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-rw-r--r--include/linux/mm.h11
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index f7606d3a091..3b337efbe53 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -56,6 +56,17 @@ extern int sysctl_legacy_va_layout;
#define __pa_symbol(x) __pa(RELOC_HIDE((unsigned long)(x), 0))
#endif
+/*
+ * To prevent common memory management code establishing
+ * a zero page mapping on a read fault.
+ * This macro should be defined within <asm/pgtable.h>.
+ * s390 does this to prevent multiplexing of hardware bits
+ * related to the physical page in case of virtualization.
+ */
+#ifndef mm_forbids_zeropage
+#define mm_forbids_zeropage(X) (0)
+#endif
+
extern unsigned long sysctl_user_reserve_kbytes;
extern unsigned long sysctl_admin_reserve_kbytes;