[PATCH v2 0/8] per lruvec lru_lock for memcg

[PATCH v2 0/8] per lruvec lru_lock for memcg

[Alex Shi]

Hi all,

This patchset move lru_lock into lruvec, give a lru_lock for each of
lruvec, thus bring a lru_lock for each of memcg per node.

According to Daniel Jordan's suggestion, I run 64 'dd' with on 32
containers on my 2s* 8 core * HT box with the modefied case:
  https://git.kernel.org/pub/scm/linux/kernel/git/wfg/vm-scalability.git/tree/case-lru-file-readtwice

With this change above lru_lock censitive testing improved 17% with multiple
containers scenario. And no performance lose w/o mem_cgroup.

Thanks Hugh Dickins and Konstantin Khlebnikov, they both bring the same idea
7 years ago. I don't know why they didn't go further, but according to my 
testing, and google internal usage. This feathre is clearly benefit
multi-container user.

So I like to introduce it here.

v2: bypass a performance regression bug and fix some function issues

---
 Documentation/admin-guide/cgroup-v1/memcg_test.rst | 15 +++------------
 Documentation/admin-guide/cgroup-v1/memory.rst     |  6 +++---
 Documentation/trace/events-kmem.rst                |  2 +-
 Documentation/vm/unevictable-lru.rst               | 22 ++++++++--------------
 include/linux/memcontrol.h                         | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/mm_types.h                           |  2 +-
 include/linux/mmzone.h                             |  7 +++++--
 mm/compaction.c                                    | 62 ++++++++++++++++++++++++++++++++++++++++++--------------------
 mm/filemap.c                                       |  4 ++--
 mm/huge_memory.c                                   | 16 ++++++----------
 mm/memcontrol.c                                    | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++-------------
 mm/mlock.c                                         | 27 ++++++++++++++-------------
 mm/mmzone.c                                        |  1 +
 mm/page_alloc.c                                    |  1 -
 mm/page_idle.c                                     |  5 +++--
 mm/rmap.c                                          |  2 +-
 mm/swap.c                                          | 77 +++++++++++++++++++++++++++++++----------------------------------------------
 mm/vmscan.c                                        | 74 ++++++++++++++++++++++++++++++++++++++------------------------------------
 18 files changed, 277 insertions(+), 177 deletions(-)


[PATCH v2 1/8] mm/lru: add per lruvec lock for memcg
[PATCH v2 2/8] mm/lruvec: add irqsave flags into lruvec struct
[PATCH v2 3/8] mm/lru: replace pgdat lru_lock with lruvec lock
[PATCH v2 4/8] mm/lru: only change the lru_lock iff page's lruvec is
[PATCH v2 5/8] mm/pgdat: remove pgdat lru_lock
[PATCH v2 6/8] mm/lru: remove rcu_read_lock to fix performance
[PATCH v2 7/8] mm/lru: likely enhancement
[PATCH v2 8/8] mm/lru: revise the comments of lru_lock

[PATCH v2 1/8] mm/lru: add per lruvec lock for memcg

[Alex Shi]

Currently memcg still use per node pgdat->lru_lock to guard its lruvec.
That causes some lru_lock contention in a high container density system.

If we can use per lruvec lock, that could relief much of the lru_lock
contention.

The later patches will replace the pgdat->lru_lock with lruvec->lru_lock
and show the performance benefit by benchmarks.

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Hugh Dickins <hughd@google.com>
Cc: cgroups@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
 include/linux/mmzone.h | 2 ++
 mm/mmzone.c            | 1 +
 2 files changed, 3 insertions(+)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index bda20282746b..787a42d527a2 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -303,6 +303,8 @@ struct lruvec {
 	atomic_long_t			inactive_age;
 	/* Refaults at the time of last reclaim cycle */
 	unsigned long			refaults;
+	/* per lruvec lru_lock for memcg */
+	spinlock_t			lru_lock;
 #ifdef CONFIG_MEMCG
 	struct pglist_data *pgdat;
 #endif
diff --git a/mm/mmzone.c b/mm/mmzone.c
index 4686fdc23bb9..3750a90ed4a0 100644
--- a/mm/mmzone.c
+++ b/mm/mmzone.c
@@ -91,6 +91,7 @@ void lruvec_init(struct lruvec *lruvec)
 	enum lru_list lru;
 
 	memset(lruvec, 0, sizeof(struct lruvec));
+	spin_lock_init(&lruvec->lru_lock);
 
 	for_each_lru(lru)
 		INIT_LIST_HEAD(&lruvec->lists[lru]);
-- 
1.8.3.1

[PATCH v2 2/8] mm/lruvec: add irqsave flags into lruvec struct

[Alex Shi]

We need a flags vaiable to save state when do irqsave action, declare it
here would make code more clear/clean.

Rong Chen <rong.a.chen@intel.com> report the flag variable needs to move
the tail of lruvec struct otherwise it causes 18% regressions of
vm-scalability testing on his machine. Add the flags and lru_lock to
both near struct tail.

Originally-from: Hugh Dickins <hughd@google.com>
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
CC: Rong Chen <rong.a.chen@intel.com>
Cc: cgroups@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
 include/linux/mmzone.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 787a42d527a2..da00615baa52 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -305,6 +305,8 @@ struct lruvec {
 	unsigned long			refaults;
 	/* per lruvec lru_lock for memcg */
 	spinlock_t			lru_lock;
+	/* flags for irqsave */
+	unsigned long			flags;
 #ifdef CONFIG_MEMCG
 	struct pglist_data *pgdat;
 #endif
-- 
1.8.3.1

[PATCH v2 3/8] mm/lru: replace pgdat lru_lock with lruvec lock

[Alex Shi]

This patchset move lru_lock into lruvec, give a lru_lock for each of
lruvec, thus bring a lru_lock for each of memcg per node.

This is the main patch to replace per node lru_lock with per memcg
lruvec lock. It also fold the irqsave flags into lruvec.

We introduce function lock_page_lruvec, it's same as vanilla pgdat lock
when memory cgroup unset, w/o memcg, the function will keep repin the
lruvec's lock to guard from page->mem_cgroup changes in page
migrations between memcgs. (Thanks Hugh Dickins and Konstantin
Khlebnikov reminder on this. Than the core logical is same as their
previous patchs)

According to Daniel Jordan's suggestion, I run 64 'dd' with on 32
containers on my 2s* 8 core * HT box with the modefied case:
  https://git.kernel.org/pub/scm/linux/kernel/git/wfg/vm-scalability.git/tree/case-lru-file-readtwice

With this and later patches, the dd performance is 144MB/s, the vanilla
kernel performance is 123MB/s. 17% performance increased.

