On Fri, 2019-03-15 at 16:57 +0800, Jianchao Wang wrote:

[2] https://marc.info/?l=linux-block&m=154526189023236&w=2

Hi Jianchao,

That is a reference to the "BUG: KASAN: use-after-free in bt_iter" issue.
I think that issue can be fixed in another way than modifying all code that
iterates over tags, namely by adding an rcu_read_lock() / rcu_read_unlock()
pair in bt_for_each() and bt_tags_for_each() and by changing the calls in
blk_mq_free_rqs() and blk_free_flush_queue() that free the data structures
used by the tag iteration functions into kfree_rcu() or call_rcu() calls.

Thanks,

Bart.