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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2018-05-03 10:35:33 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2018-07-12 15:39:05 -0700
commit1f3e5f51b933cbc25e3da0cdbdac40716df04ddb (patch)
tree5a8524d4be9f45b9848d62bf985b0c43ac894d04 /kernel/rcu
parent1e64b15a4b102e1cd059d4d798b7a78f93341333 (diff)
downloadlinux-1f3e5f51b933cbc25e3da0cdbdac40716df04ddb.tar.bz2
rcu: Add RCU-preempt check for waiting on newly onlined CPU
RCU should only be waiting on CPUs that were online at the time that the current grace period started. Failure to abide by this rule can result in confusing splats during grace-period cleanup and initialization. This commit therefore adds a check to RCU-preempt's preempted-task queuing that checks for waiting on newly onlined CPUs. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu')
-rw-r--r--kernel/rcu/tree_plugin.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 1c9a836af5b6..6b85ce936ad4 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -183,6 +183,9 @@ static void rcu_preempt_ctxt_queue(struct rcu_node *rnp, struct rcu_data *rdp)
raw_lockdep_assert_held_rcu_node(rnp);
WARN_ON_ONCE(rdp->mynode != rnp);
WARN_ON_ONCE(!rcu_is_leaf_node(rnp));
+ /* RCU better not be waiting on newly onlined CPUs! */
+ WARN_ON_ONCE(rnp->qsmaskinitnext & ~rnp->qsmaskinit & rnp->qsmask &
+ rdp->grpmask);
/*
* Decide where to queue the newly blocked task. In theory,