oldbrk           1418 usertests.c      char *a, *b, *c, *lastaddr, *oldbrk, *p, scratch;
oldbrk           1422 usertests.c      oldbrk = sbrk(0);
oldbrk           1490 usertests.c      c = sbrk(-(sbrk(0) - oldbrk));
oldbrk           1543 usertests.c      if(sbrk(0) > oldbrk)
oldbrk           1544 usertests.c        sbrk(-(sbrk(0) - oldbrk));