Ordinal":"1","Title":"mm/huge_memory: fix folio isn't locked in softleaf_to_folio()","CVE":"CVE-2026-31466","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"31466","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/huge_memory: fix folio isn't locked in softleaf_to_folio()\n\nOn arm64 server, we found folio that get from migration entry isn't locked\nin softleaf_to_folio().  This issue triggers when mTHP splitting and\nzap_nonpresent_ptes() races, and the root cause is lack of memory barrier\nin softleaf_to_folio().  The race is as follows:\n\n\tCPU0                                             CPU1\n\ndeferred_split_scan()                              zap_nonpresent_ptes()\n  lock folio\n  split_folio()\n    unmap_folio()\n      change ptes to migration entries\n    __split_folio_to_order()                         softleaf_to_folio()\n      set flags(including PG_locked) for tail pages    folio = pfn_folio(softleaf_to_pfn(entry))\n      smp_wmb()                                        VM_WARN_ON_ONCE(!folio_test_locked(folio))\n      prep_compound_page() for tail pages\n\nIn __split_folio_to_order(), smp_wmb() guarantees page flags of tail pages\nare visible before the tail page becomes non-compound.  smp_wmb() should\nbe paired with smp_rmb() in softleaf_to_folio(), which is missed.  As a\nresult, if zap_nonpresent_ptes() accesses migration entry that stores tail\npfn, softleaf_to_folio() may see the updated compound_head of tail page\nbefore page->flags.\n\nThis issue will trigger VM_WARN_ON_ONCE() in pfn_swap_entry_folio()\nbecause of the race between folio split and zap_nonpresent_ptes()\nleading to a folio incorrectly undergoing modification without a folio\nlock being held.\n\nThis is a BUG_ON() before commit 93976a20345b (\"mm: eliminate further\nswapops predicates\"), which in merged in v6.19-rc1.\n\nTo fix it, add missing smp_rmb() if the softleaf entry is migration entry\nin softleaf_to_folio() and softleaf_to_page().\n\n[tujinjiang@huawei.com: update function name and comments]","Type":"Description","Title":"mm/huge_memory: fix folio isn't locked in softleaf_to_folio()"}]}}}