Hello Mathew,
> -----Original Message-----
> From: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> Sent: Tuesday, March 5, 2024 11:19 PM
> To: Borah, Chaitanya Kumar <chaitanya.kumar.borah@xxxxxxxxx>
> Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Kurmi, Suresh Kumar
> <suresh.kumar.kurmi@xxxxxxxxx>; Saarinen, Jani <jani.saarinen@xxxxxxxxx>
> Subject: Re: Regression on linux-next (next-20240228)
>
> On Tue, Mar 05, 2024 at 06:49:16AM +0000, Borah, Chaitanya Kumar wrote:
> > Issue is still seen with the following changes
> >
> > void put_pages_list(struct list_head *pages)
> >
> > folio_batch_init(&fbatch);
> > list_for_each_entry(folio, pages, lru) {
> > - if (!folio_put_testzero(folio))
> > + if (!folio_put_testzero(folio)) {
> > + list_del(&folio->lru);
> > continue;
> > + }
> > if (folio_test_large(folio)) {
> > __folio_put_large(folio);
> > + list_del(&folio->lru);
> > continue;
> > }
>
> Thanks for testing. Sorry about this. I think I figured out what the problem
> actually is. I switched from list_for_each_entry_safe() to list_for_each_entry()
> since I was no longer deleting the entries from the list. Unfortunately, I was
> still freeing the entries as I walked the list! So it would dereference folio-
> >lru.next after giving folio back to the page allocator (which probably put it on
> the PCP list, where it would point to another free folio?)
>
> Anyway, this should do the job, without the change I asked you to test above.
> If this doesn't do the job by itself, you could try combining the two changes,
> but I don't think that will be necessary.
>
> diff --git a/mm/swap.c b/mm/swap.c
> index a910af21ba68..1d4b7713605d 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -139,10 +139,10 @@ EXPORT_SYMBOL(__folio_put); void
> put_pages_list(struct list_head *pages) {
> struct folio_batch fbatch;
> - struct folio *folio;
> + struct folio *folio, *next;
>
> folio_batch_init(&fbatch);
> - list_for_each_entry(folio, pages, lru) {
> + list_for_each_entry_safe(folio, next, pages, lru) {
> if (!folio_put_testzero(folio))
> continue;
> if (folio_test_hugetlb(folio)) {
The following change works for us.
void put_pages_list(struct list_head *pages)
{
struct folio_batch fbatch;
- struct folio *folio;
+ struct folio *folio, *next;
folio_batch_init(&fbatch);
- list_for_each_entry(folio, pages, lru) {
+ list_for_each_entry_safe(folio, next, pages, lru) {
if (!folio_put_testzero(folio))
continue;
if (folio_test_large(folio)) {
Thank you for the resolution. When can we expect a patch?
Regards
Chaitanya
