linux-kernel - [PATCH] mm-memcontrol-do-not-kill-uncharge-batching-in-free_pages_and_swap

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Date:	Fri,  3 Oct 2014 18:06:50 +0200
From:	Michal Hocko <mhocko@...e.cz>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Johannes Weiner <hannes@...xchg.org>,
	Greg Thelen <gthelen@...gle.com>,
	Vladimir Davydov <vdavydov@...allels.com>,
	Dave Hansen <dave@...1.net>, <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH]  mm-memcontrol-do-not-kill-uncharge-batching-in-free_pages_and_swap_cache-fix.patch

count all pages because many pages might be off LRU already.

Signed-off-by: Michal Hocko <mhocko@...e.cz>
---
 mm/swap.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/mm/swap.c b/mm/swap.c
index 39affa1932ce..8a12b33936b4 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -911,13 +911,22 @@ void release_pages(struct page **pages, int nr, bool cold)
 		if (unlikely(PageCompound(page))) {
 			if (zone) {
 				spin_unlock_irqrestore(&zone->lru_lock, flags);
-				lock_batch = 0;
 				zone = NULL;
 			}
 			put_compound_page(page);
 			continue;
 		}
 
+		/*
+		 * Make sure the IRQ-safe lock-holding time does not get
+		 * excessive with a continuous string of pages from the
+		 * same zone. The lock is held only if zone != NULL.
+		 */
+		if (zone && ++lock_batch == SWAP_CLUSTER_MAX) {
+			spin_unlock_irqrestore(&zone->lru_lock, flags);
+			zone = NULL;
+		}
+
 		if (!put_page_testzero(page))
 			continue;
 
@@ -937,16 +946,6 @@ void release_pages(struct page **pages, int nr, bool cold)
 			VM_BUG_ON_PAGE(!PageLRU(page), page);
 			__ClearPageLRU(page);
 			del_page_from_lru_list(page, lruvec, page_off_lru(page));
-
-			/*
-			 * Make sure the IRQ-safe lock-holding time
-			 * does not get excessive with a continuous
-			 * string of pages from the same zone.
-			 */
-			if (++lock_batch == SWAP_CLUSTER_MAX) {
-				spin_unlock_irqrestore(&zone->lru_lock, flags);
-				zone = NULL;
-			}
 		}
 
 		/* Clear Active bit in case of parallel mark_page_accessed */
-- 
2.1.1

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