https://man7.org/linux/man-pages/man5/proc.5.html says the following: VmallocUsed %lu Amount of vmalloc area which is used. Since Linux 4.4, this field is no longer calculated, and is hard coded as 0. See /proc/vmallocinfo. However, this was changed in 5.3 in https://github.com/torvalds/linux/commit/97105f0ab7b877a8ece2005e214894e93793950c.
Could you please send a patch according to the ./CONTRIBUTING file in the repo?