sbrklazy           41 user/user.h    char* sbrklazy(int);
sbrklazy         2597 user/usertests.c   prev_end = sbrklazy(REGION_SZ);
sbrklazy         2626 user/usertests.c   prev_end = sbrklazy(REGION_SZ);
sbrklazy         2642 user/usertests.c       sbrklazy(-1L * REGION_SZ);
sbrklazy         2664 user/usertests.c     sbrklazy(4*PGSIZE);