[PATCH v2 07/12] s390: add pte_free_defer() for pgtables sharing page

[Hugh Dickins]

On Thu, 6 Jul 2023, Gerald Schaefer wrote:
> 
> Since none of my remarks on the comments seem valid or strictly necessary
> any more, and I also could not find functional issues, I think you can add
> this patch as new version for 07/12. And I can now give you this:
> 
> Reviewed-by: Gerald Schaefer <gerald.schaefer at linux.ibm.com>

Great, thanks a lot Gerald.
The one change I'm making to it is then this merged in:

--- a/arch/s390/mm/pgalloc.c
+++ b/arch/s390/mm/pgalloc.c
@@ -455,6 +455,11 @@ void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable)
 	page = virt_to_page(pgtable);
 	SetPageActive(page);
 	page_table_free(mm, (unsigned long *)pgtable);
+	/*
+	 * page_table_free() does not do the pgste gmap_unlink() which
+	 * page_table_free_rcu() does: warn us if pgste ever reaches here.
+	 */
+	WARN_ON_ONCE(mm_alloc_pgste(mm));
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */