Pull bugzilla-5737 into release branch

[pandora-kernel.git] / mm / mprotect.c

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 14f93e6..638edab 100644 (file)
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -123,6 +123,7 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
        unsigned long oldflags = vma->vm_flags;
        long nrpages = (end - start) >> PAGE_SHIFT;
        unsigned long charged = 0;
+       unsigned int mask;
        pgprot_t newprot;
        pgoff_t pgoff;
        int error;
@@ -149,8 +150,6 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
                }
        }
 
-       newprot = protection_map[newflags & 0xf];
-
        /*
         * First try to merge with previous and/or next vma.
         */
@@ -177,6 +176,14 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
        }
 
 success:
+       /* Don't make the VMA automatically writable if it's shared, but the
+        * backer wishes to know when pages are first written to */
+       mask = VM_READ|VM_WRITE|VM_EXEC|VM_SHARED;
+       if (vma->vm_ops && vma->vm_ops->page_mkwrite)
+               mask &= ~VM_SHARED;
+
+       newprot = protection_map[newflags & mask];
+
        /*
         * vm_flags and vm_page_prot are protected by the mmap_sem
         * held in write mode.