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Chris Down <chris@chrisdown.name>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Qian Cai <cai@lca.pw>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: David Rientjes <rientjes@google.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: swkhack <swkhack@gmail.com>
Cc: "Potyra, Stefan" <Stefan.Potyra@elektrobit.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Colin Ian King <colin.king@canonical.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: cgroups@vger.kernel.org
---
 include/linux/memcontrol.h | 23 ++++++++++++++
 mm/compaction.c            | 62 ++++++++++++++++++++++++------------
 mm/huge_memory.c           | 16 ++++------
 mm/memcontrol.c            | 64 +++++++++++++++++++++++++++++--------
 mm/mlock.c                 | 31 +++++++++---------
 mm/page_idle.c             |  5 +--
 mm/swap.c                  | 79 +++++++++++++++++++---------------------------
 mm/vmscan.c                | 58 ++++++++++++++++------------------
 8 files changed, 201 insertions(+), 137 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index ae703ea3ef48..1c1e68537eca 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -428,6 +428,9 @@ static inline struct lruvec *mem_cgroup_lruvec(struct pglist_data *pgdat,
 
 struct lruvec *mem_cgroup_page_lruvec(struct page *, struct pglist_data *);
 
+struct lruvec *lock_page_lruvec_irq(struct page *, struct pglist_data *);
+struct lruvec *lock_page_lruvec_irqsave(struct page *, struct pglist_data *);
+
 struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
 
 struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm);
@@ -911,6 +914,26 @@ static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page,
 	return &pgdat->lruvec;
 }
 
+static inline struct lruvec *lock_page_lruvec_irq(struct page *page,
+						struct pglist_data *pgdat)
+{
+	struct lruvec *lruvec = mem_cgroup_page_lruvec(page, pgdat);
+
+	spin_lock_irq(&lruvec->lru_lock);
+
+	return lruvec;
+}
+
+static inline struct lruvec *lock_page_lruvec_irqsave(struct page *page,
+						struct pglist_data *pgdat)
+{
+	struct lruvec *lruvec = mem_cgroup_page_lruvec(page, pgdat);
+
+	spin_lock_irqsave(&lruvec->lru_lock, lruvec->flags);
+
+	return lruvec;
+}
+
 static inline bool mm_match_cgroup(struct mm_struct *mm,
 		struct mem_cgroup *memcg)
 {
diff --git a/mm/compaction.c b/mm/compaction.c
index 672d3c78c6ab..6bf9c4866f33 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -785,8 +785,7 @@ static bool too_many_isolated(pg_data_t *pgdat)
 	pg_data_t *pgdat = cc->zone->zone_pgdat;
 	unsigned long nr_scanned = 0, nr_isolated = 0;
 	struct lruvec *lruvec;
-	unsigned long flags = 0;
-	bool locked = false;
+	struct lruvec *locked_lruvec = NULL;
 	struct page *page = NULL, *valid_page = NULL;
 	unsigned long start_pfn = low_pfn;
 	bool skip_on_failure = false;
@@ -846,11 +845,21 @@ static bool too_many_isolated(pg_data_t *pgdat)
 		 * contention, to give chance to IRQs. Abort completely if
 		 * a fatal signal is pending.
 		 */
-		if (!(low_pfn % SWAP_CLUSTER_MAX)
-		    && compact_unlock_should_abort(&pgdat->lru_lock,
-					    flags, &locked, cc)) {
-			low_pfn = 0;
-			goto fatal_pending;
+		if (!(low_pfn % SWAP_CLUSTER_MAX)) {
+			if (locked_lruvec) {
+				spin_unlock_irqrestore(&locked_lruvec->lru_lock,
+							locked_lruvec->flags);
+				locked_lruvec = NULL;
+			}
+
+			if (fatal_signal_pending(current)) {
+				cc->contended = true;
+
+				low_pfn = 0;
+				goto fatal_pending;
+			}
+
+			cond_resched();
 		}
 
 		if (!pfn_valid_within(low_pfn))
@@ -919,10 +928,10 @@ static bool too_many_isolated(pg_data_t *pgdat)
 			 */
 			if (unlikely(__PageMovable(page)) &&
 					!PageIsolated(page)) {
-				if (locked) {
-					spin_unlock_irqrestore(&pgdat->lru_lock,
-									flags);
-					locked = false;
+				if (locked_lruvec) {
+					spin_unlock_irqrestore(&locked_lruvec->lru_lock,
+							locked_lruvec->flags);
+					locked_lruvec = NULL;
 				}
 
 				if (!isolate_movable_page(page, isolate_mode))
@@ -948,10 +957,22 @@ static bool too_many_isolated(pg_data_t *pgdat)
 		if (!(cc->gfp_mask & __GFP_FS) && page_mapping(page))
 			goto isolate_fail;
 
+reget_lruvec:
+		lruvec = mem_cgroup_page_lruvec(page, pgdat);
+
 		/* If we already hold the lock, we can skip some rechecking */
-		if (!locked) {
-			locked = compact_lock_irqsave(&pgdat->lru_lock,
-								&flags, cc);
+		if (lruvec != locked_lruvec) {
+			if (locked_lruvec) {
+				spin_unlock_irqrestore(&locked_lruvec->lru_lock,
+						locked_lruvec->flags);
+				locked_lruvec = NULL;
+			}
+			if (compact_lock_irqsave(&lruvec->lru_lock,
+							&lruvec->flags, cc))
+				locked_lruvec = lruvec;
+
+			if (lruvec != mem_cgroup_page_lruvec(page, pgdat))
+				goto reget_lruvec;
 
 			/* Try get exclusive access under lock */
 			if (!skip_updated) {
@@ -975,7 +996,6 @@ static bool too_many_isolated(pg_data_t *pgdat)
 			}
 		}
 
-		lruvec = mem_cgroup_page_lruvec(page, pgdat);
 
 		/* Try isolate the page */
 		if (__isolate_lru_page(page, isolate_mode) != 0)
@@ -1016,9 +1036,10 @@ static bool too_many_isolated(pg_data_t *pgdat)
 		 * page anyway.
 		 */
 		if (nr_isolated) {
-			if (locked) {
-				spin_unlock_irqrestore(&pgdat->lru_lock, flags);
-				locked = false;
+			if (locked_lruvec) {
+				spin_unlock_irqrestore(&locked_lruvec->lru_lock,
+						locked_lruvec->flags);
+				locked_lruvec = NULL;
 			}
 			putback_movable_pages(&cc->migratepages);
 			cc->nr_migratepages = 0;
@@ -1043,8 +1064,9 @@ static bool too_many_isolated(pg_data_t *pgdat)
 		low_pfn = end_pfn;
 
 isolate_abort:
-	if (locked)
-		spin_unlock_irqrestore(&pgdat->lru_lock, flags);
+	if (locked_lruvec)
+		spin_unlock_irqrestore(&locked_lruvec->lru_lock,
+						locked_lruvec->flags);
 
 	/*
 	 * Updated the cached scanner pfn once the pageblock has been scanned
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 13cc93785006..4334705f2687 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2495,17 +2495,13 @@ static void __split_huge_page_tail(struct page *head, int tail,
 }
 
 static void __split_huge_page(struct page *page, struct list_head *list,
-		pgoff_t end, unsigned long flags)
+			struct lruvec *lruvec, pgoff_t end)
 {
 	struct page *head = compound_head(page);
-	pg_data_t *pgdat = page_pgdat(head);
-	struct lruvec *lruvec;
 	struct address_space *swap_cache = NULL;
 	unsigned long offset = 0;
 	int i;
 
-	lruvec = mem_cgroup_page_lruvec(head, pgdat);
-
 	/* complete memcg works before add pages to LRU */
 	mem_cgroup_split_huge_fixup(head);
 
@@ -2554,7 +2550,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 		xa_unlock(&head->mapping->i_pages);
 	}
 
-	spin_unlock_irqrestore(&pgdat->lru_lock, flags);
+	spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->flags);
 
 	remap_page(head);
 
