mm: introduce mm_forbids_zeropage function
Add a new function stub to allow architectures to disable for
an mm_structthe backing of non-present, anonymous pages with
read-only empty zero pages.
Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/mm/memory.c b/mm/memory.c
index 1cc6bfb..d722d4f4 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2640,7 +2640,7 @@
return VM_FAULT_SIGBUS;
/* Use the zero-page for reads */
- if (!(flags & FAULT_FLAG_WRITE)) {
+ if (!(flags & FAULT_FLAG_WRITE) && !mm_forbids_zeropage(mm)) {
entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
vma->vm_page_prot));
page_table = pte_offset_map_lock(mm, pmd, address, &ptl);