Kernel module linked list strange behaviour - c

Question

I am creating a linked list in kernel module ; It has no problem with adding the first record , in init module i am initializing the map also with create map function ;
typedef struct IP4SYN{
unsigned int KaynakIP;
u_int16_t KaynakPort;
u_int16_t HedefPort;
} IP4SYN;
typedef struct IP4Map{
unsigned int HedefIP;
IP4SYN * a;
size_t s;
size_t n;
} IP4Map;
typedef struct Sessions{
IP4Map * a;
size_t s;
size_t n;
} Sessions;
static size_t blocksize = (1024*102);
Sessions * Session_Map;
static unsigned int get_tsval(void){
return (unsigned int)(ktime_to_ns(ktime_get())>>10);
}
Sessions * CreateMap(size_t initial){
Sessions * pMap = (Sessions *)vmalloc(sizeof(Sessions));
if (initial > 0 && blocksize != initial) {
blocksize = initial;
}
pMap->a = (IP4Map *)vmalloc(sizeof(IP4Map)*blocksize);
memset(pMap->a, 0, sizeof(IP4Map)*blocksize);
pMap->s = blocksize;
pMap->n = 0;
pMap->a->a=(IP4SYN *)vmalloc(sizeof(IP4SYN)*blocksize);
memset(pMap->a->a, 0, sizeof(IP4SYN)*blocksize);
pMap->a->s = blocksize;
pMap->a->n = 0;
return pMap;
}
size_t HedefIPKayitNo(unsigned int HedefIP){
size_t beg = 0;
size_t end = Session_Map->n;
for (beg; beg < end; beg) {
IP4Map map = Session_Map->a[beg];
if(map.HedefIP==HedefIP){
return beg;
break;
}
}
return beg;
}
size_t YeniHedefIP(unsigned int HedefIP,size_t index){
Session_Map->a[index].HedefIP = HedefIP;
Session_Map->n++;
}
I want to check if ip exist in listed and if not listed i want to add it to the list. But strangely it causing lack of kernel on 2nd try . 1st add-up is working perfect. what should be the issue ?
size_t IP_Index = HedefIPKayitNo(hedef_ip);
if(IP_Index == Session_Map->n ){
YeniHedefIP(hedef_ip,(IP_Index));
}