s390/mm: add missing ctor/dtor on page table upgrade

Commit 78966b5 ("s390: pgtable: add statistics for PUD and P4D level
page table") misses the call to pagetable_p4d_ctor() against a newly
allocated P4D table in crst_table_upgrade();

Commit 68c601d ("mm: introduce ctor/dtor at PGD level") misses the
call to pagetable_pgd_ctor() against a newly allocated PGD and the call to
pagetable_dtor() against a newly allocated P4D that is about to be freed
on crst_table_upgrade() PGD upgrade fail path.

The missed constructors and destructor break (at least) the page table
accounting when a process memory space is upgraded.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 78966b5 ("s390: pgtable: add statistics for PUD and P4D level page table")
Fixes: 68c601d ("mm: introduce ctor/dtor at PGD level")
Signed-off-by: Alexander Gordeev <[email protected]>
Reported-by: Heiko Carstens <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Suggested-by: Heiko Carstens <[email protected]>
Reviewed-by: Gerald Schaefer <[email protected]>
Acked-by: Qi Zheng <[email protected]>
Reviewed-by: Kevin Brodsky <[email protected]>
Cc: Heiko Carstens <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Alexander Gordeev

arch/s390/mm/pgalloc.c

@@ -88,12 +88,14 @@ int crst_table_upgrade(struct mm_struct *mm, unsigned long end)
 		if (unlikely(!p4d))
 			goto err_p4d;
 		crst_table_init(p4d, _REGION2_ENTRY_EMPTY);
+		pagetable_p4d_ctor(virt_to_ptdesc(p4d));
 	}
 	if (end > _REGION1_SIZE) {
 		pgd = crst_table_alloc(mm);
 		if (unlikely(!pgd))
 			goto err_pgd;
 		crst_table_init(pgd, _REGION1_ENTRY_EMPTY);
+		pagetable_pgd_ctor(virt_to_ptdesc(pgd));
 	}
 
 	spin_lock_bh(&mm->page_table_lock);
@@ -130,6 +132,7 @@ int crst_table_upgrade(struct mm_struct *mm, unsigned long end)
 	return 0;
 
 err_pgd:
+	pagetable_dtor(virt_to_ptdesc(p4d));
 	crst_table_free(mm, p4d);
 err_p4d:
 	return -ENOMEM;