evict_disabled is used to let other threads know eviction is disabled on a btree. Since it's a shared variable, we should be careful when writing to it or reading it. There are places where it's updated under the evict_walk_lock lock, sometimes we use __wt_atomic_subi32 to decrement its value and in other places, we just read it without any precaution.

It could be a false alarm but I think it deserves attention, especially after the concern raised about prefetch here.