[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 a35ab0f..f49bfb7 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();