Man page 9 : vm_insert_page

vm_insert_page - insert single page into user vma

int vm_insert_page(struct vm_area_struct *  vma , unsigned long  addr , struct page *  page );

vma
    user vma to map to

addr
    target user address of this page

page
    source kernel page

This allows drivers to insert individual pages theyAqve allocated into a user vma.

The page has to be a nice clean _individual_ kernel allocation. If you allocate a compound page, you need to have marked it as such (__GFP_COMP), or manually just split the page up yourself (see split_page).

NOTE! Traditionally this was done with « remap_pfn_range » which took an arbitrary page protection parameter. This doesnAqt allow that. Your vma protection will have to be set up correctly, which means that if you want a shared writable mapping, youAqd better ask for a shared writable mapping!

The page does not need to be reserved.

Usually this function is called from f_op->mmap handler under mm->mmap_sem write-lock, so it can change vma->vm_flags. Caller must set VM_MIXEDMAP on vma if it wants to call this function from other places, for example from page-fault handler.