1 files changed, 30 insertions, 7 deletions

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 4c14d4289b61..638edabaff71 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -19,7 +19,8 @@
 #include <linux/mempolicy.h>
 #include <linux/personality.h>
 #include <linux/syscalls.h>
-
+#include <linux/swap.h>
+#include <linux/swapops.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 #include <asm/cacheflush.h>
@@ -28,12 +29,13 @@
 static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
                 unsigned long addr, unsigned long end, pgprot_t newprot)
 {
-        pte_t *pte;
+        pte_t *pte, oldpte;
         spinlock_t *ptl;
 
         pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
         do {
-                if (pte_present(*pte)) {
+                oldpte = *pte;
+                if (pte_present(oldpte)) {
                         pte_t ptent;
 
                         /* Avoid an SMP race with hardware updated dirty/clean
@@ -43,7 +45,22 @@ static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
                         ptent = pte_modify(ptep_get_and_clear(mm, addr, pte), newprot);
                         set_pte_at(mm, addr, pte, ptent);
                         lazy_mmu_prot_update(ptent);
+#ifdef CONFIG_MIGRATION
+                } else if (!pte_file(oldpte)) {
+                        swp_entry_t entry = pte_to_swp_entry(oldpte);
+
+                        if (is_write_migration_entry(entry)) {
+                                /*
+                                 * A protection check is difficult so
+                                 * just be safe and disable write
+                                 */
+                                make_migration_entry_read(&entry);
+                                set_pte_at(mm, addr, pte,
+                                        swp_entry_to_pte(entry));
+                        }
+#endif
                 }
+
         } while (pte++, addr += PAGE_SIZE, addr != end);
         pte_unmap_unlock(pte - 1, ptl);
 }
@@ -106,6 +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;
@@ -132,8 +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.
          */
@@ -160,6 +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.
@@ -205,8 +229,7 @@ sys_mprotect(unsigned long start, size_t len, unsigned long prot)
         /*
          * Does the application expect PROT_READ to imply PROT_EXEC:
          */
-        if (unlikely((prot & PROT_READ) &&
-                        (current->personality & READ_IMPLIES_EXEC)))
+        if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
                 prot |= PROT_EXEC;
 
         vm_flags = calc_vm_prot_bits(prot);