@@ -2697,9 +2693,9 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 	struct deferred_split *ds_queue = get_deferred_split_queue(page);
 	struct anon_vma *anon_vma = NULL;
 	struct address_space *mapping = NULL;
+	struct lruvec *lruvec;
 	int count, mapcount, extra_pins, ret;
 	bool mlocked;
-	unsigned long flags;
 	pgoff_t end;
 
 	VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
@@ -2766,7 +2762,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 		lru_add_drain();
 
 	/* prevent PageLRU to go away from under us, and freeze lru stats */
-	spin_lock_irqsave(&pgdata->lru_lock, flags);
+	lruvec = lock_page_lruvec_irqsave(head, pgdata);
 
 	if (mapping) {
 		XA_STATE(xas, &mapping->i_pages, page_index(head));
@@ -2797,7 +2793,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 		}
 
 		spin_unlock(&ds_queue->split_queue_lock);
-		__split_huge_page(page, list, end, flags);
+		__split_huge_page(page, list, lruvec, end);
 		if (PageSwapCache(head)) {
 			swp_entry_t entry = { .val = page_private(head) };
 
@@ -2816,7 +2812,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
 		spin_unlock(&ds_queue->split_queue_lock);
 fail:		if (mapping)
 			xa_unlock(&mapping->i_pages);
-		spin_unlock_irqrestore(&pgdata->lru_lock, flags);
+		spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->flags);
 		remap_page(head);
 		ret = -EBUSY;
 	}
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 37592dd7ae32..d2539bac4677 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1263,6 +1263,42 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd
 	return lruvec;
 }
 
+struct lruvec *lock_page_lruvec_irq(struct page *page,
+					struct pglist_data *pgdat)
+{
+	struct lruvec *lruvec;
+
+again:
+	lruvec = mem_cgroup_page_lruvec(page, pgdat);
+	spin_lock_irq(&lruvec->lru_lock);
+
+	/* lruvec may changed in commit_charge() */
+	if (lruvec != mem_cgroup_page_lruvec(page, pgdat)) {
+		spin_unlock_irq(&lruvec->lru_lock);
+		goto again;
+	}
+
+	return lruvec;
+}
+
+struct lruvec *lock_page_lruvec_irqsave(struct page *page,
+					struct pglist_data *pgdat)
+{
+	struct lruvec *lruvec;
+
+again:
+	lruvec = mem_cgroup_page_lruvec(page, pgdat);
+	spin_lock_irqsave(&lruvec->lru_lock, lruvec->flags);
+
+	/* lruvec may changed in commit_charge() */
+	if (lruvec != mem_cgroup_page_lruvec(page, pgdat)) {
+		spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->flags);
+		goto again;
+	}
+
+	return lruvec;
+}
+
 /**
  * mem_cgroup_update_lru_size - account for adding or removing an lru page
  * @lruvec: mem_cgroup per zone lru vector
@@ -2687,41 +2723,43 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
 	css_put_many(&memcg->css, nr_pages);
 }
 
-static void lock_page_lru(struct page *page, int *isolated)
+static struct lruvec *lock_page_lru(struct page *page, int *isolated)
 {
 	pg_data_t *pgdat = page_pgdat(page);
+	struct lruvec *lruvec = lock_page_lruvec_irq(page, pgdat);
 
-	spin_lock_irq(&pgdat->lru_lock);
 	if (PageLRU(page)) {
-		struct lruvec *lruvec;
 
-		lruvec = mem_cgroup_page_lruvec(page, pgdat);
 		ClearPageLRU(page);
 		del_page_from_lru_list(page, lruvec, page_lru(page));
 		*isolated = 1;
 	} else
 		*isolated = 0;
+
+	return lruvec;
 }
 
-static void unlock_page_lru(struct page *page, int isolated)
+static void unlock_page_lru(struct page *page, int isolated,
+				struct lruvec *locked_lruvec)
 {
-	pg_data_t *pgdat = page_pgdat(page);
+	struct lruvec *lruvec;
 
-	if (isolated) {
-		struct lruvec *lruvec;
+	spin_unlock_irq(&locked_lruvec->lru_lock);
+	lruvec = lock_page_lruvec_irq(page, page_pgdat(page));
 
-		lruvec = mem_cgroup_page_lruvec(page, pgdat);
+	if (isolated) {
 		VM_BUG_ON_PAGE(PageLRU(page), page);
 		SetPageLRU(page);
 		add_page_to_lru_list(page, lruvec, page_lru(page));
 	}
-	spin_unlock_irq(&pgdat->lru_lock);
+	spin_unlock_irq(&lruvec->lru_lock);
 }
 
 static void commit_charge(struct page *page, struct mem_cgroup *memcg,
 			  bool lrucare)
 {
 	int isolated;
+	struct lruvec *lruvec;
 
 	VM_BUG_ON_PAGE(page->mem_cgroup, page);
 
@@ -2730,7 +2768,7 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg,
 	 * may already be on some other mem_cgroup's LRU.  Take care of it.
 	 */
 	if (lrucare)
-		lock_page_lru(page, &isolated);
+		lruvec = lock_page_lru(page, &isolated);
 
 	/*
 	 * Nobody should be changing or seriously looking at
@@ -2749,7 +2787,7 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg,
 	page->mem_cgroup = memcg;
 
 	if (lrucare)
-		unlock_page_lru(page, isolated);
+		unlock_page_lru(page, isolated, lruvec);
 }
 
 #ifdef CONFIG_MEMCG_KMEM
@@ -3045,7 +3083,7 @@ void __memcg_kmem_uncharge(struct page *page, int order)
 
 /*
  * Because tail pages are not marked as "used", set it. We're under
- * pgdat->lru_lock and migration entries setup in all page mappings.
+ * pgdat->lruvec.lru_lock and migration entries setup in all page mappings.
  */
 void mem_cgroup_split_huge_fixup(struct page *head)
 {
diff --git a/mm/mlock.c b/mm/mlock.c
index a72c1eeded77..b509b80b8513 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -106,12 +106,10 @@ void mlock_vma_page(struct page *page)
  * Isolate a page from LRU with optional get_page() pin.
  * Assumes lru_lock already held and page already pinned.
  */
-static bool __munlock_isolate_lru_page(struct page *page, bool getpage)
+static bool __munlock_isolate_lru_page(struct page *page,
+			struct lruvec *lruvec, bool getpage)
 {
 	if (PageLRU(page)) {
-		struct lruvec *lruvec;
-
-		lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
 		if (getpage)
 			get_page(page);
 		ClearPageLRU(page);
@@ -183,6 +181,7 @@ unsigned int munlock_vma_page(struct page *page)
 {
 	int nr_pages;
 	pg_data_t *pgdat = page_pgdat(page);
+	struct lruvec *lruvec;
 
 	/* For try_to_munlock() and to serialize with page migration */
 	BUG_ON(!PageLocked(page));
@@ -194,7 +193,7 @@ unsigned int munlock_vma_page(struct page *page)
 	 * might otherwise copy PageMlocked to part of the tail pages before
 	 * we clear it in the head page. It also stabilizes hpage_nr_pages().
 	 */
-	spin_lock_irq(&pgdat->lru_lock);
+	lruvec = lock_page_lruvec_irq(page, pgdat);
 
 	if (!TestClearPageMlocked(page)) {
 		/* Potentially, PTE-mapped THP: do not skip the rest PTEs */
@@ -205,15 +204,15 @@ unsigned int munlock_vma_page(struct page *page)
 	nr_pages = hpage_nr_pages(page);
 	__mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
 
