[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>
diff --git a/include/asm-arm26/tlb.h b/include/asm-arm26/tlb.h
index c7d54ca..08ddd85 100644
--- a/include/asm-arm26/tlb.h
+++ b/include/asm-arm26/tlb.h
@@ -10,11 +10,8 @@
*/
struct mmu_gather {
struct mm_struct *mm;
- unsigned int freed;
- unsigned int fullmm;
-
- unsigned int flushes;
- unsigned int avoided_flushes;
+ unsigned int need_flush;
+ unsigned int fullmm;
};
DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
@@ -25,8 +22,8 @@
struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
tlb->mm = mm;
- tlb->freed = 0;
- tlb->fullmm = full_mm_flush;
+ tlb->need_flush = 0;
+ tlb->fullmm = full_mm_flush;
return tlb;
}
@@ -34,20 +31,8 @@
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 (freed) {
- flush_tlb_mm(mm);
- tlb->flushes++;
- } else {
- tlb->avoided_flushes++;
- }
+ if (tlb->need_flush)
+ flush_tlb_mm(tlb->mm);
/* keep the page table cache within bounds */
check_pgt_cache();
@@ -65,7 +50,13 @@
} while (0)
#define tlb_end_vma(tlb,vma) do { } while (0)
-#define tlb_remove_page(tlb,page) free_page_and_swap_cache(page)
+static inline void
+tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+ tlb->need_flush = 1;
+ free_page_and_swap_cache(page);
+}
+
#define pte_free_tlb(tlb,ptep) pte_free(ptep)
#define pmd_free_tlb(tlb,pmdp) pmd_free(pmdp)
