{"api_version":"1","generated_at":"2026-09-12T02:59:37+00:00","cve":"CVE-2026-89756","urls":{"html":"https://cve.report/CVE-2026-89756","api":"https://cve.report/api/cve/CVE-2026-89756.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89756","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89756"},"summary":{"title":"mm/migrate: report RCU-tasks quiescent states in migrate_pages_batch()","description":"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]","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:20:06","updated_at":"2026-09-11 20:20:06"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/efe8f86c0916f0f74eea74ae21a3b37f728c6bad","name":"https://git.kernel.org/stable/c/efe8f86c0916f0f74eea74ae21a3b37f728c6bad","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/66734981b4d3c105223a13c827c9c73be18d91ad","name":"https://git.kernel.org/stable/c/66734981b4d3c105223a13c827c9c73be18d91ad","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/5dc0daff0341c6baba19c38f47d299ac831d7e99","name":"https://git.kernel.org/stable/c/5dc0daff0341c6baba19c38f47d299ac831d7e99","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4996a7bc01ef35570664854dac2530c604981039","name":"https://git.kernel.org/stable/c/4996a7bc01ef35570664854dac2530c604981039","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89756","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89756","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 4996a7bc01ef35570664854dac2530c604981039 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 5dc0daff0341c6baba19c38f47d299ac831d7e99 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 66734981b4d3c105223a13c827c9c73be18d91ad git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 efe8f86c0916f0f74eea74ae21a3b37f728c6bad git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.12.109 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.18.50 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.2.4 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.109 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.50 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.4 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * 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/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"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"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","vulnerable":true}],"negate":false,"operator":"OR"}]}],"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]"}],"providerMetadata":{"dateUpdated":"2026-09-11T19:46:59.093Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"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"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89756","datePublished":"2026-09-11T19:46:59.093Z","dateReserved":"2026-09-11T19:38:34.763Z","dateUpdated":"2026-09-11T19:46:59.093Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:20:06","lastModifiedDate":"2026-09-11 20:20:06","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89756","Ordinal":"1","Title":"mm/migrate: report RCU-tasks quiescent states in migrate_pages_b","CVE":"CVE-2026-89756","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89756","Ordinal":"1","NoteData":"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]","Type":"Description","Title":"mm/migrate: report RCU-tasks quiescent states in migrate_pages_b"}]}}}