-	if (__munlock_isolate_lru_page(page, true)) {
-		spin_unlock_irq(&pgdat->lru_lock);
+	if (__munlock_isolate_lru_page(page, lruvec, true)) {
+		spin_unlock_irq(&lruvec->lru_lock);
 		__munlock_isolated_page(page);
 		goto out;
 	}
 	__munlock_isolation_failed(page);
 
 unlock_out:
-	spin_unlock_irq(&pgdat->lru_lock);
+	spin_unlock_irq(&lruvec->lru_lock);
 
 out:
 	return nr_pages - 1;
@@ -291,28 +290,29 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
 {
 	int i;
 	int nr = pagevec_count(pvec);
-	int delta_munlocked = -nr;
 	struct pagevec pvec_putback;
+	struct lruvec *lruvec = NULL;
 	int pgrescued = 0;
 
 	pagevec_init(&pvec_putback);
 
 	/* Phase 1: page isolation */
-	spin_lock_irq(&zone->zone_pgdat->lru_lock);
 	for (i = 0; i < nr; i++) {
 		struct page *page = pvec->pages[i];
 
+		lruvec = lock_page_lruvec_irq(page, page_pgdat(page));
+
 		if (TestClearPageMlocked(page)) {
 			/*
 			 * We already have pin from follow_page_mask()
 			 * so we can spare the get_page() here.
 			 */
-			if (__munlock_isolate_lru_page(page, false))
+			if (__munlock_isolate_lru_page(page, lruvec, false)) {
+				__mod_zone_page_state(zone, NR_MLOCK,  -1);
+				spin_unlock_irq(&lruvec->lru_lock);
 				continue;
-			else
+			} else
 				__munlock_isolation_failed(page);
-		} else {
-			delta_munlocked++;
 		}
 
 		/*
@@ -323,9 +323,8 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
 		 */
 		pagevec_add(&pvec_putback, pvec->pages[i]);
 		pvec->pages[i] = NULL;
+		spin_unlock_irq(&lruvec->lru_lock);
 	}
-	__mod_zone_page_state(zone, NR_MLOCK, delta_munlocked);
-	spin_unlock_irq(&zone->zone_pgdat->lru_lock);
 
 	/* Now we can release pins of pages that we are not munlocking */
 	pagevec_release(&pvec_putback);
diff --git a/mm/page_idle.c b/mm/page_idle.c
index 295512465065..25f4b1cf3e0f 100644
--- a/mm/page_idle.c
+++ b/mm/page_idle.c
@@ -32,6 +32,7 @@ static struct page *page_idle_get_page(unsigned long pfn)
 {
 	struct page *page;
 	pg_data_t *pgdat;
+	struct lruvec *lruvec;
 
 	if (!pfn_valid(pfn))
 		return NULL;
@@ -42,12 +43,12 @@ static struct page *page_idle_get_page(unsigned long pfn)
 		return NULL;
 
 	pgdat = page_pgdat(page);
-	spin_lock_irq(&pgdat->lru_lock);
+	lruvec = lock_page_lruvec_irq(page, pgdat);
 	if (unlikely(!PageLRU(page))) {
 		put_page(page);
 		page = NULL;
 	}
-	spin_unlock_irq(&pgdat->lru_lock);
+	spin_unlock_irq(&lruvec->lru_lock);
 	return page;
 }
 
diff --git a/mm/swap.c b/mm/swap.c
index 38c3fa4308e2..267c3e262254 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -62,14 +62,12 @@ static void __page_cache_release(struct page *page)
 	if (PageLRU(page)) {
 		pg_data_t *pgdat = page_pgdat(page);
 		struct lruvec *lruvec;
-		unsigned long flags;
 
-		spin_lock_irqsave(&pgdat->lru_lock, flags);
-		lruvec = mem_cgroup_page_lruvec(page, pgdat);
+		lruvec = lock_page_lruvec_irqsave(page, pgdat);
 		VM_BUG_ON_PAGE(!PageLRU(page), page);
 		__ClearPageLRU(page);
 		del_page_from_lru_list(page, lruvec, page_off_lru(page));
-		spin_unlock_irqrestore(&pgdat->lru_lock, flags);
+		spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->flags);
 	}
 	__ClearPageWaiters(page);
 }
@@ -192,26 +190,17 @@ static void pagevec_lru_move_fn(struct pagevec *pvec,
 	void *arg)
 {
 	int i;
-	struct pglist_data *pgdat = NULL;
-	struct lruvec *lruvec;
-	unsigned long flags = 0;
+	struct lruvec *lruvec = NULL;
 
 	for (i = 0; i < pagevec_count(pvec); i++) {
 		struct page *page = pvec->pages[i];
-		struct pglist_data *pagepgdat = page_pgdat(page);
 
-		if (pagepgdat != pgdat) {
-			if (pgdat)
-				spin_unlock_irqrestore(&pgdat->lru_lock, flags);
-			pgdat = pagepgdat;
-			spin_lock_irqsave(&pgdat->lru_lock, flags);
-		}
+		lruvec = lock_page_lruvec_irqsave(page, page_pgdat(page));
 
-		lruvec = mem_cgroup_page_lruvec(page, pgdat);
 		(*move_fn)(page, lruvec, arg);
+		spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->flags);
 	}
-	if (pgdat)
-		spin_unlock_irqrestore(&pgdat->lru_lock, flags);
+
 	release_pages(pvec->pages, pvec->nr);
 	pagevec_reinit(pvec);
 }
@@ -325,11 +314,12 @@ static inline void activate_page_drain(int cpu)
 void activate_page(struct page *page)
 {
 	pg_data_t *pgdat = page_pgdat(page);
+	struct lruvec *lruvec;
 
 	page = compound_head(page);
-	spin_lock_irq(&pgdat->lru_lock);
-	__activate_page(page, mem_cgroup_page_lruvec(page, pgdat), NULL);
-	spin_unlock_irq(&pgdat->lru_lock);
+	lruvec = lock_page_lruvec_irq(page, pgdat);
+	__activate_page(page, lruvec, NULL);
+	spin_unlock_irq(&lruvec->lru_lock);
 }
 #endif
 
@@ -761,9 +751,7 @@ void release_pages(struct page **pages, int nr)
 {
 	int i;
 	LIST_HEAD(pages_to_free);
-	struct pglist_data *locked_pgdat = NULL;
-	struct lruvec *lruvec;
-	unsigned long uninitialized_var(flags);
+	struct lruvec *lruvec = NULL;
 	unsigned int uninitialized_var(lock_batch);
 
 	for (i = 0; i < nr; i++) {
@@ -772,21 +760,22 @@ void release_pages(struct page **pages, int nr)
 		/*
 		 * Make sure the IRQ-safe lock-holding time does not get
 		 * excessive with a continuous string of pages from the
-		 * same pgdat. The lock is held only if pgdat != NULL.
+		 * same lruvec. The lock is held only if lruvec != NULL.
 		 */
-		if (locked_pgdat && ++lock_batch == SWAP_CLUSTER_MAX) {
-			spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
-			locked_pgdat = NULL;
+		if (lruvec && ++lock_batch == SWAP_CLUSTER_MAX) {
+			spin_unlock_irqrestore(&lruvec->lru_lock,
+							lruvec->flags);
+			lruvec = NULL;
 		}
 
 		if (is_huge_zero_page(page))
 			continue;
 
 		if (is_zone_device_page(page)) {
-			if (locked_pgdat) {
-				spin_unlock_irqrestore(&locked_pgdat->lru_lock,
-						       flags);
-				locked_pgdat = NULL;
+			if (lruvec) {
+				spin_unlock_irqrestore(&lruvec->lru_lock,
+						       lruvec->flags);
+				lruvec = NULL;
 			}
 			/*
 			 * ZONE_DEVICE pages that return 'false' from
@@ -803,27 +792,25 @@ void release_pages(struct page **pages, int nr)
 			continue;
 
 		if (PageCompound(page)) {
-			if (locked_pgdat) {
-				spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
-				locked_pgdat = NULL;
+			if (lruvec) {
+				spin_unlock_irqrestore(&lruvec->lru_lock,
+								lruvec->flags);
+				lruvec = NULL;
 			}
 			__put_compound_page(page);
 			continue;
 		}
 
 		if (PageLRU(page)) {
-			struct pglist_data *pgdat = page_pgdat(page);
+			struct lruvec *new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
 
