1 files changed, 17 insertions, 10 deletions

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index c96314abd144..6fb6927f9e76 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -399,13 +399,20 @@ int pmdp_test_and_clear_young(struct vm_area_struct *vma,
 int ptep_clear_flush_young(struct vm_area_struct *vma,
                            unsigned long address, pte_t *ptep)
 {
-        int young;
-
-        young = ptep_test_and_clear_young(vma, address, ptep);
-        if (young)
-                flush_tlb_page(vma, address);
-
-        return young;
+        /*
+         * On x86 CPUs, clearing the accessed bit without a TLB flush
+         * doesn't cause data corruption. [ It could cause incorrect
+         * page aging and the (mistaken) reclaim of hot pages, but the
+         * chance of that should be relatively low. ]
+         *
+         * So as a performance optimization don't flush the TLB when
+         * clearing the accessed bit, it will eventually be flushed by
+         * a context switch or a VM operation anyway. [ In the rare
+         * event of it not getting flushed for a long time the delay
+         * shouldn't really matter because there's no real memory
+         * pressure for swapout to react to. ]
+         */
+        return ptep_test_and_clear_young(vma, address, ptep);
 }
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
@@ -449,9 +456,9 @@ void __init reserve_top_address(unsigned long reserve)
 {
 #ifdef CONFIG_X86_32
         BUG_ON(fixmaps_set > 0);
-        printk(KERN_INFO "Reserving virtual address space above 0x%08x\n",
-               (int)-reserve);
-        __FIXADDR_TOP = -reserve - PAGE_SIZE;
+        __FIXADDR_TOP = round_down(-reserve, 1 << PMD_SHIFT) - PAGE_SIZE;
+        printk(KERN_INFO "Reserving virtual address space above 0x%08lx (rounded to 0x%08lx)\n",
+               -reserve, __FIXADDR_TOP + PAGE_SIZE);
 #endif
 }