[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, 1 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 585bb4e0b97f..51eb38574830 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -582,7 +582,7 @@ static void zap_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
 				if (pte_young(ptent))
 					mark_page_accessed(page);
 			}
-			tlb->freed++;
+			dec_mm_counter(tlb->mm, rss);
 			page_remove_rmap(page);
 			tlb_remove_page(tlb, page);
 			continue;