Re: [PATCH -next 0/4] blk-cgroup: synchronize del_gendisk() with configuring cgroup policy

[Christoph Hellwig]

On Tue, Dec 20, 2022 at 05:19:12PM +0800, Yu Kuai wrote:
> If we are using a mutex to protect rq_qos ops, it seems the right thing
> to do do also using the mutex to protect blkcg_policy ops, and this
> problem can be fixed because mutex can be held to alloc memroy with
> GFP_KERNEL. What do you think?

Getting rid of the atomic allocations would be awesome.

FYI, I'm also in favor of everything that moves things out of
queue_lock into more dedicated locks.  queue_lock is such an undocument
mess of untargeted things that don't realted to each other right now
that splitting and removing it is becoming more and more important.