mm: use long type for page counts in mm_populate() and get_user_pages()

Use long type for page counts in mm_populate() so as to avoid integer
overflow when running the following test code:

int main(void) {
  void *p = mmap(NULL, 0x100000000000, PROT_READ,
                 MAP_PRIVATE | MAP_ANON, -1, 0);
  printf("p: %p\n", p);
  mlockall(MCL_CURRENT);
  printf("done\n");
  return 0;
}

Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 25 insertions, 24 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e14a8c7..cdb64e4 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2920,14 +2920,14 @@ follow_huge_pud(struct mm_struct *mm, unsigned long address,
 	return NULL;
 }
 
-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 int flags)
+long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
+			 struct page **pages, struct vm_area_struct **vmas,
+			 unsigned long *position, unsigned long *nr_pages,
+			 long i, unsigned int flags)
 {
 	unsigned long pfn_offset;
 	unsigned long vaddr = *position;
-	int remainder = *length;
+	unsigned long remainder = *nr_pages;
 	struct hstate *h = hstate_vma(vma);
 
 	spin_lock(&mm->page_table_lock);
@@ -2997,7 +2997,7 @@ same_page:
 		}
 	}
 	spin_unlock(&mm->page_table_lock);
-	*length = remainder;
+	*nr_pages = remainder;
 	*position = vaddr;
 
 	return i ? i : -EFAULT;
diff --git a/mm/memory.c b/mm/memory.c
index 7bd22a6..bc929db 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1677,15 +1677,15 @@ static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long add
  * instead of __get_user_pages. __get_user_pages should be used only if
  * you need some special @gup_flags.
  */
-int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
-		     unsigned long start, int nr_pages, unsigned int gup_flags,
-		     struct page **pages, struct vm_area_struct **vmas,
-		     int *nonblocking)
+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)
 {
-	int i;
+	long i;
 	unsigned long vm_flags;
 
-	if (nr_pages <= 0)
+	if (!nr_pages)
 		return 0;
 
 	VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
@@ -1981,9 +1981,9 @@ int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
  *
  * See also get_user_pages_fast, for performance critical applications.
  */
-int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
-		unsigned long start, int nr_pages, int write, int force,
-		struct page **pages, struct vm_area_struct **vmas)
+long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
+		unsigned long start, unsigned long nr_pages, int write,
+		int force, struct page **pages, struct vm_area_struct **vmas)
 {
 	int flags = FOLL_TOUCH;
 
diff --git a/mm/mlock.c b/mm/mlock.c
index 38db3b0..e6638f5 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -160,7 +160,7 @@ long __mlock_vma_pages_range(struct vm_area_struct *vma,
 {
 	struct mm_struct *mm = vma->vm_mm;
 	unsigned long addr = start;
-	int nr_pages = (end - start) / PAGE_SIZE;
+	unsigned long nr_pages = (end - start) / PAGE_SIZE;
 	int gup_flags;
 
 	VM_BUG_ON(start & ~PAGE_MASK);
@@ -382,7 +382,7 @@ int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
 	unsigned long end, nstart, nend;
 	struct vm_area_struct *vma = NULL;
 	int locked = 0;
-	int ret = 0;
+	long ret = 0;
 
 	VM_BUG_ON(start & ~PAGE_MASK);
 	VM_BUG_ON(len != PAGE_ALIGN(len));
diff --git a/mm/nommu.c b/mm/nommu.c
index 87854a5..6ab7066 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -140,10 +140,10 @@ unsigned int kobjsize(const void *objp)
 	return PAGE_SIZE << compound_order(page);
 }
 
-int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
-		     unsigned long start, int nr_pages, unsigned int foll_flags,
-		     struct page **pages, struct vm_area_struct **vmas,
-		     int *retry)
+long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
+		      unsigned long start, unsigned long nr_pages,
+		      unsigned int foll_flags, struct page **pages,
+		      struct vm_area_struct **vmas, int *nonblocking)
 {
 	struct vm_area_struct *vma;
 	unsigned long vm_flags;
@@ -190,9 +190,10 @@ finish_or_fault:
  *   slab page or a secondary page from a compound page
  * - don't permit access to VMAs that don't support it, such as I/O mappings
  */
-int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
-	unsigned long start, int nr_pages, int write, int force,
-	struct page **pages, struct vm_area_struct **vmas)
+long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
+		    unsigned long start, unsigned long nr_pages,
+		    int write, int force, struct page **pages,
+		    struct vm_area_struct **vmas)
 {
 	int flags = 0;