-			if (pgdat != locked_pgdat) {
-				if (locked_pgdat)
-					spin_unlock_irqrestore(&locked_pgdat->lru_lock,
-									flags);
+			if (new_lruvec != lruvec) {
+				if (lruvec)
+					spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->flags);
 				lock_batch = 0;
-				locked_pgdat = pgdat;
-				spin_lock_irqsave(&locked_pgdat->lru_lock, flags);
-			}
+				lruvec = lock_page_lruvec_irqsave(page, page_pgdat(page));
 
-			lruvec = mem_cgroup_page_lruvec(page, locked_pgdat);
+			}
 			VM_BUG_ON_PAGE(!PageLRU(page), page);
 			__ClearPageLRU(page);
 			del_page_from_lru_list(page, lruvec, page_off_lru(page));
@@ -835,8 +822,8 @@ void release_pages(struct page **pages, int nr)
 
 		list_add(&page->lru, &pages_to_free);
 	}
-	if (locked_pgdat)
-		spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
+	if (lruvec)
+		spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->flags);
 
 	mem_cgroup_uncharge_list(&pages_to_free);
 	free_unref_page_list(&pages_to_free);
@@ -874,7 +861,7 @@ void lru_add_page_tail(struct page *page, struct page *page_tail,
 	VM_BUG_ON_PAGE(!PageHead(page), page);
 	VM_BUG_ON_PAGE(PageCompound(page_tail), page);
 	VM_BUG_ON_PAGE(PageLRU(page_tail), page);
-	lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);
+	lockdep_assert_held(&lruvec->lru_lock);
 
 	if (!list)
 		SetPageLRU(page_tail);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index ee4eecc7e1c2..50f15d1e5f18 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1804,8 +1804,7 @@ int isolate_lru_page(struct page *page)
 		pg_data_t *pgdat = page_pgdat(page);
 		struct lruvec *lruvec;
 
-		spin_lock_irq(&pgdat->lru_lock);
-		lruvec = mem_cgroup_page_lruvec(page, pgdat);
+		lruvec = lock_page_lruvec_irq(page, pgdat);
 		if (PageLRU(page)) {
 			int lru = page_lru(page);
 			get_page(page);
@@ -1813,7 +1812,7 @@ int isolate_lru_page(struct page *page)
 			del_page_from_lru_list(page, lruvec, lru);
 			ret = 0;
 		}
-		spin_unlock_irq(&pgdat->lru_lock);
+		spin_unlock_irq(&lruvec->lru_lock);
 	}
 	return ret;
 }
@@ -1878,7 +1877,6 @@ static int too_many_isolated(struct pglist_data *pgdat, int file,
 static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
 						     struct list_head *list)
 {
-	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
 	int nr_pages, nr_moved = 0;
 	LIST_HEAD(pages_to_free);
 	struct page *page;
@@ -1889,12 +1887,11 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
 		VM_BUG_ON_PAGE(PageLRU(page), page);
 		if (unlikely(!page_evictable(page))) {
 			list_del(&page->lru);
-			spin_unlock_irq(&pgdat->lru_lock);
+			spin_unlock_irq(&lruvec->lru_lock);
 			putback_lru_page(page);
-			spin_lock_irq(&pgdat->lru_lock);
+			spin_lock_irq(&lruvec->lru_lock);
 			continue;
 		}
-		lruvec = mem_cgroup_page_lruvec(page, pgdat);
 
 		SetPageLRU(page);
 		lru = page_lru(page);
@@ -1909,9 +1906,9 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
 			del_page_from_lru_list(page, lruvec, lru);
 
 			if (unlikely(PageCompound(page))) {
-				spin_unlock_irq(&pgdat->lru_lock);
+				spin_unlock_irq(&lruvec->lru_lock);
 				(*get_compound_page_dtor(page))(page);
-				spin_lock_irq(&pgdat->lru_lock);
+				spin_lock_irq(&lruvec->lru_lock);
 			} else
 				list_add(&page->lru, &pages_to_free);
 		} else {
@@ -1974,7 +1971,7 @@ static int current_may_throttle(void)
 
 	lru_add_drain();
 
-	spin_lock_irq(&pgdat->lru_lock);
+	spin_lock_irq(&lruvec->lru_lock);
 
 	nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &page_list,
 				     &nr_scanned, sc, lru);
@@ -1986,7 +1983,7 @@ static int current_may_throttle(void)
 	if (global_reclaim(sc))
 		__count_vm_events(item, nr_scanned);
 	__count_memcg_events(lruvec_memcg(lruvec), item, nr_scanned);
-	spin_unlock_irq(&pgdat->lru_lock);
+	spin_unlock_irq(&lruvec->lru_lock);
 
 	if (nr_taken == 0)
 		return 0;
@@ -1994,7 +1991,7 @@ static int current_may_throttle(void)
 	nr_reclaimed = shrink_page_list(&page_list, pgdat, sc, 0,
 				&stat, false);
 
-	spin_lock_irq(&pgdat->lru_lock);
+	spin_lock_irq(&lruvec->lru_lock);
 
 	item = current_is_kswapd() ? PGSTEAL_KSWAPD : PGSTEAL_DIRECT;
 	if (global_reclaim(sc))
@@ -2007,7 +2004,7 @@ static int current_may_throttle(void)
 
 	__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
 
-	spin_unlock_irq(&pgdat->lru_lock);
+	spin_unlock_irq(&lruvec->lru_lock);
 
 	mem_cgroup_uncharge_list(&page_list);
 	free_unref_page_list(&page_list);
@@ -2060,7 +2057,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
 
 	lru_add_drain();
 
-	spin_lock_irq(&pgdat->lru_lock);
+	spin_lock_irq(&lruvec->lru_lock);
 
 	nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold,
 				     &nr_scanned, sc, lru);
@@ -2071,7 +2068,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
 	__count_vm_events(PGREFILL, nr_scanned);
 	__count_memcg_events(lruvec_memcg(lruvec), PGREFILL, nr_scanned);
 
-	spin_unlock_irq(&pgdat->lru_lock);
+	spin_unlock_irq(&lruvec->lru_lock);
 
 	while (!list_empty(&l_hold)) {
 		cond_resched();
@@ -2117,7 +2114,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
 	/*
 	 * Move pages back to the lru list.
 	 */
-	spin_lock_irq(&pgdat->lru_lock);
+	spin_lock_irq(&lruvec->lru_lock);
 	/*
 	 * Count referenced pages from currently used mappings as rotated,
 	 * even though only some of them are actually re-activated.  This
@@ -2135,7 +2132,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
 	__count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, nr_deactivate);
 
