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-rw-r--r--arch/x86/mm/pgtable.c21
1 files changed, 14 insertions, 7 deletions
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index c96314abd144..0004ac72dbdd 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