CVE-2026-31654 mm/vma: fix memory leak in __mmap_region()

In the Linux kernel, the following vulnerability has been resolved: mm/vma: fix memory leak in mmapregion commit 605f6586ecf7 "mm/vma: do not leak memory when .mmapprepare swaps the file" handled the success path by skipping getfile via filedoesntneedget, but missed the error path. When /dev/zero...