Commit 1e50df39 authored Jan 13, 2011 by KOSAKI Motohiro Committed by Linus Torvalds Jan 13, 2011

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>

parent 53a7706d

mm/mempolicy.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -1310,16 +1310,13 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,

		/* 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;