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

[Al Viro]

On Wed, Feb 12, 2020 at 08:38:33PM +0000, Al Viro wrote:
> 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...

s/userns/pidns/, sorry