[PATCH] mm/migrate: Avoid possible unnecessary ptrace_may_access() call in kernel_move_pages()

[Miaohe Lin]

There is no need to check if this process has the right to modify the
specified process when they are same.

Signed-off-by: Hongxiang Lou <louhongxiang@xxxxxxxxxx>
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
 mm/migrate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 34a842a8eb6a..342c1ce0b433 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1903,7 +1903,7 @@ static int kernel_move_pages(pid_t pid, unsigned long nr_pages,
 	 * Check if this process has the right to modify the specified
 	 * process. Use the regular "ptrace_may_access()" checks.
 	 */
-	if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
+	if (pid && !ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
 		rcu_read_unlock();
 		err = -EPERM;
 		goto out;
-- 
2.19.1