powerpc/vdso: Remove NULL termination element in vdso_pagelist

No need of a NULL last element in pagelists, install_special_mapping()
knows how long the list is.

Remove that element.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/e58d95ab859e3cbc9bae3c9ce2959e17d2864f5d.1601197618.git.christophe.leroy@csgroup.eu

arch/powerpc/kernel/vdso.c

@@ -743,7 +743,7 @@ static int __init vdso_init(void)
 
 #ifdef CONFIG_VDSO32
 	/* Make sure pages are in the correct state */
-	vdso32_pagelist = kcalloc(vdso32_pages + 2, sizeof(struct page *),
+	vdso32_pagelist = kcalloc(vdso32_pages + 1, sizeof(struct page *),
 				  GFP_KERNEL);
 	BUG_ON(vdso32_pagelist == NULL);
 	for (i = 0; i < vdso32_pages; i++) {
@@ -752,11 +752,10 @@ static int __init vdso_init(void)
 		vdso32_pagelist[i] = pg;
 	}
 	vdso32_pagelist[i++] = virt_to_page(vdso_data);
-	vdso32_pagelist[i] = NULL;
 #endif
 
 #ifdef CONFIG_PPC64
-	vdso64_pagelist = kcalloc(vdso64_pages + 2, sizeof(struct page *),
+	vdso64_pagelist = kcalloc(vdso64_pages + 1, sizeof(struct page *),
 				  GFP_KERNEL);
 	BUG_ON(vdso64_pagelist == NULL);
 	for (i = 0; i < vdso64_pages; i++) {
@@ -765,7 +764,6 @@ static int __init vdso_init(void)
 		vdso64_pagelist[i] = pg;
 	}
 	vdso64_pagelist[i++] = virt_to_page(vdso_data);
-	vdso64_pagelist[i] = NULL;
 #endif /* CONFIG_PPC64 */
 
 	smp_wmb();