1 files changed, 11 insertions, 0 deletions

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 88584838e704..e7d6f1171ecb 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -29,6 +29,8 @@
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 
+#include "internal.h"
+
 /*
  * For a prot_numa update we only hold mmap_sem for read so there is a
  * potential race with faulting where a pmd was temporarily none. This
@@ -322,6 +324,15 @@ success:
         change_protection(vma, start, end, vma->vm_page_prot,
                           dirty_accountable, 0);
 
+        /*
+         * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major
+         * fault on access.
+         */
+        if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED &&
+                        (newflags & VM_WRITE)) {
+                populate_vma_page_range(vma, start, end, NULL);
+        }
+
         vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
         vm_stat_account(mm, newflags, vma->vm_file, nrpages);
         perf_event_mmap(vma);