Missing return of memory allocation API

Hi, I am trying to develop a memory usage monitoring tool using ebpf. The API I am targeting at are malloc family and mmap.

To do so, I am trying to monitor the the enter of the apis and the exit of the apis using uprobes.

During my experiment, I found some very interesting thing. Firstly, it seems that all the enter events can be captured however, in some cases, their corresponding exit events are missing. Secondly, theoretically, any enter event should follow an exit event right away. However, I did notice that two enter event follows two corresponding exit event.

Is there any method to revolve it ?

Best Regards,
Johnny