Upstream information
Description
In the Linux kernel, the following vulnerability has been resolved:ksm: use range-walk function to jump over holes in scan_get_next_rmap_item
Currently, scan_get_next_rmap_item() walks every page address in a VMA to
locate mergeable pages. This becomes highly inefficient when scanning
large virtual memory areas that contain mostly unmapped regions, causing
ksmd to use large amount of cpu without deduplicating much pages.
This patch replaces the per-address lookup with a range walk using
walk_page_range(). The range walker allows KSM to skip over entire
unmapped holes in a VMA, avoiding unnecessary lookups. This problem was
previously discussed in [1].
Consider the following test program which creates a 32 TiB mapping in the
virtual address space but only populates a single page:
#include <unistd.h>
#include <stdio.h>
#include <sys/mman.h>
/* 32 TiB */
const size_t size = 32ul * 1024 * 1024 * 1024 * 1024;
int main() {
char *area = mmap(NULL, size, PROT_READ | PROT_WRITE,
MAP_NORESERVE | MAP_PRIVATE | MAP_ANON, -1, 0);
if (area == MAP_FAILED) {
perror("mmap() failed\n");
return -1;
}
/* Populate a single page such that we get an anon_vma. */
*area = 0;
/* Enable KSM. */
madvise(area, size, MADV_MERGEABLE);
pause();
return 0;
}
$ ./ksm-sparse &
$ echo 1 > /sys/kernel/mm/ksm/run
Without this patch ksmd uses 100% of the cpu for a long time (more then 1
hour in my test machine) scanning all the 32 TiB virtual address space
that contain only one mapped page. This makes ksmd essentially deadlocked
not able to deduplicate anything of value. With this patch ksmd walks
only the one mapped page and skips the rest of the 32 TiB virtual address
space, making the scan fast using little cpu.
SUSE information
Overall state of this security issue: New
This issue is currently rated as having not set severity.
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. No SUSE Bugzilla entries cross referenced. No SUSE Security Announcements cross referenced.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Please note that this evaluation state might be work in progress, incomplete or outdated.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 Desktop 15 SP6 | kernel-default | Analysis |
| SUSE Linux Enterprise Desktop 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Desktop 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise High Availability Extension 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise High Availability Extension 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise High Availability Extension 16.0 | kernel-default | Analysis |
| SUSE Linux Enterprise High Availability Extension 16.0 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | kernel-default | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | kernel-source-azure | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | kernel-source-azure | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP6 | kernel-default | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.2 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.2 | kernel-rt | Analysis |
| SUSE Linux Enterprise Micro 5.2 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.2 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Micro 5.3 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.3 | kernel-rt | Analysis |
| SUSE Linux Enterprise Micro 5.3 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.3 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Micro 5.4 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.4 | kernel-rt | Analysis |
| SUSE Linux Enterprise Micro 5.4 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.4 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Micro 5.5 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.5 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.5 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP6 | kernel-default | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP6 | kernel-default | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Legacy 15 SP6 | kernel-default | Analysis |
| SUSE Linux Enterprise Module for Legacy 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Legacy 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Module for Legacy 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Public Cloud 15 SP6 | kernel-source-azure | Analysis |
| SUSE Linux Enterprise Module for Public Cloud 15 SP7 | kernel-source-azure | Analysis |
| SUSE Linux Enterprise Real Time 15 SP6 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Real Time 15 SP7 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Server 15 SP6 | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP6 | kernel-source-azure | Analysis |
| SUSE Linux Enterprise Server 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP7 | kernel-source-azure | Analysis |
| SUSE Linux Enterprise Server 16.0 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | kernel-source-azure | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | kernel-source-azure | Analysis |
| SUSE Linux Enterprise Workstation Extension 15 SP6 | kernel-default | Analysis |
| SUSE Linux Enterprise Workstation Extension 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Workstation Extension 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Workstation Extension 15 SP7 | kernel-source | Analysis |
| SUSE Linux Micro 6.0 | kernel-default | Analysis |
| SUSE Linux Micro 6.0 | kernel-source | Analysis |
| SUSE Linux Micro 6.0 | kernel-source-rt | Analysis |
| SUSE Linux Micro 6.1 | kernel-default | Analysis |
| SUSE Linux Micro 6.1 | kernel-source | Analysis |
| SUSE Linux Micro 6.1 | kernel-source-rt | Analysis |
| SUSE Linux Micro 6.2 | kernel-source | Analysis |
| SUSE Real Time Module 15 SP6 | kernel-source-rt | Analysis |
| SUSE Real Time Module 15 SP7 | kernel-source-rt | Analysis |
| openSUSE Leap 15.6 | kernel-default | Analysis |
| openSUSE Leap 15.6 | kernel-source | Analysis |
| openSUSE Leap 15.6 | kernel-source-azure | Analysis |
| openSUSE Leap 15.6 | kernel-source-rt | Analysis |
