X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=mm%2Fmprotect.c;h=e7d6f1171ecb6ec453e62edd88cc258b31cfe9f3;hb=9d90f035310654bff86ccbccd8ccc7e0e313216d;hp=88584838e7046bec724d68c0cafcd94eec65a040;hpb=10bb15a9a5ddf148bfc52f0c683b99487f4e2c10;p=firefly-linux-kernel-4.4.55.git

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);