cve 2025 21949

CVE-2025-21949 is a Linux kernel correctness bug affecting LoongArch hugetlb mappings. The vulnerability can produce a kernel BUG during hugetlbfs unmapping when the hugetlb mmap base is not aligned to the PMD (Page Middle Directory) size. This is an availability-first issue, leading to reproducible kernel oopses and host instability. Maintainers have patched the upstream kernel to align hugetlb mmap bases with PMD size to remove the failure condition. This tag covers discussions about the CVE, its impact on LoongArch systems, and the fix applied to address the alignment issue.