hugetlb: only adjust reservation during unmapping if mapcount is 0
Published Sep 11, 2026
7.1
HIGHCVSS 3.1
EPSS 0.13%
Description
Since df7a6d1f6405, __unmap_hugepage_range can adjust reservations. In the case of folio mapped in both a parent and a child, if the parent unmaps the range first, the reservation adjustment will result in an underflow of the reserved count. Once the child unmaps the range, the count is restored. Change __unmap_hugepage_range() to check the mapcount before adjusting the reservation.
Affected products
-
- Version StatusaffectedConstraints
- Version StatusaffectedConstraints
- Version StatusaffectedConstraints
- Version StatusaffectedConstraints
- Version
-
- Version 6.9StatusaffectedConstraints-
- Version 0StatusunaffectedConstraints<6.9
- Version 6.12.110StatusunaffectedConstraints<=6.12.*
- Version 6.18.50StatusunaffectedConstraints<=6.18.*
- Version 7.2.4StatusunaffectedConstraints<=7.2.*
- Version 7.3-rc1StatusunaffectedConstraints<=*
- Version
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
No data.
No data.
Red Hat Enterprise Linux 10
kernel
Fix deferred
Red Hat Enterprise Linux 10
kernel-rt
Fix deferred
Red Hat Enterprise Linux 6
kernel
Out of support scope
Red Hat Enterprise Linux 7
kernel
Not affected
Red Hat Enterprise Linux 7
kernel-rt
Not affected
Red Hat Enterprise Linux 8
kernel
Not affected
Red Hat Enterprise Linux 8
kernel-rt
Not affected
Red Hat Enterprise Linux 9
kernel
Fix deferred
Red Hat Enterprise Linux 9
kernel-rt
Fix deferred
Red Hat OpenShift Container Platform 4
openshift/ose-rhel-coreos-8
Not affected
Red Hat OpenShift Container Platform 4
openshift/ose-rhel-coreos-9
Fix deferred
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Fix deferred | n/a |
| Red Hat Enterprise Linux 10 | kernel-rt | Fix deferred | n/a |
| Red Hat Enterprise Linux 6 | kernel | Out of support scope | n/a |
| Red Hat Enterprise Linux 7 | kernel | Not affected | n/a |
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | n/a |
| Red Hat Enterprise Linux 8 | kernel | Not affected | n/a |
| Red Hat Enterprise Linux 8 | kernel-rt | Not affected | n/a |
| Red Hat Enterprise Linux 9 | kernel | Fix deferred | n/a |
| Red Hat Enterprise Linux 9 | kernel-rt | Fix deferred | n/a |
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-8 | Not affected | n/a |
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-9 | Fix deferred | n/a |
No package ranges for this CVE.
Remediation
No remediation recorded yet.
References (10)
- https://access.redhat.com/security/cve/CVE-2026-89593 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2532027 Issue Tracking
- https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-76505 Advisory
- https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89593.mbox
- https://git.kernel.org/stable/c/0f001491e5a2ec69aa9d5dd6b799e5742245f9ea
- https://git.kernel.org/stable/c/5120b1e048d48596ffaec1a8412012a91adba73b
- https://git.kernel.org/stable/c/a3c65af20cceb7f997847727636b4017326f845d
- https://git.kernel.org/stable/c/b0b1b9ca80b795ed2223e76dd787db7067121fb9
- https://nvd.nist.gov/vuln/detail/CVE-2026-89593
- https://www.cve.org/CVERecord?id=CVE-2026-89593
Change history (0)
No recorded changes yet.