CVE-2026-31455 is a high-severity vulnerability in the Linux kernel's XFS filesystem unmount process. The flaw involves the unmount sequence pushing the Active Item List (AIL) while background reclaim and inode garbage collection (inodegc) are still running. This improper ordering can lead to race conditions where inodes are dirtied or freed concurrently, causing potential use-after-free issues and data corruption. The fix reorders the unmount process to stop inodegc and cancel background reclaim before pushing the AIL, preventing these race conditions.