 	__mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
-	spin_unlock_irq(&pgdat->lru_lock);
+	spin_unlock_irq(&lruvec->lru_lock);
 
 	mem_cgroup_uncharge_list(&l_active);
 	free_unref_page_list(&l_active);
@@ -2427,7 +2424,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 	file  = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES) +
 		lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES);
 
-	spin_lock_irq(&pgdat->lru_lock);
+	spin_lock_irq(&lruvec->lru_lock);
 	if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
 		reclaim_stat->recent_scanned[0] /= 2;
 		reclaim_stat->recent_rotated[0] /= 2;
@@ -2448,7 +2445,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 
 	fp = file_prio * (reclaim_stat->recent_scanned[1] + 1);
 	fp /= reclaim_stat->recent_rotated[1] + 1;
-	spin_unlock_irq(&pgdat->lru_lock);
+	spin_unlock_irq(&lruvec->lru_lock);
 
 	fraction[0] = ap;
 	fraction[1] = fp;
@@ -4334,24 +4331,25 @@ int page_evictable(struct page *page)
  */
 void check_move_unevictable_pages(struct pagevec *pvec)
 {
-	struct lruvec *lruvec;
-	struct pglist_data *pgdat = NULL;
+	struct lruvec *lruvec = NULL;
 	int pgscanned = 0;
 	int pgrescued = 0;
 	int i;
 
 	for (i = 0; i < pvec->nr; i++) {
 		struct page *page = pvec->pages[i];
-		struct pglist_data *pagepgdat = page_pgdat(page);
+		struct pglist_data *pgdat = page_pgdat(page);
+		struct lruvec *new_lruvec = mem_cgroup_page_lruvec(page, pgdat);
+
 
 		pgscanned++;
-		if (pagepgdat != pgdat) {
-			if (pgdat)
-				spin_unlock_irq(&pgdat->lru_lock);
-			pgdat = pagepgdat;
-			spin_lock_irq(&pgdat->lru_lock);
+
+		if (lruvec != new_lruvec) {
+			if (lruvec)
+				spin_unlock_irq(&lruvec->lru_lock);
+			lruvec = new_lruvec;
+			spin_lock_irq(&lruvec->lru_lock);
 		}
-		lruvec = mem_cgroup_page_lruvec(page, pgdat);
 
 		if (!PageLRU(page) || !PageUnevictable(page))
 			continue;
@@ -4367,10 +4365,10 @@ void check_move_unevictable_pages(struct pagevec *pvec)
 		}
 	}
 
-	if (pgdat) {
+	if (lruvec) {
 		__count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
 		__count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned);
-		spin_unlock_irq(&pgdat->lru_lock);
+		spin_unlock_irq(&lruvec->lru_lock);
 	}
 }
 EXPORT_SYMBOL_GPL(check_move_unevictable_pages);
-- 
1.8.3.1

[PATCH v2 4/8] mm/lru: only change the lru_lock iff page's lruvec is different

[Alex Shi]

During the pagevec locking, a new page's lruvec is may same as
previous one. So we may save a lruvec locking if the lruvec is same as
previous one, and only change the lock iff lruvec is new.

Function named relock_page_lruvec following Hugh Dickins patch.

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Chris Down <chris@chrisdown.name>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: swkhack <swkhack@gmail.com>
Cc: "Potyra, Stefan" <Stefan.Potyra@elektrobit.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Hugh Dickins <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: cgroups@vger.kernel.org
Cc: linux-mm@kvack.org
---
 include/linux/memcontrol.h | 49 ++++++++++++++++++++++++++++++++++++++++++++++
 mm/mlock.c                 | 16 ++++++++-------
 mm/swap.c                  | 14 ++++++-------
 mm/vmscan.c                | 24 +++++++++++------------
 4 files changed, 76 insertions(+), 27 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 1c1e68537eca..2421b720d272 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1300,6 +1300,55 @@ static inline void dec_lruvec_page_state(struct page *page,
 	mod_lruvec_page_state(page, idx, -1);
 }
 
+/* Don't lock again iff page's lruvec locked */
+static inline struct lruvec *relock_page_lruvec_irq(struct page *page,
+					struct lruvec *locked_lruvec)
+{
+	struct pglist_data *pgdat = page_pgdat(page);
+	struct lruvec *lruvec;
+
+	rcu_read_lock();
+	lruvec = mem_cgroup_page_lruvec(page, pgdat);
+
+	if (locked_lruvec == lruvec) {
+		rcu_read_unlock();
+		return lruvec;
+	}
+	rcu_read_unlock();
+
+	if (locked_lruvec)
+		spin_unlock_irq(&locked_lruvec->lru_lock);
+
+	lruvec = lock_page_lruvec_irq(page, pgdat);
+
+	return lruvec;
+}
+
+/* Don't lock again iff page's lruvec locked */
+static inline struct lruvec *relock_page_lruvec_irqsave(struct page *page,
+					struct lruvec *locked_lruvec)
+{
+	struct pglist_data *pgdat = page_pgdat(page);
+	struct lruvec *lruvec;
+
+	rcu_read_lock();
+	lruvec = mem_cgroup_page_lruvec(page, pgdat);
+
+	if (locked_lruvec == lruvec) {
+		rcu_read_unlock();
+		return lruvec;
+	}
+	rcu_read_unlock();
+
+	if (locked_lruvec)
+		spin_unlock_irqrestore(&locked_lruvec->lru_lock,
+							locked_lruvec->flags);
+
+	lruvec = lock_page_lruvec_irqsave(page, pgdat);
+
+	return lruvec;
+}
+
 #ifdef CONFIG_CGROUP_WRITEBACK
 
 struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb);
diff --git a/mm/mlock.c b/mm/mlock.c
index b509b80b8513..8b3a97b62c0a 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -290,6 +290,7 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
 {
 	int i;
 	int nr = pagevec_count(pvec);
+	int delta_munlocked = -nr;
 	struct pagevec pvec_putback;
 	struct lruvec *lruvec = NULL;
 	int pgrescued = 0;
@@ -300,20 +301,19 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
 	for (i = 0; i < nr; i++) {
 		struct page *page = pvec->pages[i];
 
-		lruvec = lock_page_lruvec_irq(page, page_pgdat(page));
+		lruvec = relock_page_lruvec_irq(page, lruvec);
 
 		if (TestClearPageMlocked(page)) {
 			/*
 			 * We already have pin from follow_page_mask()
 			 * so we can spare the get_page() here.
 			 */
-			if (__munlock_isolate_lru_page(page, lruvec, false)) {
-				__mod_zone_page_state(zone, NR_MLOCK,  -1);
-				spin_unlock_irq(&lruvec->lru_lock);
+			if (__munlock_isolate_lru_page(page, lruvec, false))
 				continue;
-			} else
+			else
 				__munlock_isolation_failed(page);
-		}
+		} else
+			delta_munlocked++;
 
