get_user_pages failed for PCIe memory

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http://stackoverflow.com – I have mapped the pci memory in user space like fs = open("/dev/mem",O_RDWR | O_SYNC); mmap_src = mmap(NULL, BUFF_COUNT, PROT_READ | PROT_WRITE, MAP_SHARED, fs, 0xe0000000); 0xe0000000 is the addressof pci memory device. After mmaped get succeeded, I pass that address to driver using ioctl function. In driver code, I call get_user_pages from that address which i got from ioctl. In execution, get_user_pages call fails. Any idea to how to resolve this. (HowTos)