+ vmscan-set-up-pagevec-as-late-as-possible-in-shrink_page_list.patch added to -mm tree

+ vmscan-set-up-pagevec-as-late-as-possible-in-shrink_page_list.patch added to -mm tree

[akpm]

The patch titled
     vmscan: set up pagevec as late as possible in shrink_page_list()
has been added to the -mm tree.  Its filename is
     vmscan-set-up-pagevec-as-late-as-possible-in-shrink_page_list.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/SubmitChecklist when testing your code ***

See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this

The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/

------------------------------------------------------
Subject: vmscan: set up pagevec as late as possible in shrink_page_list()
From: Mel Gorman <mel@csn.ul.ie>

shrink_page_list() sets up a pagevec to release pages as according as they
are free.  It uses significant amounts of stack on the pagevec.  This
patch adds pages to be freed via pagevec to a linked list which is then
freed en-masse at the end.  This avoids using stack in the main path that
potentially calls writepage().

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michael Rubin <mrubin@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/vmscan.c |   36 ++++++++++++++++++++++++++++--------
 1 file changed, 28 insertions(+), 8 deletions(-)

diff -puN mm/vmscan.c~vmscan-set-up-pagevec-as-late-as-possible-in-shrink_page_list mm/vmscan.c
--- a/mm/vmscan.c~vmscan-set-up-pagevec-as-late-as-possible-in-shrink_page_list
+++ a/mm/vmscan.c
@@ -620,6 +620,24 @@ static enum page_references page_check_r
 	return PAGEREF_RECLAIM;
 }
 
+static noinline_for_stack void free_page_list(struct list_head *free_pages)
+{
+	struct pagevec freed_pvec;
+	struct page *page, *tmp;
+
+	pagevec_init(&freed_pvec, 1);
+
+	list_for_each_entry_safe(page, tmp, free_pages, lru) {
+		list_del(&page->lru);
+		if (!pagevec_add(&freed_pvec, page)) {
+			__pagevec_free(&freed_pvec);
+			pagevec_reinit(&freed_pvec);
+		}
+	}
+
+	pagevec_free(&freed_pvec);
+}
+
 /*
  * shrink_page_list() returns the number of reclaimed pages
  */
@@ -628,13 +646,12 @@ static unsigned long shrink_page_list(st
 					enum pageout_io sync_writeback)
 {
 	LIST_HEAD(ret_pages);
-	struct pagevec freed_pvec;
+	LIST_HEAD(free_pages);
 	int pgactivate = 0;
 	unsigned long nr_reclaimed = 0;
 
 	cond_resched();
 
-	pagevec_init(&freed_pvec, 1);
 	while (!list_empty(page_list)) {
 		enum page_references references;
 		struct address_space *mapping;
@@ -809,10 +826,12 @@ static unsigned long shrink_page_list(st
 		__clear_page_locked(page);
 free_it:
 		nr_reclaimed++;
-		if (!pagevec_add(&freed_pvec, page)) {
-			__pagevec_free(&freed_pvec);
-			pagevec_reinit(&freed_pvec);
-		}
+
+		/*
+		 * Is there need to periodically free_page_list? It would
+		 * appear not as the counts should be low
+		 */
+		list_add(&page->lru, &free_pages);
 		continue;
 
 cull_mlocked:
@@ -835,9 +854,10 @@ keep:
 		list_add(&page->lru, &ret_pages);
 		VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
 	}
+
+	free_page_list(&free_pages);
+
 	list_splice(&ret_pages, page_list);
-	if (pagevec_count(&freed_pvec))
-		__pagevec_free(&freed_pvec);
 	count_vm_events(PGACTIVATE, pgactivate);
 	return nr_reclaimed;
 }
_

Patches currently in -mm which might be from mel@csn.ul.ie are

mm-vmscan-fix-mapping-use-after-free.patch
linux-next.patch
hugetlb-call-mmu-notifiers-on-hugepage-cow.patch
mm-rename-anon_vma_lock-to-vma_lock_anon_vma.patch
mm-change-direct-call-of-spin_lockanon_vma-lock-to-inline-function.patch
mm-track-the-root-oldest-anon_vma.patch
mm-always-lock-the-root-oldest-anon_vma.patch
mm-extend-ksm-refcounts-to-the-anon_vma-root.patch
mm-extend-ksm-refcounts-to-the-anon_vma-root-fix.patch
vmscan-tracing-add-trace-events-for-kswapd-wakeup-sleeping-and-direct-reclaim.patch
vmscan-tracing-add-trace-events-for-lru-page-isolation.patch
vmscan-tracing-add-trace-events-for-lru-page-isolation-checkpatch-fixes.patch
vmscan-tracing-add-trace-event-when-a-page-is-written.patch
vmscan-tracing-add-a-postprocessing-script-for-reclaim-related-ftrace-events.patch
vmscan-kill-prev_priority-completely.patch
vmscan-simplify-shrink_inactive_list.patch
vmscan-simplify-shrink_inactive_list-checkpatch-fixes.patch
vmscan-remove-unnecessary-temporary-vars-in-do_try_to_free_pages.patch
vmscan-remove-unnecessary-temporary-vars-in-do_try_to_free_pages-checkpatch-fixes.patch
vmscan-set-up-pagevec-as-late-as-possible-in-shrink_inactive_list.patch
vmscan-set-up-pagevec-as-late-as-possible-in-shrink_page_list.patch
vmscan-update-isolated-page-counters-outside-of-main-path-in-shrink_inactive_list.patch
delay-accounting-re-implement-c-for-getdelaysc-to-report-information-on-a-target-command.patch
delay-accounting-re-implement-c-for-getdelaysc-to-report-information-on-a-target-command-checkpatch-fixes.patch
add-debugging-aid-for-memory-initialisation-problems.patch