From 5b23dbe8173c212d6a326e35347b038705603d39 Mon Sep 17 00:00:00 2001 From: Adam Litke Date: Wed, 14 Nov 2007 16:59:33 -0800 Subject: hugetlb: follow_hugetlb_page() for write access 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. [ezk@cs.sunysb.edu: build fix] Signed-off-by: Adam Litke Reviewed-by: Ken Chen Cc: David Gibson Cc: William Lee Irwin III Cc: Badari Pulavarty Signed-off-by: Erez Zadok Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 5 +++-- mm/memory.c | 2 +- 2 files changed, 4 insertions(+), 3 deletions(-) (limited to 'mm') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 8b809ecefa39..e2c80631d36a 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -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; diff --git a/mm/memory.c b/mm/memory.c index 9791e4786843..7b0403bfc97f 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -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; } -- cgit v1.2.3-59-g8ed1b