Upstream information
Description
In the Linux kernel, the following vulnerability has been resolved:mm/hugetlb: fix hugetlb_pmd_shared()
Patch series "mm/hugetlb: fixes for PMD table sharing (incl. using
mmu_gather)", v3.
One functional fix, one performance regression fix, and two related
comment fixes.
I cleaned up my prototype I recently shared [1] for the performance fix,
deferring most of the cleanups I had in the prototype to a later point.
While doing that I identified the other things.
The goal of this patch set is to be backported to stable trees "fairly"
easily. At least patch #1 and #4.
Patch #1 fixes hugetlb_pmd_shared() not detecting any sharing
Patch #2 + #3 are simple comment fixes that patch #4 interacts with.
Patch #4 is a fix for the reported performance regression due to excessive
IPI broadcasts during fork()+exit().
The last patch is all about TLB flushes, IPIs and mmu_gather.
Read: complicated
There are plenty of cleanups in the future to be had + one reasonable
optimization on x86. But that's all out of scope for this series.
Runtime tested, with a focus on fixing the performance regression using
the original reproducer [2] on x86.
This patch (of 4):
We switched from (wrongly) using the page count to an independent shared
count. Now, shared page tables have a refcount of 1 (excluding
speculative references) and instead use ptdesc->pt_share_count to identify
sharing.
We didn't convert hugetlb_pmd_shared(), so right now, we would never
detect a shared PMD table as such, because sharing/unsharing no longer
touches the refcount of a PMD table.
Page migration, like mbind() or migrate_pages() would allow for migrating
folios mapped into such shared PMD tables, even though the folios are not
exclusive. In smaps we would account them as "private" although they are
"shared", and we would be wrongly setting the PM_MMAP_EXCLUSIVE in the
pagemap interface.
Fix it by properly using ptdesc_pmd_is_shared() in hugetlb_pmd_shared().
SUSE information
Overall state of this security issue: Does not affect SUSE products
Note from the SUSE Security Team on the kernel-default package
SUSE will no longer fix all CVEs in the Linux Kernel anymore, but declare some bug classes as won't fix. Please refer to TID 21496 for more details. SUSE Bugzilla entry: 1257817 [IN_PROGRESS]SUSE Security Advisories:
- SUSE-SU-2026:20838-1, published 2026-03-25T08:52:20Z
- SUSE-SU-2026:20873-1, published 2026-03-25T08:43:53Z
- SUSE-SU-2026:20931-1, published 2026-03-25T08:49:52Z
- SUSE-SU-2026:21284-1, published 2026-04-22T11:14:23Z
List of released packages
| Product(s) | Fixed package version(s) | References |
|---|---|---|
| Container suse/sl-micro/6.1/baremetal-os-container:2.2.1-7.67 Container suse/sl-micro/6.1/base-os-container:2.2.1-5.89 Container suse/sl-micro/6.1/kvm-os-container:2.2.1-5.92 Container suse/sl-micro/6.1/rt-os-container:2.2.1-5.81 |
| |
| Image SL-Micro-Azure Image SL-Micro-BYOS-Azure Image SL-Micro-BYOS-EC2 Image SL-Micro-BYOS-GCE Image SL-Micro-EC2 Image SUSE-Multi-Linux-Manager-Proxy-BYOS-Azure Image SUSE-Multi-Linux-Manager-Proxy-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Proxy-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-Azure-llc Image SUSE-Multi-Linux-Manager-Server-Azure-ltd Image SUSE-Multi-Linux-Manager-Server-BYOS-Azure Image SUSE-Multi-Linux-Manager-Server-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Server-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-EC2-llc Image SUSE-Multi-Linux-Manager-Server-EC2-ltd |
