tree aa11d64d780bba090f5e964308ab88c397340754
parent 570dd3c7424179b831decb655ea9dd1ecea38adc
author Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1462215536 -0700
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1466030700 -0700

rcu: Make call_rcu_tasks() tolerate first call with irqs disabled

Currently, if the very first call to call_rcu_tasks() has irqs disabled,
it will create the rcu_tasks_kthread with irqs disabled, which will
result in a splat in the memory allocator, which kthread_run() invokes
with the expectation that irqs are enabled.

This commit fixes this problem by deferring kthread creation if called
with irqs disabled.  The first call to call_rcu_tasks() that has irqs
enabled will create the kthread.

This bug was detected by rcutorture changes that were motivated by
Iftekhar Ahmed's mutation-testing efforts.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>