{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-89756", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.763Z", "datePublished": "2026-09-11T19:46:59.093Z", "dateUpdated": "2026-09-11T19:46:59.093Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-09-11T19:46:59.093Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/migrate: report RCU-tasks quiescent states in migrate_pages_batch()\n\nmigrate_pages_batch() unmaps each folio before moving it, and every\nunmap runs the mmu_notifier invalidate callbacks. On KVM hosts\ntry_to_migrate() ends up in kvm_mmu_notifier_invalidate_range_start() ->\ntdp_mmu_zap_leafs(), which is expensive, so unmapping a large batch keeps\nthe CPU busy for a long time.\n\nThe loop already calls cond_resched(), but on PREEMPTION kernels that is\na no-op, and involuntary preemption is not a Tasks-RCU quiescent state.\n\nA long batch therefore never reports a quiescent state, and the\nmigrating task (e.g. kcompactd) becomes a Tasks-RCU holdout, stalling the\nTasks-RCU grace period for minutes, which is common at Meta fleet:\n\n INFO: rcu_tasks detected stalls on tasks:\n 0000000055349ecc: .. nvcsw: 1157401/1157401 holdout: 1 idle_cpu: -1/56 task:kcompactd0 state:R running task\n Call Trace:\n tdp_mmu_zap_leafs\n tdp_mmu_next_root\n gfn_to_pfn_cache_invalidate_start\n kvm_mmu_notifier_invalidate_range_start\n __mmu_notifier_invalidate_range_start\n try_to_migrate_one\n try_to_migrate\n migrate_pages_batch\n migrate_pages\n compact_zone\n compact_node\n kcompactd\n kthread\n\nUse cond_resched_tasks_rcu_qs() so a quiescent state is reported even\nwhen cond_resched() does nothing.\n\nThis has also been discussed at [1]"}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["mm/migrate.c"], "versions": [{"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "4996a7bc01ef35570664854dac2530c604981039", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "5dc0daff0341c6baba19c38f47d299ac831d7e99", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "66734981b4d3c105223a13c827c9c73be18d91ad", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "efe8f86c0916f0f74eea74ae21a3b37f728c6bad", "status": "affected", "versionType": "git"}, {"version": "0", "lessThan": "6.12.109", "status": "affected", "versionType": "semver"}, {"version": "0", "lessThan": "6.18.50", "status": "affected", "versionType": "semver"}, {"version": "0", "lessThan": "7.2.4", "status": "affected", "versionType": "semver"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["mm/migrate.c"], "versions": [{"version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3-rc1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.12.109"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "6.18.50"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "7.2.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionEndExcluding": "7.3-rc1"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/4996a7bc01ef35570664854dac2530c604981039"}, {"url": "https://git.kernel.org/stable/c/5dc0daff0341c6baba19c38f47d299ac831d7e99"}, {"url": "https://git.kernel.org/stable/c/66734981b4d3c105223a13c827c9c73be18d91ad"}, {"url": "https://git.kernel.org/stable/c/efe8f86c0916f0f74eea74ae21a3b37f728c6bad"}], "title": "mm/migrate: report RCU-tasks quiescent states in migrate_pages_batch()", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["mm/migrate.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "4996a7bc01ef35570664854dac2530c604981039", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "5dc0daff0341c6baba19c38f47d299ac831d7e99", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "66734981b4d3c105223a13c827c9c73be18d91ad", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "efe8f86c0916f0f74eea74ae21a3b37f728c6bad", "status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "versionType": "git"}, {"lessThan": "6.12.109", "status": "affected", "version": "0", "versionType": "semver"}, {"lessThan": "6.18.50", "status": "affected", "version": "0", "versionType": "semver"}, {"lessThan": "7.2.4", "status": "affected", "version": "0", "versionType": "semver"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["mm/migrate.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.109", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.50", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.4", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3-rc1", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/migrate: report RCU-tasks quiescent states in migrate_pages_batch()\n\nmigrate_pages_batch() unmaps each folio before moving it, and every\nunmap runs the mmu_notifier invalidate callbacks. On KVM hosts\ntry_to_migrate() ends up in kvm_mmu_notifier_invalidate_range_start() ->\ntdp_mmu_zap_leafs(), which is expensive, so unmapping a large batch keeps\nthe CPU busy for a long time.\n\nThe loop already calls cond_resched(), but on PREEMPTION kernels that is\na no-op, and involuntary preemption is not a Tasks-RCU quiescent state.\n\nA long batch therefore never reports a quiescent state, and the\nmigrating task (e.g. kcompactd) becomes a Tasks-RCU holdout, stalling the\nTasks-RCU grace period for minutes, which is common at Meta fleet:\n\n INFO: rcu_tasks detected stalls on tasks:\n 0000000055349ecc: .. nvcsw: 1157401/1157401 holdout: 1 idle_cpu: -1/56 task:kcompactd0 state:R running task\n Call Trace:\n tdp_mmu_zap_leafs\n tdp_mmu_next_root\n gfn_to_pfn_cache_invalidate_start\n kvm_mmu_notifier_invalidate_range_start\n __mmu_notifier_invalidate_range_start\n try_to_migrate_one\n try_to_migrate\n migrate_pages_batch\n migrate_pages\n compact_zone\n compact_node\n kcompactd\n kthread\n\nUse cond_resched_tasks_rcu_qs() so a quiescent state is reported even\nwhen cond_resched() does nothing.\n\nThis has also been discussed at [1]"}], "id": "CVE-2026-89756", "lastModified": "2026-09-11T20:20:06.643", "metrics": {}, "published": "2026-09-11T20:20:06.643", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4996a7bc01ef35570664854dac2530c604981039"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/5dc0daff0341c6baba19c38f47d299ac831d7e99"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/66734981b4d3c105223a13c827c9c73be18d91ad"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/efe8f86c0916f0f74eea74ae21a3b37f728c6bad"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: Linux kernel: Denial of Service due to RCU-tasks stall during memory migration", "id": "2532146", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2532146"}, "csaw": false, "cvss3": {"cvss3_base_score": "4.7", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-821", "details": ["A flaw was found in the Linux kernel. When performing memory migration on KVM (Kernel-based Virtual Machine) hosts, the `migrate_pages_batch()` function fails to report RCU (Read-Copy Update) tasks quiescent states during large batch unmapping operations. This oversight causes the migrating task to become an RCU holdout, leading to a prolonged stall in the RCU grace period. This can result in a Denial of Service (DoS) by keeping the CPU busy for an extended duration."], "name": "CVE-2026-89756", "public_date": "2026-09-11T19:46:59Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-89756\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-89756\nhttps://git.kernel.org/stable/c/4996a7bc01ef35570664854dac2530c604981039\nhttps://git.kernel.org/stable/c/5dc0daff0341c6baba19c38f47d299ac831d7e99\nhttps://git.kernel.org/stable/c/66734981b4d3c105223a13c827c9c73be18d91ad\nhttps://git.kernel.org/stable/c/efe8f86c0916f0f74eea74ae21a3b37f728c6bad"], "threat_severity": "Moderate"}

{"created": "2026-09-12T06:15:04.245971+00:00", "updated": "2026-09-12T12:15:13.352675+00:00", "vendors": []}