[PATCH] mm: tlb_finish_mmu forget rss

zap_pte_range has been counting the pages it frees in tlb->freed, then
tlb_finish_mmu has used that to update the mm's rss.  That got stranger when I
added anon_rss, yet updated it by a different route; and stranger when rss and
anon_rss became mm_counters with special access macros.  And it would no
longer be viable if we're relying on page_table_lock to stabilize the
mm_counter, but calling tlb_finish_mmu outside that lock.

Remove the mmu_gather's freed field, let tlb_finish_mmu stick to its own
business, just decrement the rss mm_counter in zap_pte_range (yes, there was
some point to batching the update, and a subsequent patch restores that).  And
forget the anal paranoia of first reading the counter to avoid going negative
- if rss does go negative, just fix that bug.

Remove the mmu_gather's flushes and avoided_flushes from arm and arm26: no use
was being made of them.  But arm26 alone was actually using the freed, in the
way some others use need_flush: give it a need_flush.  arm26 seems to prefer
spaces to tabs here: respect that.

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, 1 insertions, 14 deletions

diff --git a/include/asm-arm/tlb.h b/include/asm-arm/tlb.h
index a35ab0f2e25e..f49bfb78c221 100644
--- a/include/asm-arm/tlb.h
+++ b/include/asm-arm/tlb.h
@@ -27,11 +27,7 @@
  */
 struct mmu_gather {
         struct mm_struct        *mm;
-        unsigned int            freed;
         unsigned int            fullmm;
-
-        unsigned int            flushes;
-        unsigned int            avoided_flushes;
 };
 
 DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
@@ -42,7 +38,6 @@ tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush)
         struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
 
         tlb->mm = mm;
-        tlb->freed = 0;
         tlb->fullmm = full_mm_flush;
 
         return tlb;
@@ -51,16 +46,8 @@ tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush)
 static inline void
 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
 {
-        struct mm_struct *mm = tlb->mm;
-        unsigned long freed = tlb->freed;
-        int rss = get_mm_counter(mm, rss);
-
-        if (rss < freed)
-                freed = rss;
-        add_mm_counter(mm, rss, -freed);
-
         if (tlb->fullmm)
-                flush_tlb_mm(mm);
+                flush_tlb_mm(tlb->mm);
 
         /* keep the page table cache within bounds */
         check_pgt_cache();