| Products under Long Term Service Pack support and receiving important and critical security fixes. | ||
| SUSE Linux Enterprise High Availability Extension 15 SP3 | kernel-default | Analysis |
| SUSE Linux Enterprise High Availability Extension 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-default | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Live Patching 12 SP5 | kernel-default | Analysis |
| SUSE Linux Enterprise Live Patching 12 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP3 | kernel-default | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP4 | kernel-default | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP5 | kernel-default | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 11 SP4 LTSS EXTREME CORE | kernel-default | Analysis |
| SUSE Linux Enterprise Server 11 SP4 LTSS EXTREME CORE | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP5-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 12 SP5-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security | kernel-default | Analysis |
| SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP3-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP3-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP4-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP4-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP5-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP5-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 | kernel-source | Analysis |
| SUSE Manager Proxy 4.3 | kernel-source | Analysis |
| SUSE Manager Proxy LTS 4.3 | kernel-default | Analysis |
| SUSE Manager Proxy LTS 4.3 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server 4.3 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server LTS 4.3 | kernel-default | Analysis |
| SUSE Manager Retail Branch Server LTS 4.3 | kernel-source | Analysis |
| SUSE Manager Server 4.3 | kernel-source | Analysis |
| SUSE Manager Server LTS 4.3 | kernel-default | Analysis |
| SUSE Manager Server LTS 4.3 | kernel-source | Analysis |
| Products past their end of life and not receiving proactive updates anymore. | ||
| SUSE CaaS Platform 4.0 | kernel-source | Analysis |
| SUSE Enterprise Storage 6 | kernel-source | Analysis |
| SUSE Enterprise Storage 7 | kernel-source | Analysis |
| SUSE Enterprise Storage 7.1 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 11 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 12 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 12 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP1-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.0 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.1 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.1 | kernel-rt | Analysis |
| SUSE Linux Enterprise Micro 5.1 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Point of Sale 12 SP2-CLIENT | kernel-source | Analysis |
| SUSE Linux Enterprise Real Time 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Real Time 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Real Time 15 SP3 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Real Time 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Real Time 15 SP4 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Real Time 15 SP5 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Server 11 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 11 SP4 LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 11 SP4 LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 11 SP4-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP2-BCL | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP2-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP2-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 12 SP2-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP4-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP4-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 12 SP4-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP1-BCL | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP1-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP1-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP2-BCL | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP2-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP2-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP3-BCL | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server for Raspberry Pi 12 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 12 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 12 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | kernel-source | Analysis |
| SUSE Manager Proxy 4.0 | kernel-source | Analysis |
| SUSE Manager Proxy 4.1 | kernel-source | Analysis |
| SUSE Manager Proxy 4.2 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server 4.0 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server 4.1 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server 4.2 | kernel-source | Analysis |
| SUSE Manager Server 4.0 | kernel-source | Analysis |
| SUSE Manager Server 4.1 | kernel-source | Analysis |
| SUSE Manager Server 4.2 | kernel-source | Analysis |
| SUSE OpenStack Cloud 7 | kernel-source | Analysis |
| SUSE OpenStack Cloud 9 | kernel-source | Analysis |
| SUSE OpenStack Cloud Crowbar 9 | kernel-source | Analysis |
| SUSE Real Time Module 15 SP3 | kernel-source-rt | Analysis |
| SUSE Real Time Module 15 SP4 | kernel-source-rt | Analysis |
| SUSE Real Time Module 15 SP5 | kernel-source-rt | Analysis |
| openSUSE Leap 15.3 | kernel-source | Analysis |
| openSUSE Leap 15.3 | kernel-source-rt | Analysis |
| openSUSE Leap 15.4 | kernel-source | Analysis |
| openSUSE Leap 15.4 | kernel-source-rt | Analysis |
| openSUSE Leap 15.5 | kernel-source | Analysis |
| openSUSE Leap 15.5 | kernel-source-rt | Analysis |
| Products at an unknown state of their lifecycle. | ||
| SUSE Linux Enterprise Server 15 SP6-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 16.0 | kernel-source | Analysis |
SUSE Timeline for this CVE
CVE page created: Tue Dec 16 16:02:25 2025CVE page last modified: Tue Dec 16 18:53:21 2025