mremap: avoid sending one IPI per page

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

diff --git a/mm/mremap.c b/mm/mremap.c
index 506fa44..a184f37 100644 (file)
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -80,11 +80,7 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
        struct mm_struct *mm = vma->vm_mm;
        pte_t *old_pte, *new_pte, pte;
        spinlock_t *old_ptl, *new_ptl;
-       unsigned long old_start;
 
-       old_start = old_addr;
-       mmu_notifier_invalidate_range_start(vma->vm_mm,
-                                           old_start, old_end);
        if (vma->vm_file) {
                /*
                 * Subtle point from Rajesh Venkatasubramanian: before
@@ -111,7 +107,7 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
                                   new_pte++, new_addr += PAGE_SIZE) {
                if (pte_none(*old_pte))
                        continue;
-               pte = ptep_clear_flush(vma, old_addr, old_pte);
+               pte = ptep_get_and_clear(mm, old_addr, old_pte);
                pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr);
                set_pte_at(mm, new_addr, new_pte, pte);
        }
@@ -123,7 +119,6 @@ static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd,
        pte_unmap_unlock(old_pte - 1, old_ptl);
        if (mapping)
                mutex_unlock(&mapping->i_mmap_mutex);
-       mmu_notifier_invalidate_range_end(vma->vm_mm, old_start, old_end);
 }
 
 #define LATENCY_LIMIT  (64 * PAGE_SIZE)
@@ -134,16 +129,20 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
 {
        unsigned long extent, next, old_end;
        pmd_t *old_pmd, *new_pmd;
+       bool need_flush = false;
 
        old_end = old_addr + len;
        flush_cache_range(vma, old_addr, old_end);
 
+       mmu_notifier_invalidate_range_start(vma->vm_mm, old_addr, old_end);
+
        for (; old_addr < old_end; old_addr += extent, new_addr += extent) {
                cond_resched();
                next = (old_addr + PMD_SIZE) & PMD_MASK;
-               if (next - 1 > old_end)
-                       next = old_end;
+               /* even if next overflowed, extent below will be ok */
                extent = next - old_addr;
+               if (extent > old_end - old_addr)
+                       extent = old_end - old_addr;
                old_pmd = get_old_pmd(vma->vm_mm, old_addr);
                if (!old_pmd)
                        continue;
@@ -157,7 +156,12 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
                        extent = LATENCY_LIMIT;
                move_ptes(vma, old_pmd, old_addr, old_addr + extent,
                                new_vma, new_pmd, new_addr);
+               need_flush = true;
        }
+       if (likely(need_flush))
+               flush_tlb_range(vma, old_end-len, old_addr);
+
+       mmu_notifier_invalidate_range_end(vma->vm_mm, old_end-len, old_end);
 
        return len + old_addr - old_end;        /* how much done */
 }