[PATCH] mm: rss = file_rss + anon_rss

I was lazy when we added anon_rss, and chose to change as few places as
possible.  So currently each anonymous page has to be counted twice, in rss
and in anon_rss.  Which won't be so good if those are atomic counts in some
configurations.

Change that around: keep file_rss and anon_rss separately, and add them
together (with get_mm_rss macro) when the total is needed - reading two
atomics is much cheaper than updating two atomics.  And update anon_rss
upfront, typically in memory.c, not tucked away in page_add_anon_rmap.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

6 files changed, 27 insertions, 26 deletions

diff --git a/mm/fremap.c b/mm/fremap.c
index ab23a0673c3..fd7f2a17ff3 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -39,7 +39,7 @@ static inline void zap_pte(struct mm_struct *mm, struct vm_area_struct *vma,
                                         set_page_dirty(page);
                                 page_remove_rmap(page);
                                 page_cache_release(page);
-                                dec_mm_counter(mm, rss);
+                                dec_mm_counter(mm, file_rss);
                         }
                 }
         } else {
@@ -95,7 +95,7 @@ int install_page(struct mm_struct *mm, struct vm_area_struct *vma,
 
         zap_pte(mm, vma, addr, pte);
 
-        inc_mm_counter(mm,rss);
+        inc_mm_counter(mm, file_rss);
         flush_icache_page(vma, page);
         set_pte_at(mm, addr, pte, mk_pte(page, prot));
         page_add_file_rmap(page);
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 61d38067803..094455bcbbf 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -286,7 +286,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
                         entry = *src_pte;
                         ptepage = pte_page(entry);
                         get_page(ptepage);
-                        add_mm_counter(dst, rss, HPAGE_SIZE / PAGE_SIZE);
+                        add_mm_counter(dst, file_rss, HPAGE_SIZE / PAGE_SIZE);
                         set_huge_pte_at(dst, addr, dst_pte, entry);
                 }
                 spin_unlock(&src->page_table_lock);
@@ -324,7 +324,7 @@ void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
 
                 page = pte_page(pte);
                 put_page(page);
-                add_mm_counter(mm, rss,  - (HPAGE_SIZE / PAGE_SIZE));
+                add_mm_counter(mm, file_rss, (int) -(HPAGE_SIZE / PAGE_SIZE));
         }
         flush_tlb_range(vma, start, end);
 }
@@ -386,7 +386,7 @@ int hugetlb_prefault(struct address_space *mapping, struct vm_area_struct *vma)
                                 goto out;
                         }
                 }
-                add_mm_counter(mm, rss, HPAGE_SIZE / PAGE_SIZE);
+                add_mm_counter(mm, file_rss, HPAGE_SIZE / PAGE_SIZE);
                 set_huge_pte_at(mm, addr, pte, make_huge_pte(vma, page));
         }
 out:
diff --git a/mm/memory.c b/mm/memory.c
index 51eb3857483..59d42e50fa5 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -397,9 +397,10 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
                 pte = pte_mkclean(pte);
         pte = pte_mkold(pte);
         get_page(page);
-        inc_mm_counter(dst_mm, rss);
         if (PageAnon(page))
                 inc_mm_counter(dst_mm, anon_rss);
+        else
+                inc_mm_counter(dst_mm, file_rss);
         set_pte_at(dst_mm, addr, dst_pte, pte);
         page_dup_rmap(page);
 }
@@ -581,8 +582,8 @@ static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
                                         set_page_dirty(page);
                                 if (pte_young(ptent))
                                         mark_page_accessed(page);
+                                dec_mm_counter(tlb->mm, file_rss);
                         }
-                        dec_mm_counter(tlb->mm, rss);
                         page_remove_rmap(page);
                         tlb_remove_page(tlb, page);
                         continue;
@@ -1290,13 +1291,15 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
         spin_lock(&mm->page_table_lock);
         page_table = pte_offset_map(pmd, address);
         if (likely(pte_same(*page_table, orig_pte))) {
-                if (PageAnon(old_page))
-                        dec_mm_counter(mm, anon_rss);
                 if (PageReserved(old_page))
-                        inc_mm_counter(mm, rss);
-                else
+                        inc_mm_counter(mm, anon_rss);
+                else {
                         page_remove_rmap(old_page);
-
+                        if (!PageAnon(old_page)) {
+                                inc_mm_counter(mm, anon_rss);
+                                dec_mm_counter(mm, file_rss);
+                        }
+                }
                 flush_cache_page(vma, address, pfn);
                 entry = mk_pte(new_page, vma->vm_page_prot);
                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
@@ -1701,7 +1704,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
 
