This is the Question 3 of the Webinar:

Q: In the memmgr message handler, what the purpose of 
proc_wlock_adp(prp);

A: This function call is used to acquire a write lock to process memory (aspace), the process  defined by the 'prp' 
argument. 

Definition of the function can be found in:
file: \svn\trunk\services\system\memmgr\memmgr_support.c 
line 82 
int rdecl
proc_wlock_adp(PROCESS *prp) {
...
}

Regards, 
-Vlad