Compilation time increase with this commit when enabling DEBUG_INFO

[Leyfoon Tan]

After the commit "fork: lock VMAs of the parent process when forking" in [1], the compilation time increases from ~2 minutes to 8.5 minutes when enabling CONFIG_DEBUG_INFO* (CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT/CONFIG_DEBUG_INFO_DWARF4/CONFIG_DEBUG_INFO_DWARF5).
Looking at the commit changes, not sure why it causes the increase in compilation time. Any ideas?

From:

# time make -j
real    1m51.522s
user    59m55.836s
sys     5m29.177s

Increase to:

# time make -j
real    8m31.967s
user    69m24.410s
sys     5m54.588s

Note, compile time above with ARCH=riscv, defconfig + CONFIG_DEBUG_INFO_DWARF4.

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2b4f3b4987b56365b981f44a7e843efa5b6619b9