The “vmap area” is a range of kernel address space used when the kernel
needs to virtually map a range of memory; among other things, memory
allocations obtained from vmalloc() and loadable modules are
placed there. At the 2023 Linux Storage,
Filesystem, Memory-Management and BPF Summit, Uladzislau Rezki,
presenting remotely,
explained a performance problem related to the vmap area and discussed
possible solutions.

Source: LWN.net – [$] Mitigating vmap lock contention