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From: Alex Shi <alex.shi@linux.alibaba.com>
To: akpm@linux-foundation.org, mgorman@techsingularity.net,
	tj@kernel.org, hughd@google.com, khlebnikov@yandex-team.ru,
	daniel.m.jordan@oracle.com, yang.shi@linux.alibaba.com,
	willy@infradead.org, hannes@cmpxchg.org, lkp@intel.com,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	cgroups@vger.kernel.org, shakeelb@google.com,
	iamjoonsoo.kim@lge.com, richard.weiyang@gmail.com,
	kirill@shutemov.name, alexander.duyck@gmail.com,
	rong.a.chen@intel.com
Subject: [PATCH v17 14/21] mm/compaction: do page isolation first in compaction
Date: Sat, 25 Jul 2020 20:59:51 +0800
Message-ID: <1595681998-19193-15-git-send-email-alex.shi@linux.alibaba.com> (raw)
In-Reply-To: <1595681998-19193-1-git-send-email-alex.shi@linux.alibaba.com>

Currently, compaction would get the lru_lock and then do page isolation
which works fine with pgdat->lru_lock, since any page isoltion would
compete for the lru_lock. If we want to change to memcg lru_lock, we
have to isolate the page before getting lru_lock, thus isoltion would
block page's memcg change which relay on page isoltion too. Then we
could safely use per memcg lru_lock later.

The new page isolation use previous introduced TestClearPageLRU() +
pgdat lru locking which will be changed to memcg lru lock later.

Hugh Dickins <hughd@google.com> fixed following bugs in this patch's
early version:

Fix lots of crashes under compaction load: isolate_migratepages_block()
must clean up appropriately when rejecting a page, setting PageLRU again
if it had been cleared; and a put_page() after get_page_unless_zero()
cannot safely be done while holding locked_lruvec - it may turn out to
be the final put_page(), which will take an lruvec lock when PageLRU.
And move __isolate_lru_page_prepare back after get_page_unless_zero to
make trylock_page() safe:
trylock_page() is not safe to use at this time: its setting PG_locked
can race with the page being freed or allocated ("Bad page"), and can
also erase flags being set by one of those "sole owners" of a freshly
allocated page who use non-atomic __SetPageFlag().

Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
---
 include/linux/swap.h |  2 +-
 mm/compaction.c      | 42 +++++++++++++++++++++++++++++++++---------
 mm/vmscan.c          | 46 ++++++++++++++++++++++++++--------------------
 3 files changed, 60 insertions(+), 30 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 2c29399b29a0..6d23d3beeff7 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -358,7 +358,7 @@ extern void lru_cache_add_active_or_unevictable(struct page *page,
 extern unsigned long zone_reclaimable_pages(struct zone *zone);
 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 					gfp_t gfp_mask, nodemask_t *mask);
-extern int __isolate_lru_page(struct page *page, isolate_mode_t mode);
+extern int __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode);
 extern unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 						  unsigned long nr_pages,
 						  gfp_t gfp_mask,
diff --git a/mm/compaction.c b/mm/compaction.c
index f14780fc296a..2da2933fe56b 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -869,6 +869,7 @@ static bool too_many_isolated(pg_data_t *pgdat)
 		if (!valid_page && IS_ALIGNED(low_pfn, pageblock_nr_pages)) {
 			if (!cc->ignore_skip_hint && get_pageblock_skip(page)) {
 				low_pfn = end_pfn;
+				page = NULL;
 				goto isolate_abort;
 			}
 			valid_page = page;
@@ -950,6 +951,21 @@ static bool too_many_isolated(pg_data_t *pgdat)
 		if (!(cc->gfp_mask & __GFP_FS) && page_mapping(page))
 			goto isolate_fail;
 
+		/*
+		 * Be careful not to clear PageLRU until after we're
+		 * sure the page is not being freed elsewhere -- the
+		 * page release code relies on it.
+		 */
+		if (unlikely(!get_page_unless_zero(page)))
+			goto isolate_fail;
+
+		if (__isolate_lru_page_prepare(page, isolate_mode) != 0)
+			goto isolate_fail_put;
+
+		/* Try isolate the page */
+		if (!TestClearPageLRU(page))
+			goto isolate_fail_put;
+
 		/* If we already hold the lock, we can skip some rechecking */
 		if (!locked) {
 			locked = compact_lock_irqsave(&pgdat->lru_lock,
@@ -962,10 +978,6 @@ static bool too_many_isolated(pg_data_t *pgdat)
 					goto isolate_abort;
 			}
 