 		/*
 		 * We won't be munlocking this page in the next phase
@@ -323,8 +323,10 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
 		 */
 		pagevec_add(&pvec_putback, pvec->pages[i]);
 		pvec->pages[i] = NULL;
-		spin_unlock_irq(&lruvec->lru_lock);
 	}
+	__mod_zone_page_state(zone, NR_MLOCK, delta_munlocked);
+	if (lruvec)
+		spin_unlock_irq(&lruvec->lru_lock);
 
 	/* Now we can release pins of pages that we are not munlocking */
 	pagevec_release(&pvec_putback);
diff --git a/mm/swap.c b/mm/swap.c
index 267c3e262254..0639b3e9e03b 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -195,11 +195,12 @@ static void pagevec_lru_move_fn(struct pagevec *pvec,
 	for (i = 0; i < pagevec_count(pvec); i++) {
 		struct page *page = pvec->pages[i];
 
-		lruvec = lock_page_lruvec_irqsave(page, page_pgdat(page));
+		lruvec = relock_page_lruvec_irqsave(page, lruvec);
 
 		(*move_fn)(page, lruvec, arg);
-		spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->flags);
 	}
+	if (lruvec)
+		spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->flags);
 
 	release_pages(pvec->pages, pvec->nr);
 	pagevec_reinit(pvec);
@@ -802,15 +803,12 @@ void release_pages(struct page **pages, int nr)
 		}
 
 		if (PageLRU(page)) {
-			struct lruvec *new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
+			struct lruvec *pre_lruvec = lruvec;
 
-			if (new_lruvec != lruvec) {
-				if (lruvec)
-					spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->flags);
+			lruvec = relock_page_lruvec_irqsave(page, lruvec);
+			if (pre_lruvec != lruvec)
 				lock_batch = 0;
-				lruvec = lock_page_lruvec_irqsave(page, page_pgdat(page));
 
-			}
 			VM_BUG_ON_PAGE(!PageLRU(page), page);
 			__ClearPageLRU(page);
 			del_page_from_lru_list(page, lruvec, page_off_lru(page));
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 50f15d1e5f18..cbebd9b0b9c8 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1874,22 +1874,25 @@ static int too_many_isolated(struct pglist_data *pgdat, int file,
  * Returns the number of pages moved to the given lruvec.
  */
 
-static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
+static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *llvec,
 						     struct list_head *list)
 {
 	int nr_pages, nr_moved = 0;
 	LIST_HEAD(pages_to_free);
 	struct page *page;
 	enum lru_list lru;
+	struct lruvec *lruvec = llvec;
 
 	while (!list_empty(list)) {
 		page = lru_to_page(list);
+		lruvec = relock_page_lruvec_irq(page, lruvec);
+
 		VM_BUG_ON_PAGE(PageLRU(page), page);
 		if (unlikely(!page_evictable(page))) {
 			list_del(&page->lru);
 			spin_unlock_irq(&lruvec->lru_lock);
+			lruvec = NULL;
 			putback_lru_page(page);
-			spin_lock_irq(&lruvec->lru_lock);
 			continue;
 		}
 
@@ -1907,8 +1910,8 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
 
 			if (unlikely(PageCompound(page))) {
 				spin_unlock_irq(&lruvec->lru_lock);
+				lruvec = NULL;
 				(*get_compound_page_dtor(page))(page);
-				spin_lock_irq(&lruvec->lru_lock);
 			} else
 				list_add(&page->lru, &pages_to_free);
 		} else {
@@ -1916,6 +1919,11 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
 		}
 	}
 
+	if (lruvec != llvec) {
+		if (lruvec)
+			spin_unlock_irq(&lruvec->lru_lock);
+		spin_lock_irq(&llvec->lru_lock);
+	}
 	/*
 	 * To save our caller's stack, now use input list for pages to free.
 	 */
@@ -4338,18 +4346,10 @@ void check_move_unevictable_pages(struct pagevec *pvec)
 
 	for (i = 0; i < pvec->nr; i++) {
 		struct page *page = pvec->pages[i];
-		struct pglist_data *pgdat = page_pgdat(page);
-		struct lruvec *new_lruvec = mem_cgroup_page_lruvec(page, pgdat);
-
 
 		pgscanned++;
 
-		if (lruvec != new_lruvec) {
-			if (lruvec)
-				spin_unlock_irq(&lruvec->lru_lock);
-			lruvec = new_lruvec;
-			spin_lock_irq(&lruvec->lru_lock);
-		}
+		lruvec = relock_page_lruvec_irq(page, lruvec);
 
 		if (!PageLRU(page) || !PageUnevictable(page))
 			continue;
-- 
1.8.3.1

[PATCH v2 5/8] mm/pgdat: remove pgdat lru_lock

[Alex Shi]

Now pgdat was replaced by lruvec lock. It's not used anymore.

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Cc: cgroups@vger.kernel.org
---
 include/linux/mmzone.h | 1 -
 mm/page_alloc.c        | 1 -
 2 files changed, 2 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index da00615baa52..3b6029bcb577 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -759,7 +759,6 @@ struct deferred_split {
 
 	/* Write-intensive fields used by page reclaim */
 	ZONE_PADDING(_pad1_)
-	spinlock_t		lru_lock;
 
 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
 	/*
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f391c0c4ed1d..ffc30375c05b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6710,7 +6710,6 @@ static void __meminit pgdat_init_internals(struct pglist_data *pgdat)
 	init_waitqueue_head(&pgdat->pfmemalloc_wait);
 
 	pgdat_page_ext_init(pgdat);
-	spin_lock_init(&pgdat->lru_lock);
 	lruvec_init(node_lruvec(pgdat));
 }
 
-- 
1.8.3.1

[PATCH v2 6/8] mm/lru: remove rcu_read_lock to fix performance regression

[Alex Shi]

Intel 0day report there are performance regression on this patchset.
The detailed info points to rcu_read_lock + PROVE_LOCKING which causes
queued_spin_lock_slowpath waiting too long time to get lock.
Remove rcu_read_lock is safe here since we had a spinlock hold.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Chris Down <chris@chrisdown.name>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
 include/linux/memcontrol.h | 29 ++++++++++++-----------------
 1 file changed, 12 insertions(+), 17 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 2421b720d272..f869897a68f0 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1307,20 +1307,18 @@ static inline struct lruvec *relock_page_lruvec_irq(struct page *page,
 	struct pglist_data *pgdat = page_pgdat(page);
 	struct lruvec *lruvec;
 
-	rcu_read_lock();
+	if (!locked_lruvec)
+		goto lock;
+
 	lruvec = mem_cgroup_page_lruvec(page, pgdat);
 
-	if (locked_lruvec == lruvec) {
-		rcu_read_unlock();
+	if (locked_lruvec == lruvec)
 		return lruvec;
-	}
-	rcu_read_unlock();
 
-	if (locked_lruvec)
-		spin_unlock_irq(&locked_lruvec->lru_lock);
+	spin_unlock_irq(&locked_lruvec->lru_lock);
 
+lock:
 	lruvec = lock_page_lruvec_irq(page, pgdat);
-
 	return lruvec;
 }
 
@@ -1331,21 +1329,18 @@ static inline struct lruvec *relock_page_lruvec_irqsave(struct page *page,
 	struct pglist_data *pgdat = page_pgdat(page);
 	struct lruvec *lruvec;
 
-	rcu_read_lock();
+	if (!locked_lruvec)
+		goto lock;
+
 	lruvec = mem_cgroup_page_lruvec(page, pgdat);
 
-	if (locked_lruvec == lruvec) {
-		rcu_read_unlock();
+	if (locked_lruvec == lruvec)
 		return lruvec;
-	}
-	rcu_read_unlock();
 
-	if (locked_lruvec)
-		spin_unlock_irqrestore(&locked_lruvec->lru_lock,
-							locked_lruvec->flags);
+	spin_unlock_irqrestore(&locked_lruvec->lru_lock, locked_lruvec->flags);
 
+lock:
 	lruvec = lock_page_lruvec_irqsave(page, pgdat);
-
 	return lruvec;
 }
 
-- 
1.8.3.1

[PATCH v2 7/8] mm/lru: likely enhancement

[Alex Shi]

Use likely() to remove speculations according to pagevec usage mode.

