[PATCH 1/2] Revert "mm: make faultaround produce old ptes"

[Kirill A. Shutemov]

This reverts commit 5c0a85fad949212b3e059692deecdeed74ae7ec7.

The commit causes ~6% regression in unixbench.

Let's revert it for now and consider other solution for reclaim problem
later.

Signed-off-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
Reported-by: "Huang, Ying" <ying.hu...@intel.com>
---
 include/linux/mm.h |  2 +-
 mm/filemap.c       |  2 +-
 mm/memory.c        | 23 +++++------------------
 3 files changed, 7 insertions(+), 20 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 5df5feb49575..ece042dfe23c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -602,7 +602,7 @@ static inline pte_t maybe_mkwrite(pte_t pte, struct 
vm_area_struct *vma)
 }
 
 void do_set_pte(struct vm_area_struct *vma, unsigned long address,
-               struct page *page, pte_t *pte, bool write, bool anon, bool old);
+               struct page *page, pte_t *pte, bool write, bool anon);
 #endif
 
 /*
diff --git a/mm/filemap.c b/mm/filemap.c
index 00ae878b2a38..20f3b1f33f0e 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2186,7 +2186,7 @@ repeat:
                if (file->f_ra.mmap_miss > 0)
                        file->f_ra.mmap_miss--;
                addr = address + (page->index - vmf->pgoff) * PAGE_SIZE;
-               do_set_pte(vma, addr, page, pte, false, false, true);
+               do_set_pte(vma, addr, page, pte, false, false);
                unlock_page(page);
                goto next;
 unlock:
diff --git a/mm/memory.c b/mm/memory.c
index 15322b73636b..61fe7e7b56bf 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2877,7 +2877,7 @@ static int __do_fault(struct vm_area_struct *vma, 
unsigned long address,
  * vm_ops->map_pages.
  */
 void do_set_pte(struct vm_area_struct *vma, unsigned long address,
-               struct page *page, pte_t *pte, bool write, bool anon, bool old)
+               struct page *page, pte_t *pte, bool write, bool anon)
 {
        pte_t entry;
 
@@ -2885,8 +2885,6 @@ void do_set_pte(struct vm_area_struct *vma, unsigned long 
address,
        entry = mk_pte(page, vma->vm_page_prot);
        if (write)
                entry = maybe_mkwrite(pte_mkdirty(entry), vma);
-       if (old)
-               entry = pte_mkold(entry);
        if (anon) {
                inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
                page_add_new_anon_rmap(page, vma, address, false);
@@ -3032,20 +3030,9 @@ static int do_read_fault(struct mm_struct *mm, struct 
vm_area_struct *vma,
         */
        if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
                pte = pte_offset_map_lock(mm, pmd, address, &ptl);
-               if (!pte_same(*pte, orig_pte))
-                       goto unlock_out;
                do_fault_around(vma, address, pte, pgoff, flags);
-               /* Check if the fault is handled by faultaround */
-               if (!pte_same(*pte, orig_pte)) {
-                       /*
-                        * Faultaround produce old pte, but the pte we've
-                        * handler fault for should be young.
-                        */
-                       pte_t entry = pte_mkyoung(*pte);
-                       if (ptep_set_access_flags(vma, address, pte, entry, 0))
-                               update_mmu_cache(vma, address, pte);
+               if (!pte_same(*pte, orig_pte))
                        goto unlock_out;
-               }
                pte_unmap_unlock(pte, ptl);
        }
 
@@ -3060,7 +3047,7 @@ static int do_read_fault(struct mm_struct *mm, struct 
vm_area_struct *vma,
                put_page(fault_page);
                return ret;
        }
-       do_set_pte(vma, address, fault_page, pte, false, false, false);
+       do_set_pte(vma, address, fault_page, pte, false, false);
        unlock_page(fault_page);
 unlock_out:
        pte_unmap_unlock(pte, ptl);
@@ -3111,7 +3098,7 @@ static int do_cow_fault(struct mm_struct *mm, struct 
vm_area_struct *vma,
                }
                goto uncharge_out;
        }
-       do_set_pte(vma, address, new_page, pte, true, true, false);
+       do_set_pte(vma, address, new_page, pte, true, true);
        mem_cgroup_commit_charge(new_page, memcg, false, false);
        lru_cache_add_active_or_unevictable(new_page, vma);
        pte_unmap_unlock(pte, ptl);
@@ -3164,7 +3151,7 @@ static int do_shared_fault(struct mm_struct *mm, struct 
vm_area_struct *vma,
                put_page(fault_page);
                return ret;
        }
-       do_set_pte(vma, address, fault_page, pte, true, false, false);
+       do_set_pte(vma, address, fault_page, pte, true, false);
        pte_unmap_unlock(pte, ptl);
 
        if (set_page_dirty(fault_page))
-- 
2.8.1