CVE-2026-89756mm/migrate: report RCU-tasks quiescent states in migrate_pages_batch()
- —Not scoredno CVSS score yet
- 0.20%Exploitation in 30 daysEPSS · top 91% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: mm/migrate: report RCU-tasks quiescent states in migrate_pages_batch() migrate_pages_batch() unmaps each folio before moving it, and every unmap runs the mmu_notifier invalidate callbacks. On KVM hosts try_to_migrate() ends up in kvm_mmu_notifier_invalidate_range_start() -> tdp_mmu_zap_leafs(), which is expensive, so unmapping a large batch keeps the CPU busy for a long time. The loop already calls cond_resched(), but on PREEMPTION kernels that is a no-op, and involuntary preemption is not a Tasks-RCU quiescent state. A long batch therefore never reports a quiescent state, and the migrating task (e.g. kcompactd) becomes a Tasks-RCU holdout, stalling the Tasks-RCU grace period for minutes, which is common at Meta fleet: INFO: rcu_tasks detected stalls on tasks: 0000000055349ecc: .. nvcsw: 1157401/1157401 holdout: 1 idle_cpu: -1/56 task:kcompactd0 state:R running task Call Trace: tdp_mmu_zap_leafs tdp_mmu_next_root gfn_to_pfn_cache_invalidate_start kvm_mmu_notifier_invalidate_range_start __mmu_notifier_invalidate_range_start try_to_migrate_one try_to_migrate migrate_pages_batch migrate_pages compact_zone compact_node kcompactd kthread Use cond_resched_tasks_rcu_qs() so a quiescent state is reported even when cond_resched() does nothing. This has also been discussed at [1]
Timeline
ID reserved
By Linux
Published
- 38 days later
· 38 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.
- EPSS (exploitation in 30 days)
- 0.20% · top 91% of all CVEs (14 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.
Affected products
- affected 8315f42295d2667a7f942f154b73a86fd7cb2227 – < 8c6d63d434ebb85c6cf3dac1e70a171b183c6614
- affected 8315f42295d2667a7f942f154b73a86fd7cb2227 – < 4757542649af56d894e25e30f57cd497dffad53f
- affected 8315f42295d2667a7f942f154b73a86fd7cb2227 – < 4996a7bc01ef35570664854dac2530c604981039
- affected 8315f42295d2667a7f942f154b73a86fd7cb2227 – < 5dc0daff0341c6baba19c38f47d299ac831d7e99
- affected 8315f42295d2667a7f942f154b73a86fd7cb2227 – < 66734981b4d3c105223a13c827c9c73be18d91ad
- affected 8315f42295d2667a7f942f154b73a86fd7cb2227 – < efe8f86c0916f0f74eea74ae21a3b37f728c6bad
- affected 3.18
- unaffected < 3.18
- unaffected 6.1.188 – ≤ 6.1.*
- unaffected 6.6.157 – ≤ 6.6.*
- unaffected 6.12.109 – ≤ 6.12.*
- unaffected 6.18.50 – ≤ 6.18.*
- unaffected 7.2.4 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References6
- https://git.kernel.org/stable/c/8c6d63d434ebb85c6cf3dac1e70a171b183c6614 (opens in a new tab)
- https://git.kernel.org/stable/c/4757542649af56d894e25e30f57cd497dffad53f (opens in a new tab)
- https://git.kernel.org/stable/c/4996a7bc01ef35570664854dac2530c604981039 (opens in a new tab)
- https://git.kernel.org/stable/c/5dc0daff0341c6baba19c38f47d299ac831d7e99 (opens in a new tab)
- https://git.kernel.org/stable/c/66734981b4d3c105223a13c827c9c73be18d91ad (opens in a new tab)
- https://git.kernel.org/stable/c/efe8f86c0916f0f74eea74ae21a3b37f728c6bad (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-76668 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
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[](https://cveledger.app/cve/CVE-2026-89756)Record last updated .