mm/mempolicy.c: add rcu read lock to protect pid structure

find_task_by_vpid() should be protected by rcu_read_lock(), to prevent free_pid() reclaiming pid. Signed-off-by: Zeng Zhaoming <[email protected]> Cc: "Paul E. McKenney" <[email protected]> Cc: KOSAKI Motohiro <[email protected]> Cc: Christoph Lameter <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
laijs · Dec 2, 2010 · 55cfaa3 · 55cfaa3
1 parent 1f64d69
commit 55cfaa3
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
@@ -1307,15 +1307,18 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
 		goto out;
 
 	/* Find the mm_struct */
+	rcu_read_lock();
 	read_lock(&tasklist_lock);
 	task = pid ? find_task_by_vpid(pid) : current;
 	if (!task) {
 		read_unlock(&tasklist_lock);
+		rcu_read_unlock();
 		err = -ESRCH;
 		goto out;
 	}
 	mm = get_task_mm(task);
 	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 
 	err = -EINVAL;
 	if (!mm)