VM_INSERT_PFN(9) Memory Management in Linux VM_INSERT_PFN(9)NAME
vm_insert_pfn - insert single pfn into user vma
int vm_insert_pfn(struct vm_area_struct * vma, unsigned long addr, unsigned long pfn);
user vma to map to
target user address of this page
source kernel pfn
Similar to vm_insert_page, this allows drivers to insert individual pages they've allocated into a user vma. Same comments apply.
This function should only be called from a vm_ops->fault handler, and in that case the handler should return NULL.
vma cannot be a COW mapping.
As this is called only for pages that do not currently exist, we do not need to flush old virtual caches or the TLB.
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 VM_INSERT_PFN(9)
Check Out this Related Man Page
__GET_USER_PAGES(9) Memory Management in Linux __GET_USER_PAGES(9)NAME
__get_user_pages - pin user pages in memory
long __get_user_pages(struct task_struct * tsk, struct mm_struct * mm, unsigned long start, unsigned long nr_pages, unsigned int gup_flags,
struct page ** pages, struct vm_area_struct ** vmas, int * nonblocking);
task_struct of target task
mm_struct of target mm
starting user address
number of pages from start to pin
flags modifying pin behaviour
array that receives pointers to the pages pinned. Should be at least nr_pages long. Or NULL, if caller only intends to ensure the pages
are faulted in.
array of pointers to vmas corresponding to each page. Or NULL if the caller does not require them.
whether waiting for disk IO or mmap_sem contention
Returns number of pages pinned. This may be fewer than the number requested. If nr_pages is 0 or negative, returns 0. If no pages were
pinned, returns -errno. Each page returned must be released with a put_page call when it is finished with. vmas will only remain valid
while mmap_sem is held.
Must be called with mmap_sem held for read or write.
__get_user_pages walks a process's page tables and takes a reference to each struct page that each user address corresponds to at a given
instant. That is, it takes the page that would be accessed if a user thread accesses the given user virtual address at that instant.
This does not guarantee that the page exists in the user mappings when __get_user_pages returns, and there may even be a completely
different page there in some cases (eg. if mmapped pagecache has been invalidated and subsequently re faulted). However it does guarantee
that the page won't be freed completely. And mostly callers simply care that the page contains data that was valid *at some point in time*.
Typically, an IO or similar operation cannot guarantee anything stronger anyway because locks can't be held over the syscall boundary.
If gup_flags & FOLL_WRITE == 0, the page must not be written to. If the page is written to, set_page_dirty (or set_page_dirty_lock, as
appropriate) must be called after the page is finished with, and before put_page is called.
If nonblocking != NULL, __get_user_pages will not wait for disk IO or mmap_sem contention, and if waiting is needed to pin all pages,
*nonblocking will be set to 0.
In most cases, get_user_pages or get_user_pages_fast should be used instead of __get_user_pages. __get_user_pages should be used only if
you need some special gup_flags.
COPYRIGHT Kernel Hackers Manual 3.10 June 2014 __GET_USER_PAGES(9)
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