Re: [PATCH 1/5] x86/mm/pat: introcude cpa_lock() and cpa_unlock()

From: Peter Zijlstra

Date: Tue Jul 28 2026 - 10:52:29 EST


On Tue, Jul 28, 2026 at 07:30:27AM -0700, Dave Hansen wrote:
> On 7/28/26 07:21, Peter Zijlstra wrote:
> > There was already a patch merged that removed the shole debug_pagealloc
> > exception. Is that not better?
>
> As I'm scanning through email this morning, there's another issue that
> popped up with that patch. It's causing hangs on boot.
>
> It's looking like debug pagealloc not taking the lock is actually
> functional, not an optimization. Although, I hesitate to say
> "functional" and would prefer to use much less nice words to describe it.

Yeah, lets figure out why that is before we retain this wart ;-)