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Commit 55cfaa3c authored by Zeng Zhaoming's avatar Zeng Zhaoming Committed by Linus Torvalds
Browse files

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: default avatarZeng Zhaoming <zengzm.kernel@gmail.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1f64d69c

mm/mempolicy.c

+3 −0
Original line number Original line Diff line number Diff line
@@ -1307,15 +1307,18 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode, 
		goto out;

		goto out;





	/* Find the mm_struct */

	/* Find the mm_struct */

	rcu_read_lock();

	read_lock(&tasklist_lock);

	read_lock(&tasklist_lock);

	task = pid ? find_task_by_vpid(pid) : current;

	task = pid ? find_task_by_vpid(pid) : current;

	if (!task) {

	if (!task) {

		read_unlock(&tasklist_lock);

		read_unlock(&tasklist_lock);

		rcu_read_unlock();

		err = -ESRCH;

		err = -ESRCH;

		goto out;

		goto out;

	}

	}

	mm = get_task_mm(task);

	mm = get_task_mm(task);

	read_unlock(&tasklist_lock);

	read_unlock(&tasklist_lock);

	rcu_read_unlock();





	err = -EINVAL;

	err = -EINVAL;

	if (!mm)

	if (!mm)