| |
| Image SLES-Azure-3P Image SLES-Azure-Basic Image SLES-Azure-Standard Image SLES-BYOS-Azure Image SLES-BYOS-EC2 Image SLES-BYOS-GCE Image SLES-CHOST-BYOS-GDC Image SLES-CHOST-BYOS-SAP-CCloud Image SLES-EC2 Image SLES-GCE Image SLES-GCE-3P Image SLES-Hardened-BYOS-Azure Image SLES-Hardened-BYOS-EC2 Image SLES-Hardened-BYOS-GCE Image SLES-SAPCAL-Azure Image SLES-SAPCAL-EC2 Image SLES-SAPCAL-GCE |
| |
| Image SLES-SAP-Azure Image SLES-SAP-Azure-3P Image SLES-SAP-BYOS-Azure Image SLES-SAP-BYOS-EC2 Image SLES-SAP-BYOS-GCE Image SLES-SAP-EC2 Image SLES-SAP-GCE Image SLES-SAP-GCE-3P |
| |
| SUSE Linux Enterprise High Availability Extension 16.0 |
| Patchnames: SUSE-SLES-HA-16.0-435 |
| SUSE Linux Enterprise Server 16.0 |
| Patchnames: SUSE-SLES-16.0-435 |
| SUSE Linux Enterprise Server for SAP applications 16.0 |
| Patchnames: SUSE-SLES-16.0-435 |
| SUSE Linux Micro 6.2 |
| Patchnames: SUSE-SL-Micro-6.2-435 |
| openSUSE Leap 16.0 |
| Patchnames: openSUSE-Leap-16.0-435 |
List of packages in QA
| Product(s) | Package(s) |
|---|---|
| SUSE Linux Enterprise Server 16.0 |
|
Status of this issue by product and package
Please note that this evaluation state might be work in progress, incomplete or outdated. Also information for service packs in the LTSS phase is only included for issues meeting the LTSS criteria. If in doubt, feel free to contact us for clarification. The updates are grouped by state of their lifecycle. SUSE product lifecycles are documented on the lifecycle page.
| Product(s) | Source package | State |
|---|---|---|
| Products under general support and receiving all security fixes. | ||
| SUSE Linux Enterprise High Availability Extension 16.0 | kernel-default | Released |
| SUSE Linux Enterprise Server 16.0 | kernel-64kb | In progress |
| SUSE Linux Enterprise Server 16.0 | kernel-azure | In progress |
| SUSE Linux Enterprise Server 16.0 | kernel-default | In progress |
| SUSE Linux Enterprise Server 16.0 | kernel-default-base | In progress |
| SUSE Linux Enterprise Server 16.0 | kernel-docs | In progress |
| SUSE Linux Enterprise Server 16.0 | kernel-kvmsmall | In progress |
| SUSE Linux Enterprise Server 16.0 | kernel-obs-qa | In progress |
| SUSE Linux Enterprise Server 16.0 | kernel-source | In progress |
| SUSE Linux Enterprise Server 16.0 | kernel-syms | In progress |
| SUSE Linux Enterprise Server 16.0 | kernel-zfcpdump | In progress |
| SUSE Linux Enterprise Server for SAP applications 16.0 | kernel-azure | Released |
| SUSE Linux Enterprise Server for SAP applications 16.0 | kernel-default | Released |
| SUSE Linux Enterprise Server for SAP applications 16.0 | kernel-default-base | Released |
| SUSE Linux Enterprise Server for SAP applications 16.0 | kernel-docs | Released |
| SUSE Linux Enterprise Server for SAP applications 16.0 | kernel-kvmsmall | Released |
| SUSE Linux Enterprise Server for SAP applications 16.0 | kernel-obs-qa | Released |
| SUSE Linux Enterprise Server for SAP applications 16.0 | kernel-source | Released |
| SUSE Linux Enterprise Server for SAP applications 16.0 | kernel-syms | Released |
| SUSE Linux Micro 6.2 | kernel-64kb | Released |
| SUSE Linux Micro 6.2 | kernel-default | Released |
| SUSE Linux Micro 6.2 | kernel-default-base | Released |
| SUSE Linux Micro 6.2 | kernel-rt | Released |
| SUSE Linux Micro 6.2 | kernel-source | Released |
SUSE Timeline for this CVE
CVE page created: Wed Feb 4 20:04:18 2026CVE page last modified: Fri May 8 12:01:20 2026