mempolicy: remove tasklist_lock from migrate_pages
Today, tasklist_lock in migrate_pages doesn't protect anything.
rcu_read_lock() provide enough protection from pid hash walk.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 7ee55af..e6d3512 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1310,16 +1310,13 @@
/* 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;