-			/* Recheck PageLRU and PageCompound under lock */
-			if (!PageLRU(page))
-				goto isolate_fail;
-
 			/*
 			 * Page become compound since the non-locked check,
 			 * and it's on LRU. It can only be a THP so the order
@@ -973,16 +985,13 @@ static bool too_many_isolated(pg_data_t *pgdat)
 			 */
 			if (unlikely(PageCompound(page) && !cc->alloc_contig)) {
 				low_pfn += compound_nr(page) - 1;
-				goto isolate_fail;
+				SetPageLRU(page);
+				goto isolate_fail_put;
 			}
 		}
 
 		lruvec = mem_cgroup_page_lruvec(page, pgdat);
 
-		/* Try isolate the page */
-		if (__isolate_lru_page(page, isolate_mode) != 0)
-			goto isolate_fail;
-
 		/* The whole page is taken off the LRU; skip the tail pages. */
 		if (PageCompound(page))
 			low_pfn += compound_nr(page) - 1;
@@ -1011,6 +1020,15 @@ static bool too_many_isolated(pg_data_t *pgdat)
 		}
 
 		continue;
+
+isolate_fail_put:
+		/* Avoid potential deadlock in freeing page under lru_lock */
+		if (locked) {
+			spin_unlock_irqrestore(&pgdat->lru_lock, flags);
+			locked = false;
+		}
+		put_page(page);
+
 isolate_fail:
 		if (!skip_on_failure)
 			continue;
@@ -1047,9 +1065,15 @@ static bool too_many_isolated(pg_data_t *pgdat)
 	if (unlikely(low_pfn > end_pfn))
 		low_pfn = end_pfn;
 
+	page = NULL;
+
 isolate_abort:
 	if (locked)
 		spin_unlock_irqrestore(&pgdat->lru_lock, flags);
+	if (page) {
+		SetPageLRU(page);
+		put_page(page);
+	}
 
 	/*
 	 * Updated the cached scanner pfn once the pageblock has been scanned
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4183ae6b54b5..f77748adc340 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1544,20 +1544,20 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone,
  *
  * returns 0 on success, -ve errno on failure.
  */
-int __isolate_lru_page(struct page *page, isolate_mode_t mode)
+int __isolate_lru_page_prepare(struct page *page, isolate_mode_t mode)
 {
 	int ret = -EINVAL;
 
-	/* Only take pages on the LRU. */
-	if (!PageLRU(page))
-		return ret;
-
 	/* Compaction should not handle unevictable pages but CMA can do so */
 	if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE))
 		return ret;
 
 	ret = -EBUSY;
 
+	/* Only take pages on the LRU. */
+	if (!PageLRU(page))
+		return ret;
+
 	/*
 	 * To minimise LRU disruption, the caller can indicate that it only
 	 * wants to isolate pages it will be able to operate on without
@@ -1598,20 +1598,9 @@ int __isolate_lru_page(struct page *page, isolate_mode_t mode)
 	if ((mode & ISOLATE_UNMAPPED) && page_mapped(page))
 		return ret;
 
-	if (likely(get_page_unless_zero(page))) {
-		/*
-		 * Be careful not to clear PageLRU until after we're
-		 * sure the page is not being freed elsewhere -- the
-		 * page release code relies on it.
-		 */
-		ClearPageLRU(page);
-		ret = 0;
-	}
-
-	return ret;
+	return 0;
 }
 
