s390/mm: zero page cache synonyms for zEC12
To avoid cache synonyms on System zEC12 32 independent zero pages are
required, one for each combination for bits 2**12 to 2**16 of the virtual
address. To avoid wasting too much memory on small virtual systems the
number of zero pages is limited to 4 if the memory size is less or equal
to 64MB.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 49ce6bb2..9f9c315 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -63,10 +63,18 @@
break;
case 0x2097: /* z10 */
case 0x2098: /* z10 */
- default:
+ case 0x2817: /* z196 */
+ case 0x2818: /* z196 */
order = 2;
break;
+ case 0x2827: /* zEC12 */
+ default:
+ order = 5;
+ break;
}
+ /* Limit number of empty zero pages for small memory sizes */
+ if (order > 2 && totalram_pages <= 16384)
+ order = 2;
empty_zero_page = __get_free_pages(GFP_KERNEL | __GFP_ZERO, order);
if (!empty_zero_page)