[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, 2 insertions, 12 deletions

diff --git a/include/asm-sparc64/tlb.h b/include/asm-sparc64/tlb.h
index 5d194eae870c..66138d959df5 100644
--- a/include/asm-sparc64/tlb.h
+++ b/include/asm-sparc64/tlb.h
@@ -27,7 +27,6 @@ struct mmu_gather {
         unsigned int need_flush;
         unsigned int fullmm;
         unsigned int tlb_nr;
-        unsigned long freed;
         unsigned long vaddrs[TLB_BATCH_NR];
         struct page *pages[FREE_PTE_NR];
 };
@@ -51,7 +50,6 @@ static inline struct mmu_gather *tlb_gather_mmu(struct mm_struct *mm, unsigned i
         mp->mm = mm;
         mp->pages_nr = num_online_cpus() > 1 ? 0U : ~0U;
         mp->fullmm = full_mm_flush;
-        mp->freed = 0;
 
         return mp;
 }
@@ -78,19 +76,11 @@ extern void smp_flush_tlb_mm(struct mm_struct *mm);
 
 static inline void tlb_finish_mmu(struct mmu_gather *mp, unsigned long start, unsigned long end)
 {
-        unsigned long freed = mp->freed;
-        struct mm_struct *mm = mp->mm;
-        unsigned long rss = get_mm_counter(mm, rss);
-
-        if (rss < freed)
-                freed = rss;
-        add_mm_counter(mm, rss, -freed);
-
         tlb_flush_mmu(mp);
 
         if (mp->fullmm) {
-                if (CTX_VALID(mm->context))
-                        do_flush_tlb_mm(mm);
+                if (CTX_VALID(mp->mm->context))
+                        do_flush_tlb_mm(mp->mm);
                 mp->fullmm = 0;
         } else
                 flush_tlb_pending();