-
 /*
  * Update LRU sizes after isolating pages. The LRU size updates must
  * be complete before mem_cgroup_update_lru_size due to a sanity check.
@@ -1691,17 +1680,34 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 		 * only when the page is being freed somewhere else.
 		 */
 		scan += nr_pages;
-		switch (__isolate_lru_page(page, mode)) {
+		switch (__isolate_lru_page_prepare(page, mode)) {
 		case 0:
+			/*
+			 * Be careful not to clear PageLRU until after we're
+			 * sure the page is not being freed elsewhere -- the
+			 * page release code relies on it.
+			 */
+			if (unlikely(!get_page_unless_zero(page)))
+				goto busy;
+
+			if (!TestClearPageLRU(page)) {
+				/*
+				 * This page may in other isolation path,
+				 * but we still hold lru_lock.
+				 */
+				put_page(page);
+				goto busy;
+			}
+
 			nr_taken += nr_pages;
 			nr_zone_taken[page_zonenum(page)] += nr_pages;
 			list_move(&page->lru, dst);
 			break;
-
+busy:
 		case -EBUSY:
 			/* else it is being freed elsewhere */
 			list_move(&page->lru, src);
-			continue;
+			break;
 
 		default:
 			BUG();
-- 
1.8.3.1



  parent reply index

Thread overview: 102+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-25 12:59 [PATCH v17 00/21] per memcg lru lock Alex Shi
2020-07-25 12:59 ` [PATCH v17 01/21] mm/vmscan: remove unnecessary lruvec adding Alex Shi
2020-08-06  3:47   ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 02/21] mm/page_idle: no unlikely double check for idle page counting Alex Shi
2020-07-25 12:59 ` [PATCH v17 03/21] mm/compaction: correct the comments of compact_defer_shift Alex Shi
2020-07-27 17:29   ` Alexander Duyck
2020-07-28 11:59     ` Alex Shi
2020-07-28 14:17       ` Alexander Duyck
2020-07-25 12:59 ` [PATCH v17 04/21] mm/compaction: rename compact_deferred as compact_should_defer Alex Shi
2020-07-25 12:59 ` [PATCH v17 05/21] mm/thp: move lru_add_page_tail func to huge_memory.c Alex Shi
2020-07-25 12:59 ` [PATCH v17 06/21] mm/thp: clean up lru_add_page_tail Alex Shi
2020-07-25 12:59 ` [PATCH v17 07/21] mm/thp: remove code path which never got into Alex Shi
2020-07-25 12:59 ` [PATCH v17 08/21] mm/thp: narrow lru locking Alex Shi
2020-07-25 12:59 ` [PATCH v17 09/21] mm/memcg: add debug checking in lock_page_memcg Alex Shi
2020-07-25 12:59 ` [PATCH v17 10/21] mm/swap: fold vm event PGROTATED into pagevec_move_tail_fn Alex Shi
2020-07-25 12:59 ` [PATCH v17 11/21] mm/lru: move lru_lock holding in func lru_note_cost_page Alex Shi
2020-08-05 21:18   ` Alexander Duyck
2020-07-25 12:59 ` [PATCH v17 12/21] mm/lru: move lock into lru_note_cost Alex Shi
2020-07-25 12:59 ` [PATCH v17 13/21] mm/lru: introduce TestClearPageLRU Alex Shi
2020-07-29  3:53   ` Alex Shi
2020-08-05 22:43     ` Alexander Duyck
2020-08-06  1:54       ` Alex Shi
2020-08-06 14:41         ` Alexander Duyck
2020-07-25 12:59 ` Alex Shi [this message]
2020-08-04 21:35   ` [PATCH v17 14/21] mm/compaction: do page isolation first in compaction Alexander Duyck
2020-08-06 18:38   ` Alexander Duyck
2020-08-07  3:24     ` Alex Shi
2020-08-07 14:51       ` Alexander Duyck
2020-08-10 13:10         ` Alex Shi
2020-08-10 14:41           ` Alexander Duyck
2020-08-11  8:22             ` Alex Shi
2020-08-11 14:47               ` Alexander Duyck
2020-08-12 11:43                 ` Alex Shi
2020-08-12 12:16                   ` Alex Shi
2020-08-12 16:51                   ` Alexander Duyck
2020-08-13  1:46                     ` Alex Shi
2020-08-13  2:17                       ` Alexander Duyck
2020-08-13  3:52                         ` Alex Shi
