Hello,

On Thu, 2 May 2013, Julian Anastasov wrote:

	Note that I'm testing on some 9-year old
UP system, i.e. 1 CPU. Now I enabled SMP to test CONFIG_TREE_RCU
and the results are same. I think, it should be just like
the TINY_RCU in terms of these debuggings (non-preempt). Extra 
rcu_read_lock gives me "Illegal context switch in RCU read-side
critical section" in addition to the "BUG: sleeping function
called from invalid context" message.

	Just to clarify about the test with extra
rcu_read_lock because above paragraph is very confusing:

- The __might_sleep call with PREEMPT_ACTIVE | PREEMPT_RCU_OFFSET
just warns with "BUG: sleeping function called from invalid context"
because its rcu_sleep_check is silenced. We match the
nesting depth only.

- but __cond_resched -> __schedule -> schedule_debug warns about
the extra rcu_read_lock() with "BUG: scheduling while atomic" and
then with "Illegal context switch in RCU read-side critical section"
from rcu_sleep_check(0).

Regards

--
Julian Anastasov [off-list ref]