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 e14a8c79a1eb..cdb64e4d238a 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 7bd22a621817..bc929dbad215 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 38db3b094105..e6638f565d42 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 87854a55829d..6ab706608492 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;