Replace pagevecs in putback_lru_pages() and move_active_pages_to_lru()
by lists of pages_to_free: then apply Konstantin Khlebnikov's
free_hot_cold_page_list() to them instead of pagevec_release().
Which simplifies the flow (no need to drop and retake lock whenever
pagevec fills up) and reduces stale addresses in stack backtraces
(which often showed through the pagevecs); but more importantly,
removes another 120 bytes from the deepest stacks in page reclaim.
Although I've not recently seen an actual stack overflow here with
a vanilla kernel, move_active_pages_to_lru() has often featured in
deep backtraces.
However, free_hot_cold_page_list() does not handle compound pages
(nor need it: a Transparent HugePage would have been split by the
time it reaches the call in shrink_page_list()), but it is possible
for putback_lru_pages() or move_active_pages_to_lru() to be left
holding the last reference on a THP, so must exclude the unlikely
compound case before putting on pages_to_free.
Remove pagevec_strip(), its work now done in move_active_pages_to_lru().
The pagevec in scan_mapping_unevictable_pages() remains in mm/vmscan.c,
but that is never on the reclaim path, and cannot be replaced by a list.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
---
include/linux/pagevec.h | 2 -
mm/swap.c | 19 ------------
mm/vmscan.c | 58 ++++++++++++++++++++++++++------------
3 files changed, 40 insertions(+), 39 deletions(-)
--- mmotm.orig/include/linux/pagevec.h 2011-12-22 02:53:31.000000000 -0800
+++ mmotm/include/linux/pagevec.h 2011-12-28 17:33:21.855263356 -0800
@@ -22,7 +22,6 @@ struct pagevec {
void __pagevec_release(struct pagevec *pvec);
void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru);
-void pagevec_strip(struct pagevec *pvec);
unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
pgoff_t start, unsigned nr_pages);
unsigned pagevec_lookup_tag(struct pagevec *pvec,
@@ -59,7 +58,6 @@ static inline unsigned pagevec_add(struc
return pagevec_space(pvec);
}
-
static inline void pagevec_release(struct pagevec *pvec)
{
if (pagevec_count(pvec))
--- mmotm.orig/mm/swap.c 2011-12-28 12:53:23.000000000 -0800
+++ mmotm/mm/swap.c 2011-12-28 17:37:21.071268545 -0800
@@ -23,7 +23,6 @@
#include <linux/init.h>
#include <linux/export.h>
#include <linux/mm_inline.h>
-#include <linux/buffer_head.h> /* for try_to_release_page() */
#include <linux/percpu_counter.h>
#include <linux/percpu.h>
#include <linux/cpu.h>
@@ -730,24 +729,6 @@ void ____pagevec_lru_add(struct pagevec
EXPORT_SYMBOL(____pagevec_lru_add);
-/*
- * Try to drop buffers from the pages in a pagevec
- */
-void pagevec_strip(struct pagevec *pvec)
-{
- int i;
-
- for (i = 0; i < pagevec_count(pvec); i++) {
- struct page *page = pvec->pages[i];
-
- if (page_has_private(page) && trylock_page(page)) {
- if (page_has_private(page))
- try_to_release_page(page, 0);
- unlock_page(page);
- }
- }
-}
-
/**
* pagevec_lookup - gang pagecache lookup
* @pvec: Where the resulting pages are placed
--- mmotm.orig/mm/vmscan.c 2011-12-28 17:03:07.000000000 -0800
+++ mmotm/mm/vmscan.c 2011-12-28 17:59:24.811300757 -0800
@@ -1398,12 +1398,10 @@ putback_lru_pages(struct mem_cgroup_zone
struct list_head *page_list)
{
struct page *page;
- struct pagevec pvec;
+ LIST_HEAD(pages_to_free);
struct zone *zone = mz->zone;
struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(mz);
- pagevec_init(&pvec, 1);
-
/*
* Put back any unfreeable pages.
*/
@@ -1427,17 +1425,24 @@ putback_lru_pages(struct mem_cgroup_zone
int numpages = hpage_nr_pages(page);
reclaim_stat->recent_rotated[file] += numpages;
}
- if (!pagevec_add(&pvec, page)) {
- spin_unlock_irq(&zone->lru_lock);
- __pagevec_release(&pvec);
- spin_lock_irq(&zone->lru_lock);
+ if (put_page_testzero(page)) {
+ __ClearPageLRU(page);
+ __ClearPageActive(page);
+ del_page_from_lru_list(zone, page, lru);
+
+ if (unlikely(PageCompound(page))) {
+ spin_unlock_irq(&zone->lru_lock);
+ (*get_compound_page_dtor(page))(page);
+ spin_lock_irq(&zone->lru_lock);
+ } else
+ list_add(&page->lru, &pages_to_free);
}
}
__mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
__mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
spin_unlock_irq(&zone->lru_lock);
- pagevec_release(&pvec);
+ free_hot_cold_page_list(&pages_to_free, 1);
}
static noinline_for_stack void
@@ -1647,13 +1652,23 @@ shrink_inactive_list(unsigned long nr_to
static void move_active_pages_to_lru(struct zone *zone,
struct list_head *list,
+ struct list_head *pages_to_free,
enum lru_list lru)
{
unsigned long pgmoved = 0;
- struct pagevec pvec;
struct page *page;
- pagevec_init(&pvec, 1);
+ if (buffer_heads_over_limit) {
+ spin_unlock_irq(&zone->lru_lock);
+ list_for_each_entry(page, list, lru) {
+ if (page_has_private(page) && trylock_page(page)) {
+ if (page_has_private(page))
+ try_to_release_page(page, 0);
+ unlock_page(page);
+ }
+ }
+ spin_lock_irq(&zone->lru_lock);
+ }
while (!list_empty(list)) {
struct lruvec *lruvec;
@@ -1667,12 +1682,17 @@ static void move_active_pages_to_lru(str
list_move(&page->lru, &lruvec->lists[lru]);
pgmoved += hpage_nr_pages(page);
- if (!pagevec_add(&pvec, page) || list_empty(list)) {
- spin_unlock_irq(&zone->lru_lock);
- if (buffer_heads_over_limit)
- pagevec_strip(&pvec);
- __pagevec_release(&pvec);
- spin_lock_irq(&zone->lru_lock);
+ if (put_page_testzero(page)) {
+ __ClearPageLRU(page);
+ __ClearPageActive(page);
+ del_page_from_lru_list(zone, page, lru);
+
+ if (unlikely(PageCompound(page))) {
+ spin_unlock_irq(&zone->lru_lock);
+ (*get_compound_page_dtor(page))(page);
+ spin_lock_irq(&zone->lru_lock);
+ } else
+ list_add(&page->lru, pages_to_free);
}
}
__mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
@@ -1766,12 +1786,14 @@ static void shrink_active_list(unsigned
*/
reclaim_stat->recent_rotated[file] += nr_rotated;
- move_active_pages_to_lru(zone, &l_active,
+ move_active_pages_to_lru(zone, &l_active, &l_hold,
LRU_ACTIVE + file * LRU_FILE);
- move_active_pages_to_lru(zone, &l_inactive,
+ move_active_pages_to_lru(zone, &l_inactive, &l_hold,
LRU_BASE + file * LRU_FILE);
__mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken);
spin_unlock_irq(&zone->lru_lock);
+
+ free_hot_cold_page_list(&l_hold, 1);
}
#ifdef CONFIG_SWAP
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