Commit 99ee4ca7 authored Mar 03, 2010 by Paul E. McKenney Committed by Ingo Molnar Mar 04, 2010

rcu: Suppress __mpol_dup() false positive from RCU lockdep



Common code is used during task creation and after the task has
started running.  RCU protection is not needed during task
creation because no other CPU has access to the
under-construction task.  Provide the RCU protection anyway to
suppress the false positive, as there does not appear to be a
good way for the common code to recognize that the task is only
accessible to the CPU creating it.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1267667418-32233-2-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent e6033e3b

mm/mempolicy.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1730,10 +1730,12 @@ struct mempolicy __mpol_dup(struct mempolicy old)

		if (!new)
		return ERR_PTR(-ENOMEM);
		rcu_read_lock();
		if (current_cpuset_is_being_rebound()) {
		nodemask_t mems = cpuset_mems_allowed(current);
		mpol_rebind_policy(old, &mems);
		}
		rcu_read_unlock();
		new = old;
		atomic_set(&new->refcnt, 1);
		return new;

Admin message