|VM_MAP_RAM(9)||Memory Management in Linux||VM_MAP_RAM(9)|
vm_map_ram - map pages linearly into kernel virtual address (vmalloc space)
void * vm_map_ram(struct page ** pages, unsigned int count, int node, pgprot_t prot);
If you use this function for less than VMAP_MAX_ALLOC pages, it could be faster than vmap so it's good. But if you mix long-life and short-life objects with vm_map_ram, it could consume lots of address space through fragmentation (especially on a 32bit machine). You could see failures in the end. Please use this function for short-lived objects.
a pointer to the address that has been mapped, or NULL on failure
|January 2017||Kernel Hackers Manual 4.8.|