Re: [PATCH v3] block: flush all throttled bios when deleting the cgroup

[Tejun Heo]

Hello,

On Sat, Aug 17, 2024 at 03:11:08PM +0800, Li Lingfeng wrote:
> From: Li Lingfeng <lilingfeng3@xxxxxxxxxx>
> 
> When a process migrates to another cgroup and the original cgroup is deleted,
> the restrictions of throttled bios cannot be removed. If the restrictions
> are set too low, it will take a long time to complete these bios.
> 
> Refer to the process of deleting a disk to remove the restrictions and
> issue bios when deleting the cgroup.
> 
> This makes difference on the behavior of throttled bios:
> Before: the limit of the throttled bios can't be changed and the bios will
> complete under this limit;
> Now: the limit will be canceled and the throttled bios will be flushed
> immediately.

I still don't see why this behavior is better. Wouldn't this make it easy to
escape IO limits by creating cgroups, doing a bunch of IOs and then deleting
them?

Thanks.

-- 
tejun