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MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/8345 An unprivileged local user can mark a huge sparse anonymous mapping (e.g. tens of TiB with only a few pages populated) as MADV_MERGEABLE, which causes ksmd to walk every virtual page address instead of skipping unmapped holes. That pins a CPU for a long time and effectively stalls Kernel Samepage Merging, so it is a local denial-of-service against the system’s page-deduplication path. The fix switches scan_get_next_rmap_item() to walk_page_range() so KSM jumps over holes and only scans mapped pages. The following commit comes from the 6.6 stable tree. CVE: CVE-2025-68211 JIRA: https://redhat.atlassian.net/browse/RHEL-189902 Signed-off-by: Nico Pache <npache@redhat.com> Approved-by: Ricardo Robaina <rrobaina@redhat.com> Approved-by: Luiz Capitulino <luizcap@redhat.com> Approved-by: Rafael Aquini <raquini@redhat.com> Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com> Merged-by: CKI GitLab Kmaint Pipeline Bot <26919896-cki-kmaint-pipeline-bot@users.noreply.gitlab.com>