Negative current statistic

stat->current is increased by amount of memory requested in user application. During free() it's decreased by size of usable block which is usually larger. Therefore after free() the stat isn't zero but has some negative value.

Start by tracing where stat->current is updated during allocation and free(), comparing the requested memory amount with the usable block size. Reproduce an allocation followed by free() and inspect the resulting statistic. Done means the current statistic reflects the intended accounting without becoming negative.

Written by the indexing model from the issue text.