why am i running out of heap memory when i am freeing my linked list?

[luke]

i am creating a user interface using the sh1106 driver for a 128x64 pixel oled screen. so every screen is a list of items to be scrolled; however almost every screen i am using a linked list for the list of elements. in one screen i am creating a linked list and freeing it for about 12 to 15 times but when i reach a number like that the malloc is returning NULL so that means the malloc is not able to find the memory space i need. but what could be the cause? could it be a memory leak from the way i am freeing the linked list? could it be that the memory free space has become too fragmented? if so why only this linked list is messing up?

thanks in advance for ur help guys! and if there is anything needs clearing up or u need some extra info let me now and ill post it.

the code is below: (please keep in mind that i am extracting information from database saved in flash)

void createNotesListFromDb(linkedListNotes_t **head){

notes_t notesStructure;
uint8_t tuningID = dbGetTuningID(instrumentRefID);
tuningRefID = tuningID;
tuningNotesCount = dbGetTuningNotesCount(tuningID);
nbrOfNoteNodes = 0;
char notesTransferArray[4];


for(uint8_t nmbr = 1;nmbr <= tuningNotesCount; nmbr++)
{
	notesStructure = dbGetNote(tuningID, nmbr);
	
	// the next part is to fill a new node with desired values and information
	linkedListNotes_t * newNoteNode;
	newNoteNode = (linkedListNotes_t*)malloc(sizeof(linkedListNotes_t));
	newNoteNode->index = notesStructure.index;
	newNoteNode->alteration = notesStructure.alteration;
	newNoteNode->octave = notesStructure.octave;
	newNoteNode->cents = notesStructure.cents;
	generateNoteName(notesTransferArray, notesStructure.index, notesStructure.alteration, notesStructure.octave);
	newNoteNode->name = (char*)malloc(strlen(notesTransferArray)+1);
	strcpy(newNoteNode->name, notesTransferArray);
	newNoteNode->next = NULL;
	
	*head = addNotesNodeToTail(*head, newNoteNode);
	
	nbrOfNoteNodes++;
}

}

void freeNotesList(linkedListNotes_t * head){

linkedListNotes_t * tmp = NULL;

while (head != NULL)
{
	tmp = head;
	head = head->next;
	tmp->next = NULL;
	free(tmp->name);
	tmp->name = NULL;
	free(tmp);
	tmp=NULL;
}

}

linkedListNotes_t * addNotesNodeToTail(linkedListNotes_t *head, linkedListNotes_t * newNode){

linkedListNotes_t * temp;

if (!head)
{
    head = newNode;
    return head;
}

temp = head;

while (temp->next)
	{
    temp = temp->next;
	}

temp->next = newNode;

return head;

}

[endnode]

There are many people who think malloc (and also C++ in general) should be banned from embedded programming;) Discussion about latter could become long and rather philosophical but for the first one there are several reasons and quite wide consensus. E.g. one of first google search hits here.

[luke]

after this experience, i dont recommend using malloc for embedded systems hoping that a mcu manufacturer built a library to replace the general malloc and have better memory management like nrf_malloc from mem_manager.c and sdk_config.h ... also helps tract the nrf_mallocs, nrf_frees.. on a serial com port.