[PATCH] .text page fault SMP scalability optimization

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

diff --git a/mm/memory.c b/mm/memory.c
index d68421dd64eff746fbfbc7eeb791224fe17cac35..0f60baf6f69b36c0b0a5ddd65021be62c7150690 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1980,9 +1980,10 @@ static inline int handle_pte_fault(struct mm_struct *mm,
                pte_t *pte, pmd_t *pmd, int write_access)
 {
        pte_t entry;
+       pte_t old_entry;
        spinlock_t *ptl;
 
-       entry = *pte;
+       old_entry = entry = *pte;
        if (!pte_present(entry)) {
                if (pte_none(entry)) {
                        if (!vma->vm_ops || !vma->vm_ops->nopage)
@@ -2009,9 +2010,20 @@ static inline int handle_pte_fault(struct mm_struct *mm,
                entry = pte_mkdirty(entry);
        }
        entry = pte_mkyoung(entry);
-       ptep_set_access_flags(vma, address, pte, entry, write_access);
-       update_mmu_cache(vma, address, entry);
-       lazy_mmu_prot_update(entry);
+       if (!pte_same(old_entry, entry)) {
+               ptep_set_access_flags(vma, address, pte, entry, write_access);
+               update_mmu_cache(vma, address, entry);
+               lazy_mmu_prot_update(entry);
+       } else {
+               /*
+                * This is needed only for protection faults but the arch code
+                * is not yet telling us if this is a protection fault or not.
+                * This still avoids useless tlb flushes for .text page faults
+                * with threads.
+                */
+               if (write_access)
+                       flush_tlb_page(vma, address);
+       }
 unlock:
        pte_unmap_unlock(pte, ptl);
        return VM_FAULT_MINOR;