[PATCH] Swapless page migration: add R/W migration entries

[linux-2.6-omap-h63xx.git] / mm / mprotect.c

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 5faf01ad3ef8aa13872f11456686e07f4e174df8..14f93e62270f7b2ad38fa0846c0275e8aeccf231 100644 (file)
--- 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);
 }