Re: [PATCH v2] mm/page_vma_mapped_walk: Use ptep_get_lockless() for lockless access

[Alexander Gordeev]

On Thu, May 07, 2026 at 09:34:33AM +0000, Wei Yang wrote:
> >@@ -310,7 +310,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
> > 				goto restart;
> > 			}
> > 			pvmw->pte++;
> >-		} while (pte_none(ptep_get(pvmw->pte)));
> >+		} while (pte_none(ptep_get_lockless(pvmw->pte)));
> 
> As Oscar mentioned in lkml.org/lkml/2026/4/27/630, map_pte() may take the
> lock. So probably it is not right?

If I read the code correctly map_pte() might take the lock, but also
might not take it. If it took the lock and uses ptep_get_lockless(),
then it is fine. But if it did not take the lock and uses ptep_get(),
then it is an issue.

> > 
> > 		if (!pvmw->ptl) {
> > 			spin_lock(ptl);
> >-- 
> >2.51.0
> >
> 
> -- 
> Wei Yang

Thanks!