On Thu, May 25, 2023 at 11:25:05AM -0400, Waiman Long <longman@redhat.com> wrote:
> Since the percpu blkg_iostat_set's that are linked in the lockless list will
> be freed if the corresponding blkcg_gq is freed, we need to flush the
> lockless list to avoid potential use-after-free in a future
> cgroup_rstat_flush*() call.

Ah, so that was meant to the situation post-patch (that removes refcnt
of entries on list lockless).

(It sounded like an answer to Yosry's question about
cgroup_rstat_flush in offline_css in pre-patch version. Nevermind, this
would need other adjustments.)

Thanks,
Michal