Kirill Shutemov reported significant percpu memory increase after booting
in 288-cpu VM ([1]) due to commit 41a5db8 ("bpf: Add support for
non-fix-size percpu mem allocation"). The percpu memory is increased
from 111MB to 969MB. The number is from /proc/meminfo.

I tried to reproduce the issue with my local VM which at most supports
upto 255 cpus. With 252 cpus, without the above commit, the percpu memory
immediately after boot is 57MB while with the above commit the percpu
memory is 231MB.

This is not good since so far percpu memory from bpf memory allocator
is not widely used yet. Let us change pre-allocation in init stage
to on-demand allocation when verifier detects there is a need of
percpu memory for bpf program. With this change, percpu memory
consumption after boot can be reduced signicantly.

  [1] https://lore.kernel.org/lkml/20231109154934.4saimljtqx625l3v@box.shutemov.name/

Fixes: 41a5db8 ("bpf: Add support for non-fix-size percpu mem allocation")
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>