Merge tag 'module_init-alternate_initcall-v4.1-rc8' of git://git.kernel.org/pub/scm...

[firefly-linux-kernel-4.4.55.git] / mm / mprotect.c

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 88584838e7046bec724d68c0cafcd94eec65a040..e7d6f1171ecb6ec453e62edd88cc258b31cfe9f3 100644 (file)
--- 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);