Innodb allocates almost 3GB instead if requested 1.5GB

This is a followup of MDEV-11520 .
32bit Windows, with innodb_buffer_pool_size set to 1500M.
however, error log (https://jira.mariadb.org/secure/attachment/42987/error.log) claims that 2.75GB were allocated instead, which is almost double the requested size. This creates memory pressure, resulting into failing allocations later, since only around 1GB virtual memory is left for the whole server(i.e on 64 Windows running 32bit mysqld.exe, because on 32bit Windows, this rounding would result in a server that cannot start