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Commit 86e5216f authored by Adam Litke's avatar Adam Litke Committed by Linus Torvalds
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[PATCH] Hugetlb: Reorganize hugetlb_fault to prepare for COW 



This patch splits the "no_page()" type activity into its own function,
hugetlb_no_page().  hugetlb_fault() becomes the entry point for hugetlb faults
and delegates to the appropriate handler depending on the type of fault.
Right now we still have only hugetlb_no_page() but a later patch introduces a
COW fault.

Signed-off-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: default avatarAdam Litke <agl@us.ibm.com>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: "Seth, Rohit" <rohit.seth@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 85ef47f7

mm/hugetlb.c

+25 −9
Original line number Diff line number Diff line
@@ -376,20 +376,15 @@ static struct page *find_or_alloc_huge_page(struct address_space *mapping, 
	return page;

}



int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,

			unsigned long address, int write_access)

int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,

			unsigned long address, pte_t *ptep)

{

	int ret = VM_FAULT_SIGBUS;

	unsigned long idx;

	unsigned long size;

	pte_t *pte;

	struct page *page;

	struct address_space *mapping;



	pte = huge_pte_alloc(mm, address);

	if (!pte)

		goto out;



	mapping = vma->vm_file->f_mapping;

	idx = ((address - vma->vm_start) >> HPAGE_SHIFT)

		+ (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
@@ -408,11 +403,11 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
		goto backout;



	ret = VM_FAULT_MINOR;

	if (!pte_none(*pte))

	if (!pte_none(*ptep))

		goto backout;



	add_mm_counter(mm, file_rss, HPAGE_SIZE / PAGE_SIZE);

	set_huge_pte_at(mm, address, pte, make_huge_pte(vma, page));

	set_huge_pte_at(mm, address, ptep, make_huge_pte(vma, page));

	spin_unlock(&mm->page_table_lock);

	unlock_page(page);

out:
@@ -426,6 +421,27 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
	goto out;

}



int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,

			unsigned long address, int write_access)

{

	pte_t *ptep;

	pte_t entry;



	ptep = huge_pte_alloc(mm, address);

	if (!ptep)

		return VM_FAULT_OOM;



	entry = *ptep;

	if (pte_none(entry))

		return hugetlb_no_page(mm, vma, address, ptep);



	/*

	 * We could get here if another thread instantiated the pte

	 * before the test above.

	 */

	return VM_FAULT_MINOR;

}



int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,

			struct page **pages, struct vm_area_struct **vmas,

			unsigned long *position, int *length, int i)