Re: [PATCH] pid: remove unnecessary idr_preload()

[Tycho Andersen]

On Tue, Dec 16, 2025 at 10:39:58AM +0100, Oleg Nesterov wrote:
> On 12/15, Tycho Andersen wrote:
> >
> > From: "Tycho Andersen (AMD)" <tycho@xxxxxxxxxx>
> >
> > As near as I can tell, nothing in the second pidmap_lock critical section
> > actually allocates an id, so there is no need to do idr_preload().
> > idr_replace() does not, nor does pidfs_add_pid().
> 
> Yes. The extra idr_preload() was needed for pidfs_add_pid() after the commit
> 9698d5a483654 ("pidfs: rework inode number allocation").
> 
> But please see
> [PATCH v3 2/2] pid: only take pidmap_lock once on alloc
> https://lore.kernel.org/all/20251206131955.780557-3-mjguzik@xxxxxxxxx/

Oh, nice. I was looking at doing this too. I'll head over to that
thread...

Tycho