[PATCH] mm: zap_pte out of line

There used to be just one call to zap_pte, but it shouldn't be inline now
there are two.  Check for the common case pte_none before calling, and move
its rss accounting up into install_page or install_file_pte - which helps the
next patch.

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

1 files changed, 9 insertions, 10 deletions

diff --git a/mm/fremap.c b/mm/fremap.c
index 224cc1598b..7f08d10cea 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -20,34 +20,32 @@
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 
-static inline void zap_pte(struct mm_struct *mm, struct vm_area_struct *vma,
+static int zap_pte(struct mm_struct *mm, struct vm_area_struct *vma,
                         unsigned long addr, pte_t *ptep)
 {
         pte_t pte = *ptep;
+        struct page *page = NULL;
 
-        if (pte_none(pte))
-                return;
         if (pte_present(pte)) {
                 unsigned long pfn = pte_pfn(pte);
-                struct page *page;
-
                 flush_cache_page(vma, addr, pfn);
                 pte = ptep_clear_flush(vma, addr, ptep);
                 if (unlikely(!pfn_valid(pfn))) {
                         print_bad_pte(vma, pte, addr);
-                        return;
+                        goto out;
                 }
                 page = pfn_to_page(pfn);
                 if (pte_dirty(pte))
                         set_page_dirty(page);
                 page_remove_rmap(page);
                 page_cache_release(page);
-                dec_mm_counter(mm, file_rss);
         } else {
                 if (!pte_file(pte))
                         free_swap_and_cache(pte_to_swp_entry(pte));
                 pte_clear(mm, addr, ptep);
         }
+out:
+        return !!page;
 }
 
 /*
@@ -96,9 +94,9 @@ int install_page(struct mm_struct *mm, struct vm_area_struct *vma,
         if (page_mapcount(page) > INT_MAX/2)
                 goto err_unlock;
 
-        zap_pte(mm, vma, addr, pte);
+        if (pte_none(*pte) || !zap_pte(mm, vma, addr, pte))
+                inc_mm_counter(mm, file_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);
@@ -145,7 +143,8 @@ int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma,
         if (!pte)
                 goto err_unlock;
 
-        zap_pte(mm, vma, addr, pte);
+        if (!pte_none(*pte) && zap_pte(mm, vma, addr, pte))
+                dec_mm_counter(mm, file_rss);
 
         set_pte_at(mm, addr, pte, pgoff_to_pte(pgoff));
         pte_val = *pte;