I'm writing a device driver for a memory-mapped device on x86-64. I'm mapping the device in the kernel using ioremap_cache(). My file_operations.mmap function is as follows: static int dev_mmap(struct file *filep, struct vm_area_struct *vma) { vma->vm_page_prot.pgprot|=_PAGE_BIT_RW; return vm_iomap_memory(vma,START,LEN); } The user process calls mmap(..,PROT_READ|PROT_WRITE|PROT_EXEC,..). The mapping in /proc/[pid]/maps shows the write bit. However, when looking at the actual page table entry does not have the RW bit set. For example: virtual address = 0000_0001_8000_0000 cr3 = 0000_0000_700a_e000 phys:0000_0000_700a_e000 = 0000_0000_7e05_5067 (P|RW|US|A|D) phys:0000_0000_7e05_5030 = 0000_0001_66e2_9067 (P|RW|US|A|D) phys:0000_0001_66e2_9000 = 0000_0001_69db_3067 (P|RW|US|A|D) phys:0000_0001_69db_3000 = 0000_0000_8020_0225 (P|US|A|SOFTW1) Am I doing something wrong? Jethro