On 12/21/18 7:54 AM, Dennis Zhou wrote:

I cleaned up blkg_tryget_closest() to require rcu_read_lock() earlier.
However, this was a subtle case too which clearly was too subtle for me.
The idea was the src bio should be holding a ref to the blkg so rcu
wasn't technically needed. If it doesn't hold a ref, it should be %NULL
and the blkg->parent pointers are unused.

This adds the appropriate read lock in bio_clone_blkg_association().

Shall I just fold this with the previous? I staged it in a
later-in-merge-cycle branch, so that's not an issue to amend.

-- 
Jens Axboe