On 9/18/20 12:37 PM, Christoph Hellwig wrote:

+static int gnttab_apply(pte_t *pte, unsigned long addr, void *data) +{

• pte_t ***p = data;
• **p = pte;
• (*p)++;
• return 0;

+}

static int arch_gnttab_valloc(struct gnttab_vm_area *area, unsigned nr_frames) { area->ptes = kmalloc_array(nr_frames, sizeof(*area->ptes), GFP_KERNEL); if (area->ptes == NULL) return -ENOMEM;

• area->area = alloc_vm_area(PAGE_SIZE * nr_frames, area->ptes);
• if (area->area == NULL) {

• kfree(area->ptes);
  

• return -ENOMEM;
  

• }

• area->area = get_vm_area(PAGE_SIZE * nr_frames, VM_IOREMAP);
• if (!area->area)

• goto out_free_ptes;
  

• if (apply_to_page_range(&init_mm, (unsigned long)area->area->addr,

• 	PAGE_SIZE * nr_frames, gnttab_apply, &area->ptes))
  

This will end up incrementing area->ptes pointer. So perhaps something like

pte_t **ptes = area->ptes;

if (apply_to_page_range(&init_mm, (unsigned long)area->area->addr,                         PAGE_SIZE * nr_frames, gnttab_apply, &ptes)) {

...

}

-boris