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-rw-r--r--mm/mprotect.c11
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);