         /* The page isn't present yet, go ahead with the fault. */
 
-        inc_mm_counter(mm, rss);
+        inc_mm_counter(mm, anon_rss);
         pte = mk_pte(page, vma->vm_page_prot);
         if (write_access && can_share_swap_page(page)) {
                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
@@ -1774,7 +1777,7 @@ static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
                         page_cache_release(page);
                         goto unlock;
                 }
-                inc_mm_counter(mm, rss);
+                inc_mm_counter(mm, anon_rss);
                 entry = mk_pte(page, vma->vm_page_prot);
                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
                 lru_cache_add_active(page);
@@ -1887,19 +1890,19 @@ retry:
          */
         /* Only go through if we didn't race with anybody else... */
         if (pte_none(*page_table)) {
-                if (!PageReserved(new_page))
-                        inc_mm_counter(mm, rss);
-
                 flush_icache_page(vma, new_page);
                 entry = mk_pte(new_page, vma->vm_page_prot);
                 if (write_access)
                         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
                 set_pte_at(mm, address, page_table, entry);
                 if (anon) {
+                        inc_mm_counter(mm, anon_rss);
                         lru_cache_add_active(new_page);
                         page_add_anon_rmap(new_page, vma, address);
-                } else
+                } else if (!PageReserved(new_page)) {
+                        inc_mm_counter(mm, file_rss);
                         page_add_file_rmap(new_page);
+                }
         } else {
                 /* One of our sibling threads was faster, back out. */
                 page_cache_release(new_page);
@@ -2192,7 +2195,7 @@ EXPORT_SYMBOL(vmalloc_to_pfn);
 void update_mem_hiwater(struct task_struct *tsk)
 {
         if (tsk->mm) {
-                unsigned long rss = get_mm_counter(tsk->mm, rss);
+                unsigned long rss = get_mm_rss(tsk->mm);
 
                 if (tsk->mm->hiwater_rss < rss)
                         tsk->mm->hiwater_rss = rss;
diff --git a/mm/nommu.c b/mm/nommu.c
index 0ef241ae376..599924886eb 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1083,7 +1083,7 @@ void update_mem_hiwater(struct task_struct *tsk)
         unsigned long rss;
 
         if (likely(tsk->mm)) {
-                rss = get_mm_counter(tsk->mm, rss);
+                rss = get_mm_rss(tsk->mm);
                 if (tsk->mm->hiwater_rss < rss)
                         tsk->mm->hiwater_rss = rss;
                 if (tsk->mm->hiwater_vm < tsk->mm->total_vm)
diff --git a/mm/rmap.c b/mm/rmap.c
index 1fc559e09ca..504757624cc 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -445,8 +445,6 @@ void page_add_anon_rmap(struct page *page,
 {
         BUG_ON(PageReserved(page));
 
-        inc_mm_counter(vma->vm_mm, anon_rss);
-
         if (atomic_inc_and_test(&page->_mapcount)) {
                 struct anon_vma *anon_vma = vma->anon_vma;
 
@@ -561,9 +559,9 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma)
                 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
                 BUG_ON(pte_file(*pte));
                 dec_mm_counter(mm, anon_rss);
-        }
+        } else
+                dec_mm_counter(mm, file_rss);
 
-        dec_mm_counter(mm, rss);
         page_remove_rmap(page);
         page_cache_release(page);
 
@@ -667,7 +665,7 @@ static void try_to_unmap_cluster(unsigned long cursor,
 
                 page_remove_rmap(page);
                 page_cache_release(page);
-                dec_mm_counter(mm, rss);
+                dec_mm_counter(mm, file_rss);
                 (*mapcount)--;
         }
 
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 05c85129124..296e0bbf783 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -407,7 +407,7 @@ void free_swap_and_cache(swp_entry_t entry)
 static void unuse_pte(struct vm_area_struct *vma, pte_t *pte,
                 unsigned long addr, swp_entry_t entry, struct page *page)
 {
-        inc_mm_counter(vma->vm_mm, rss);
+        inc_mm_counter(vma->vm_mm, anon_rss);
         get_page(page);
         set_pte_at(vma->vm_mm, addr, pte,
                    pte_mkold(mk_pte(page, vma->vm_page_prot)));