SBRK_ERROR         55 user/umalloc.c   if(p == SBRK_ERROR)
SBRK_ERROR        253 user/usertests.c   if(a == (uint64) SBRK_ERROR) {
SBRK_ERROR        258 user/usertests.c   if (sbrk(-8192) == SBRK_ERROR) {
SBRK_ERROR       2014 user/usertests.c     if(a == (char*)SBRK_ERROR){
SBRK_ERROR       2087 user/usertests.c   if(c == (char*)SBRK_ERROR){
SBRK_ERROR       2188 user/usertests.c       if (sbrk(BIG - (uint64)sbrk(0)) ==  (char*)SBRK_ERROR)
SBRK_ERROR       2214 user/usertests.c   if(c == (char*)SBRK_ERROR){
SBRK_ERROR       2228 user/usertests.c     if(a == (char*)SBRK_ERROR){
SBRK_ERROR       2598 user/usertests.c   if (prev_end == (char *) SBRK_ERROR) {
SBRK_ERROR       2627 user/usertests.c   if (prev_end == (char*)SBRK_ERROR) {
SBRK_ERROR       2922 user/usertests.c         if(a == SBRK_ERROR)
SBRK_ERROR       3122 user/usertests.c     if(a == SBRK_ERROR){