Re: [PATCH v8 07/11] proc: flush task dcache entries from all procfs instances

[Al Viro]

On Wed, Feb 12, 2020 at 12:35:04PM -0800, Linus Torvalds wrote:
> On Wed, Feb 12, 2020 at 12:03 PM Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
> >
> > What's to prevent racing with fs shutdown while you are doing the second part?
> 
> I was thinking that only the proc_flush_task() code would do this.
> 
> And that holds a ref to the vfsmount through upid->ns.
> 
> So I wasn't suggesting doing this in general - just splitting up the
> implementation of d_invalidate() so that proc_flush_task_mnt() could
> delay the complex part to after having traversed the RCU-protected
> list.
> 
> But hey - I missed this part of the problem originally, so maybe I'm
> just missing something else this time. Wouldn't be the first time.

Wait, I thought the whole point of that had been to allow multiple
procfs instances for the same userns?  Confused...