Re: [PATCH v2] block: flush all throttled bios when deleting the cgroup

[Michal Koutný]

On Fri, Jun 28, 2024 at 10:04:20AM GMT, Li Lingfeng <lilingfeng@xxxxxxxxxxxxxxx> wrote:
> I think it may be more appropriate to remove the limit of bios after the
> cgroup is deleted, rather than let the bios continue to be throttled by a
> non-existent cgroup.

I'm not that familiar with this part -- can this also happen for IOs
submitted by an exited task? (In contrast to a running task migrated
elsewhere.)

> If the limit is set too low, and the original cgourp has been deleted, we
> now have no way to make the bios complete immediately, but to wait for the
> bios to slowly complete under the limit.

It makes some sense, it's not unlike reparenting of memcg objects, IIRC
flushed bios would actually be passed to a parent throtl_grp, right?

Thanks,
Michal

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