Messages in this thread Patch in this message | | | From | "Paul E. McKenney" <> | Subject | [PATCH tip/core/rcu 2/3] rcu: suppress __mpol_dup() false positive from RCU lockdep | Date | Wed, 3 Mar 2010 17:50:17 -0800 |
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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.
Cc: Paul Menage <menage@google.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> --- mm/mempolicy.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 290fb5b..3cec080 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -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; -- 1.6.6
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