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memorymemory-managementkernel-modulemmap

mmap() Resource temporarily unavailable

I am trying to implement a memory management kernel module. This module uses mmap() system call. After implementation, I tried calling mmap which gives me an error Resource temporarily unavailable I went through this thread. The solution does not work in my case.

Here is the kernel implementation:- Excluding variable declarations. 

kmalloc_ptr = kmalloc(size, GFP_KERNEL)
static int simple_mmap(struct file *filp, struct vm_area_struct *vma)
{
 remap = remap_pfn_range(vma, vma->vm_start, (virt_to_phys)(kmalloc_ptr) >> 12,
                vma->vm_end - vma->vm_start,
                vma->vm_page_prot)
        return -EAGAIN;

value in remap is 0

Solution

  • I found the error, I was not something wrong with the the mapping as I had suspected.

    The error was remap should be used as

    `if ((remap_pfn_range(vma, vma->vm_start, (unsigned long long)(virt_to_phys((void *)mapped_data)) >> PAGE_SHIFT, size, vma->vm_page_prot))
return -EAGAIN`;