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-rw-r--r--mm/gup.c17
1 files changed, 7 insertions, 10 deletions
diff --git a/mm/gup.c b/mm/gup.c
index fc704dc37914..84891c06d485 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -2123,13 +2123,9 @@ static void gup_pgd_range(unsigned long addr, unsigned long end,
* Check if it's allowed to use __get_user_pages_fast() for the range, or
* we need to fall back to the slow version:
*/
-bool gup_fast_permitted(unsigned long start, int nr_pages)
+static bool gup_fast_permitted(unsigned long start, unsigned long end)
{
- unsigned long len, end;
-
- len = (unsigned long) nr_pages << PAGE_SHIFT;
- end = start + len;
- return end >= start;
+ return true;
}
#endif
@@ -2150,6 +2146,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
len = (unsigned long) nr_pages << PAGE_SHIFT;
end = start + len;
+ if (end <= start)
+ return 0;
if (unlikely(!access_ok((void __user *)start, len)))
return 0;
@@ -2165,7 +2163,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
* block IPIs that come from THPs splitting.
*/
- if (gup_fast_permitted(start, nr_pages)) {
+ if (gup_fast_permitted(start, end)) {
local_irq_save(flags);
gup_pgd_range(start, end, write ? FOLL_WRITE : 0, pages, &nr);
local_irq_restore(flags);
@@ -2224,13 +2222,12 @@ int get_user_pages_fast(unsigned long start, int nr_pages,
len = (unsigned long) nr_pages << PAGE_SHIFT;
end = start + len;
- if (nr_pages <= 0)
+ if (end <= start)
return 0;
-
if (unlikely(!access_ok((void __user *)start, len)))
return -EFAULT;
- if (gup_fast_permitted(start, nr_pages)) {
+ if (gup_fast_permitted(start, end)) {
local_irq_disable();
gup_pgd_range(addr, end, gup_flags, pages, &nr);
local_irq_enable();