Re: [PATCH v3] mm/migrate_device: Clear stale mapping after freeing swapcache

[Andrew Morton]

On Mon, 27 Jul 2026 16:28:42 +0530 "Yadav, Arvind" <arvind.yadav@xxxxxxxxx> wrote:

> >> --- a/mm/migrate_device.c
> >> +++ b/mm/migrate_device.c
> >> @@ -1182,6 +1182,11 @@ static void __migrate_device_pages(unsigned long *src_pfns,
> >>   							 MIGRATE_PFN_COMPOUND);
> >>   					goto next;
> >>   				}
> >> +				/*
> >> +				 * reset nr so that only first after-split folio
> >> +				 * is processed below
> >> +				 */
> >> +				nr = 1;
> > We should also add a VM_WARN_ON_ONCE(folio_test_swapcache(folio))
> 
> 
> Agreed , but folio_test_swapcache()  is not valid immediately after the 
> split, as the order-0 folios may still be in swapcache.
> I’ll use just before nr = 1

AI review suggest there might be another bug in here:
	https://sashiko.dev/#/patchset/20260727053920.3494211-1-arvind.yadav@xxxxxxxxx