HWPOISON: Use get_user_page_fast in hwpoison madvise

The previous version didn't take the mmap_sem before calling gup(), which is racy. Use get_user_pages_fast() instead which doesn't need any locks. This is also faster of course, but then it doesn't really matter because this is just a testing path. Based on report from Nick Piggin. Cc: [email protected] Signed-off-by: Andi Kleen <[email protected]>
akeromi · Dec 16, 2009 · d15f107 · d15f107
1 parent 1bfe5fe
commit d15f107
Showing 1 changed file with 1 addition and 2 deletions.
diff --git a/mm/madvise.c b/mm/madvise.c
@@ -230,8 +230,7 @@ static int madvise_hwpoison(unsigned long start, unsigned long end)
 		return -EPERM;
 	for (; start < end; start += PAGE_SIZE) {
 		struct page *p;
-		int ret = get_user_pages(current, current->mm, start, 1,
-						0, 0, &p, NULL);
+		int ret = get_user_pages_fast(start, 1, 0, &p);
 		if (ret != 1)
 			return ret;
 		printk(KERN_INFO "Injecting memory failure for page %lx at %lx\n",