[Cleanup PATCH] rcu: Do not use rcu_read_lock_held when callingrcu_dereference_check

[Michal Hocko]

Hi Paul,
I guess that this falls down to your area because the code, even though
it touches multiple areas, is RCU specific. Let me know if I should
break it into smaller pieces or that I should push it through other
trees.

git grep -n -A3 "\<rcu_dereference_.*check" doesn't show any other
variants to be "affected".

The patch is based on the current Linus tree (f1bb20a8).
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