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authorHugh Dickins <hughd@google.com>2012-01-12 17:19:56 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-01-12 20:13:10 -0800
commit2bcf887963812c075f80a14e1fad8ec7e1c67acf (patch)
tree132f11eefe904653307a05b77d16f4c41866e486 /mm/swap.c
parent90b3feaec8ffb167abd8903bf111605c2f035aa8 (diff)
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mm: take pagevecs off reclaim stack
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@google.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/swap.c')
-rw-r--r--mm/swap.c19
1 files changed, 0 insertions, 19 deletions
diff --git a/mm/swap.c b/mm/swap.c
index db6defaf2e55..79c22a649a3e 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -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 *pvec, enum lru_list lru)
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