2020-08-13  4:02                       ` [RFC PATCH 0/3] " Alexander Duyck
2020-08-13  4:02                         ` [RFC PATCH 1/3] mm: Drop locked from isolate_migratepages_block Alexander Duyck
2020-08-13  6:56                           ` Alex Shi
2020-08-13 14:32                             ` Alexander Duyck
2020-08-14  7:25                               ` Alex Shi
2020-08-13  7:44                           ` Alex Shi
2020-08-13 14:26                             ` Alexander Duyck
2020-08-13  4:02                         ` [RFC PATCH 2/3] mm: Drop use of test_and_set_skip in favor of just setting skip Alexander Duyck
2020-08-14  7:19                           ` Alex Shi
2020-08-14 14:24                             ` Alexander Duyck
2020-08-14 21:15                               ` Alexander Duyck
2020-08-15  9:49                                 ` Alex Shi
2020-08-17 15:38                                   ` Alexander Duyck
2020-08-18  6:50                           ` Alex Shi
2020-08-13  4:02                         ` [RFC PATCH 3/3] mm: Identify compound pages sooner in isolate_migratepages_block Alexander Duyck
2020-08-14  7:20                           ` Alex Shi
2020-08-17 22:58   ` [PATCH v17 14/21] mm/compaction: do page isolation first in compaction Alexander Duyck
2020-07-25 12:59 ` [PATCH v17 15/21] mm/thp: add tail pages into lru anyway in split_huge_page() Alex Shi
2020-07-25 12:59 ` [PATCH v17 16/21] mm/swap: serialize memcg changes in pagevec_lru_move_fn Alex Shi
2020-07-25 12:59 ` [PATCH v17 17/21] mm/lru: replace pgdat lru_lock with lruvec lock Alex Shi
2020-07-27 23:34   ` Alexander Duyck
2020-07-28  7:15     ` Alex Shi
2020-07-28 11:19     ` Alex Shi
2020-07-28 14:54       ` Alexander Duyck
2020-07-29  1:00         ` Alex Shi
2020-07-29  1:27           ` Alexander Duyck
2020-07-29  2:27             ` Alex Shi
2020-07-28 15:39     ` Alex Shi
2020-07-28 15:55       ` Alexander Duyck
2020-07-29  0:48         ` Alex Shi
2020-07-29  3:54   ` Alex Shi
2020-08-06  7:41   ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 18/21] mm/lru: introduce the relock_page_lruvec function Alex Shi
2020-07-29 17:52   ` Alexander Duyck
2020-07-30  6:08     ` Alex Shi
2020-07-31 14:20       ` Alexander Duyck
2020-07-31 21:14   ` [PATCH RFC] mm: Add function for testing if the current lruvec lock is valid alexander.h.duyck
2020-07-31 23:54     ` Alex Shi
2020-08-02 18:20       ` Alexander Duyck
2020-08-04  6:13         ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 19/21] mm/vmscan: use relock for move_pages_to_lru Alex Shi
2020-08-03 22:49   ` Alexander Duyck
2020-08-04  6:23     ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 20/21] mm/pgdat: remove pgdat lru_lock Alex Shi
2020-08-03 22:42   ` Alexander Duyck
2020-08-03 22:45     ` Alexander Duyck
2020-08-04  6:22       ` Alex Shi
2020-07-25 12:59 ` [PATCH v17 21/21] mm/lru: revise the comments of lru_lock Alex Shi
2020-08-03 22:37   ` Alexander Duyck
2020-08-04 10:04     ` Alex Shi
2020-08-04 14:29       ` Alexander Duyck
2020-08-06  1:39         ` Alex Shi
2020-08-06 16:27           ` Alexander Duyck
2020-07-27  5:40 ` [PATCH v17 00/21] per memcg lru lock Alex Shi
2020-07-29 14:49   ` Alex Shi
2020-07-29 18:06     ` Hugh Dickins
2020-07-30  2:16       ` Alex Shi
2020-08-03 15:07         ` Michal Hocko
2020-08-04  6:14           ` Alex Shi
2020-07-31 21:31 ` Alexander Duyck
2020-08-04  8:36 ` Alex Shi
2020-08-04  8:36 ` Alex Shi
2020-08-04  8:37 ` Alex Shi
2020-08-04  8:37 ` Alex Shi

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