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[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>
This commit is contained in:
Hugh Dickins 2005-10-29 18:16:03 -07:00 committed by Linus Torvalds
parent 4d6ddfa924
commit fc2acab31b
7 changed files with 18 additions and 69 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/sparc64/mm/tlb.c
View File

@ -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)
{

15
include/asm-arm/tlb.h
View File

@ -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();

35
include/asm-arm26/tlb.h
View File

@ -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 @@ 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;
tlb->need_flush = 0;
tlb->fullmm = full_mm_flush;
return tlb;
}
@ -34,20 +31,8 @@ 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 (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 @@ tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
} 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)

9
include/asm-generic/tlb.h
View File

@ -42,7 +42,6 @@ struct mmu_gather {
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_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush)
tlb->nr = num_online_cpus() > 1 ? 0U : ~0U;
tlb->fullmm = full_mm_flush;
tlb->freed = 0;
return tlb;
}
@ -88,13 +86,6 @@ tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
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 */

9
include/asm-ia64/tlb.h
View File

@ -60,7 +60,6 @@ struct mmu_gather {
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_gather_mmu (struct mm_struct *mm, unsigned int full_mm_flush)
*/
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 @@ 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)
{
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.

14
include/asm-sparc64/tlb.h
View File

@ -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();

2
mm/memory.c
View File

@ -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;