Merge master.kernel.org:/home/rmk/linux-2.6-mmc

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

diff --git a/mm/mremap.c b/mm/mremap.c
index 318eea5..b535438 100644 (file)
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -28,9 +28,6 @@ static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
        pud_t *pud;
        pmd_t *pmd;
 
-       /*
-        * We don't need page_table_lock: we have mmap_sem exclusively.
-        */
        pgd = pgd_offset(mm, addr);
        if (pgd_none_or_clear_bad(pgd))
                return NULL;
@@ -50,30 +47,20 @@ static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr)
 {
        pgd_t *pgd;
        pud_t *pud;
-       pmd_t *pmd = NULL;
-       pte_t *pte;
+       pmd_t *pmd;
 
-       /*
-        * We do need page_table_lock: because allocators expect that.
-        */
-       spin_lock(&mm->page_table_lock);
        pgd = pgd_offset(mm, addr);
        pud = pud_alloc(mm, pgd, addr);
        if (!pud)
-               goto out;
+               return NULL;
 
        pmd = pmd_alloc(mm, pud, addr);
        if (!pmd)
-               goto out;
+               return NULL;
+
+       if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr))
+               return NULL;
 
-       pte = pte_alloc_map(mm, pmd, addr);
-       if (!pte) {
-               pmd = NULL;
-               goto out;
-       }
-       pte_unmap(pte);
-out:
-       spin_unlock(&mm->page_table_lock);
        return pmd;
 }
 
@@ -85,6 +72,7 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
        struct address_space *mapping = NULL;
        struct mm_struct *mm = vma->vm_mm;
        pte_t *old_pte, *new_pte, pte;
+       spinlock_t *old_ptl, *new_ptl;
 
        if (vma->vm_file) {
                /*
@@ -100,9 +88,15 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
                        new_vma->vm_truncate_count = 0;
        }
 
-       spin_lock(&mm->page_table_lock);
-       old_pte = pte_offset_map(old_pmd, old_addr);
-       new_pte = pte_offset_map_nested(new_pmd, new_addr);
+       /*
+        * We don't have to worry about the ordering of src and dst
+        * pte locks because exclusive mmap_sem prevents deadlock.
+        */
+       old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl);
+       new_pte = pte_offset_map_nested(new_pmd, new_addr);
+       new_ptl = pte_lockptr(mm, new_pmd);
+       if (new_ptl != old_ptl)
+               spin_lock(new_ptl);
 
        for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE,
                                   new_pte++, new_addr += PAGE_SIZE) {
@@ -114,9 +108,10 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
                set_pte_at(mm, new_addr, new_pte, pte);
        }
 
+       if (new_ptl != old_ptl)
+               spin_unlock(new_ptl);
        pte_unmap_nested(new_pte - 1);
-       pte_unmap(old_pte - 1);
-       spin_unlock(&mm->page_table_lock);
+       pte_unmap_unlock(old_pte - 1, old_ptl);
        if (mapping)
                spin_unlock(&mapping->i_mmap_lock);
 }
@@ -167,6 +162,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
        unsigned long new_pgoff;
        unsigned long moved_len;
        unsigned long excess = 0;
+       unsigned long hiwater_vm;
        int split = 0;
 
        /*
@@ -205,9 +201,15 @@ static unsigned long move_vma(struct vm_area_struct *vma,
        }
 
        /*
-        * if we failed to move page tables we still do total_vm increment
-        * since do_munmap() will decrement it by old_len == new_len
+        * If we failed to move page tables we still do total_vm increment
+        * since do_munmap() will decrement it by old_len == new_len.
+        *
+        * Since total_vm is about to be raised artificially high for a
+        * moment, we need to restore high watermark afterwards: if stats
+        * are taken meanwhile, total_vm and hiwater_vm appear too high.
+        * If this were a serious issue, we'd add a flag to do_munmap().
         */
+       hiwater_vm = mm->hiwater_vm;
        mm->total_vm += new_len >> PAGE_SHIFT;
        vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
 
@@ -216,6 +218,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
                vm_unacct_memory(excess >> PAGE_SHIFT);
                excess = 0;
        }
+       mm->hiwater_vm = hiwater_vm;
 
        /* Restore VM_ACCOUNT if one or two pieces of vma left */
        if (excess) {