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hugetlb: follow_hugetlb_page() for write access

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When calling get_user_pages(), a write flag is passed in by the caller to
indicate if write access is required on the faulted-in pages.  Currently,
follow_hugetlb_page() ignores this flag and always faults pages for
read-only access.  This can cause data corruption because a device driver
that calls get_user_pages() with write set will not expect COW faults to
occur on the returned pages.

This patch passes the write flag down to follow_hugetlb_page() and makes
sure hugetlb_fault() is called with the right write_access parameter.

[[email protected]: build fix]
Signed-off-by: Adam Litke <[email protected]>
Reviewed-by: Ken Chen <[email protected]>
Cc: David Gibson <[email protected]>
Cc: William Lee Irwin III <[email protected]>
Cc: Badari Pulavarty <[email protected]>
Signed-off-by: Erez Zadok <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Adam Litke 2007-11-14 16:59:33 -08:00 • committed by Linus Torvalds
commit 5b23dbe817
3 changed files with 6 additions and 5 deletions
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5
mm/hugetlb.c
View file

@ -868,7 +868,8 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
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)
unsigned long *position, int *length, int i,
int write)
{
unsigned long pfn_offset;
unsigned long vaddr = *position;
@ -890,7 +891,7 @@ int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
int ret;
spin_unlock(&mm->page_table_lock);
ret = hugetlb_fault(mm, vma, vaddr, 0);
ret = hugetlb_fault(mm, vma, vaddr, write);
spin_lock(&mm->page_table_lock);
if (!(ret & VM_FAULT_ERROR))
continue;

2
mm/memory.c
View file

@ -1036,7 +1036,7 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
if (is_vm_hugetlb_page(vma)) {
i = follow_hugetlb_page(mm, vma, pages, vmas,
&start, &len, i);
&start, &len, i, write);
continue;
}