[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/arch/sparc64/mm/tlb.c b/arch/sparc64/mm/tlb.c
index 6a43f7c..8b104be 100644
--- a/arch/sparc64/mm/tlb.c
+++ b/arch/sparc64/mm/tlb.c
@@ -18,8 +18,7 @@
/* Heavily inspired by the ppc64 code. */
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers) =
- { NULL, 0, 0, 0, 0, 0, { 0 }, { NULL }, };
+DEFINE_PER_CPU(struct mmu_gather, mmu_gathers) = { 0, };
void flush_tlb_pending(void)
{
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 @@
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 @@
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();
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)
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 5d352a7..cdd4145 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -42,7 +42,6 @@
unsigned int nr; /* set to ~0U means fast mode */
unsigned int need_flush;/* Really unmapped some ptes? */
unsigned int fullmm; /* non-zero means full mm flush */
- unsigned long freed;
struct page * pages[FREE_PTE_NR];
};
@@ -63,7 +62,6 @@
tlb->nr = num_online_cpus() > 1 ? 0U : ~0U;
tlb->fullmm = full_mm_flush;
- tlb->freed = 0;
return tlb;
}
@@ -88,13 +86,6 @@
static inline void
tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
{
- int freed = tlb->freed;
- struct mm_struct *mm = tlb->mm;
- int rss = get_mm_counter(mm, rss);
-
- if (rss < freed)
- freed = rss;
- add_mm_counter(mm, rss, -freed);
tlb_flush_mmu(tlb, start, end);
/* keep the page table cache within bounds */
diff --git a/include/asm-ia64/tlb.h b/include/asm-ia64/tlb.h
index 0bbd79f..834370b 100644
--- a/include/asm-ia64/tlb.h
+++ b/include/asm-ia64/tlb.h
@@ -60,7 +60,6 @@
unsigned int nr; /* == ~0U => fast mode */
unsigned char fullmm; /* non-zero means full mm flush */
unsigned char need_flush; /* really unmapped some PTEs? */
- unsigned long freed; /* number of pages freed */
unsigned long start_addr;
unsigned long end_addr;
struct page *pages[FREE_PTE_NR];
@@ -147,7 +146,6 @@
*/
tlb->nr = (num_online_cpus() == 1) ? ~0U : 0;
tlb->fullmm = full_mm_flush;
- tlb->freed = 0;
tlb->start_addr = ~0UL;
return tlb;
}
@@ -159,13 +157,6 @@
static inline void
tlb_finish_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long end)
{
- unsigned long freed = tlb->freed;
- struct mm_struct *mm = tlb->mm;
- unsigned long rss = get_mm_counter(mm, rss);
-
- if (rss < freed)
- freed = rss;
- add_mm_counter(mm, rss, -freed);
/*
* Note: tlb->nr may be 0 at this point, so we can't rely on tlb->start_addr and
* tlb->end_addr.
diff --git a/include/asm-sparc64/tlb.h b/include/asm-sparc64/tlb.h
index 5d194ea..66138d9 100644
--- a/include/asm-sparc64/tlb.h
+++ b/include/asm-sparc64/tlb.h
@@ -27,7 +27,6 @@
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 @@
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 @@
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();
diff --git a/mm/memory.c b/mm/memory.c
index 585bb4e..51eb3857 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -582,7 +582,7 @@
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;
