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Commit a145dd41 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

VM: add "vm_insert_page()" function 



This is what a lot of drivers will actually want to use to insert
individual pages into a user VMA.  It doesn't have the old PageReserved
restrictions of remap_pfn_range(), and it doesn't complain about partial
remappings.

The page you insert needs to be a nice clean kernel allocation, so you
can't insert arbitrary page mappings with this, but that's not what
people want.

Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent f8e98843

include/linux/mm.h

+1 −0
Original line number Diff line number Diff line
@@ -956,6 +956,7 @@ struct page *vmalloc_to_page(void *addr); 
unsigned long vmalloc_to_pfn(void *addr);

int remap_pfn_range(struct vm_area_struct *, unsigned long addr,

			unsigned long pfn, unsigned long size, pgprot_t);

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



struct page *follow_page(struct vm_area_struct *, unsigned long address,

			unsigned int foll_flags);

mm/memory.c

+34 −2
Original line number Diff line number Diff line
@@ -1172,7 +1172,7 @@ static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *pa 
	spinlock_t *ptl;  



	retval = -EINVAL;

	if (PageAnon(page) || !PageReserved(page))

	if (PageAnon(page))

		goto out;

	retval = -ENOMEM;

	flush_dcache_page(page);
@@ -1196,6 +1196,35 @@ out: 
	return retval;

}



/*

 * This allows drivers to insert individual pages they've 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

 * (which is mainly an issue of doing "set_page_count(page, 1)" for

 * each sub-page, and then freeing them one by one when you free

 * them rather than freeing it as a compound page).

 *

 * NOTE! Traditionally this was done with "remap_pfn_range()" which

 * took an arbitrary page protection parameter. This doesn't allow

 * that. Your vma protection will have to be set up correctly, which

 * means that if you want a shared writable mapping, you'd better

 * ask for a shared writable mapping!

 *

 * The page does not need to be reserved.

 */

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

{

	if (addr < vma->vm_start || addr >= vma->vm_end)

		return -EFAULT;

	if (!page_count(page))

		return -EINVAL;

	return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);

}

EXPORT_SYMBOL_GPL(vm_insert_page);



/*

 * Somebody does a pfn remapping that doesn't actually work as a vma.

 *
@@ -1225,8 +1254,11 @@ static int incomplete_pfn_remap(struct vm_area_struct *vma, 
	if (!pfn_valid(pfn))

		return -EINVAL;



	retval = 0;

	page = pfn_to_page(pfn);

	if (!PageReserved(page))

		return -EINVAL;



	retval = 0;

	while (start < end) {

		retval = insert_page(vma->vm_mm, start, page, prot);

		if (retval < 0)