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rcu: Suppress __mpol_dup() false positive from RCU lockdep

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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>
This commit is contained in:
Paul E. McKenney 2010-03-03 17:50:17 -08:00 committed by Ingo Molnar
parent e6033e3b30
commit 99ee4ca746
1 changed files with 2 additions and 0 deletions
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2
mm/mempolicy.c
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@ -1730,10 +1730,12 @@ struct mempolicy *__mpol_dup(struct mempolicy *old)
if (!new) if (!new)
return ERR_PTR(-ENOMEM); return ERR_PTR(-ENOMEM);
rcu_read_lock();
if (current_cpuset_is_being_rebound()) { if (current_cpuset_is_being_rebound()) {
nodemask_t mems = cpuset_mems_allowed(current); nodemask_t mems = cpuset_mems_allowed(current);
mpol_rebind_policy(old, &mems); mpol_rebind_policy(old, &mems);
} }
rcu_read_unlock();
*new = *old; *new = *old;
atomic_set(&new->refcnt, 1); atomic_set(&new->refcnt, 1);
return new; return new;