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Chris Down <chris@chrisdown.name>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: cgroups@vger.kernel.org
Cc: linux-mm@kvack.org
---
 include/linux/memcontrol.h | 8 ++++----
 mm/memcontrol.c            | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index f869897a68f0..2a6d7a503452 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1307,12 +1307,12 @@ static inline struct lruvec *relock_page_lruvec_irq(struct page *page,
 	struct pglist_data *pgdat = page_pgdat(page);
 	struct lruvec *lruvec;
 
-	if (!locked_lruvec)
+	if (unlikely(!locked_lruvec))
 		goto lock;
 
 	lruvec = mem_cgroup_page_lruvec(page, pgdat);
 
-	if (locked_lruvec == lruvec)
+	if (likely(locked_lruvec == lruvec))
 		return lruvec;
 
 	spin_unlock_irq(&locked_lruvec->lru_lock);
@@ -1329,12 +1329,12 @@ static inline struct lruvec *relock_page_lruvec_irqsave(struct page *page,
 	struct pglist_data *pgdat = page_pgdat(page);
 	struct lruvec *lruvec;
 
-	if (!locked_lruvec)
+	if (unlikely(!locked_lruvec))
 		goto lock;
 
 	lruvec = mem_cgroup_page_lruvec(page, pgdat);
 
-	if (locked_lruvec == lruvec)
+	if (likely(locked_lruvec == lruvec))
 		return lruvec;
 
 	spin_unlock_irqrestore(&locked_lruvec->lru_lock, locked_lruvec->flags);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d2539bac4677..d95adf49fae3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1273,7 +1273,7 @@ struct lruvec *lock_page_lruvec_irq(struct page *page,
 	spin_lock_irq(&lruvec->lru_lock);
 
 	/* lruvec may changed in commit_charge() */
-	if (lruvec != mem_cgroup_page_lruvec(page, pgdat)) {
+	if (unlikely(lruvec != mem_cgroup_page_lruvec(page, pgdat))) {
 		spin_unlock_irq(&lruvec->lru_lock);
 		goto again;
 	}
@@ -1291,7 +1291,7 @@ struct lruvec *lock_page_lruvec_irqsave(struct page *page,
 	spin_lock_irqsave(&lruvec->lru_lock, lruvec->flags);
 
 	/* lruvec may changed in commit_charge() */
-	if (lruvec != mem_cgroup_page_lruvec(page, pgdat)) {
+	if (unlikely(lruvec != mem_cgroup_page_lruvec(page, pgdat))) {
 		spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->flags);
 		goto again;
 	}
-- 
1.8.3.1

[PATCH v2 8/8] mm/lru: revise the comments of lru_lock

[Alex Shi]

Since we changed the pgdat->lru_lock to lruvec->lru_lock, it's time to
fix the incorrect comments in code. Also fixed some zone->lru_lock comment
error from ancient time. etc.

Originally-from: Hugh Dickins <hughd@google.com>
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Jann Horn <jannh@google.com>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Tobin C. Harding" <tobin@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Dave Chinner <dchinner@redhat.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: cgroups@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
---
 Documentation/admin-guide/cgroup-v1/memcg_test.rst | 15 +++------------
 Documentation/admin-guide/cgroup-v1/memory.rst     |  6 +++---
 Documentation/trace/events-kmem.rst                |  2 +-
 Documentation/vm/unevictable-lru.rst               | 22 ++++++++--------------
 include/linux/mm_types.h                           |  2 +-
 include/linux/mmzone.h                             |  2 +-
 mm/filemap.c                                       |  4 ++--
 mm/rmap.c                                          |  2 +-
 mm/vmscan.c                                        | 12 ++++++++----
 9 files changed, 28 insertions(+), 39 deletions(-)

diff --git a/Documentation/admin-guide/cgroup-v1/memcg_test.rst b/Documentation/admin-guide/cgroup-v1/memcg_test.rst
index 3f7115e07b5d..0b9f91589d3d 100644
--- a/Documentation/admin-guide/cgroup-v1/memcg_test.rst
+++ b/Documentation/admin-guide/cgroup-v1/memcg_test.rst
@@ -133,18 +133,9 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
 
 8. LRU
 ======
-        Each memcg has its own private LRU. Now, its handling is under global
-	VM's control (means that it's handled under global pgdat->lru_lock).
-	Almost all routines around memcg's LRU is called by global LRU's
-	list management functions under pgdat->lru_lock.
-
-	A special function is mem_cgroup_isolate_pages(). This scans
-	memcg's private LRU and call __isolate_lru_page() to extract a page
-	from LRU.
-
-	(By __isolate_lru_page(), the page is removed from both of global and
-	private LRU.)
-
+	Each memcg has its own vector of LRUs (inactive anon, active anon,
+	inactive file, active file, unevictable) of pages from each node,
+	each LRU handled under a single lru_lock for that memcg and node.
 
 9. Typical Tests.
 =================
diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst
index 0ae4f564c2d6..60d97e8b7f3c 100644
--- a/Documentation/admin-guide/cgroup-v1/memory.rst
+++ b/Documentation/admin-guide/cgroup-v1/memory.rst
@@ -297,13 +297,13 @@ When oom event notifier is registered, event will be delivered.
 
    PG_locked.
      mm->page_table_lock
-         pgdat->lru_lock
+         lruvec->lru_lock
 	   lock_page_cgroup.
 
   In many cases, just lock_page_cgroup() is called.
 
-  per-zone-per-cgroup LRU (cgroup's private LRU) is just guarded by
-  pgdat->lru_lock, it has no lock of its own.
+  per-node-per-cgroup LRU (cgroup's private LRU) is just guarded by
+  lruvec->lru_lock, it has no lock of its own.
 
 2.7 Kernel Memory Extension (CONFIG_MEMCG_KMEM)
 -----------------------------------------------
diff --git a/Documentation/trace/events-kmem.rst b/Documentation/trace/events-kmem.rst
index 555484110e36..68fa75247488 100644
--- a/Documentation/trace/events-kmem.rst
+++ b/Documentation/trace/events-kmem.rst
@@ -69,7 +69,7 @@ When pages are freed in batch, the also mm_page_free_batched is triggered.
 Broadly speaking, pages are taken off the LRU lock in bulk and
 freed in batch with a page list. Significant amounts of activity here could
 indicate that the system is under memory pressure and can also indicate
-contention on the zone->lru_lock.
+contention on the lruvec->lru_lock.
 
 4. Per-CPU Allocator Activity
 =============================
diff --git a/Documentation/vm/unevictable-lru.rst b/Documentation/vm/unevictable-lru.rst
index 17d0861b0f1d..0e1490524f53 100644
--- a/Documentation/vm/unevictable-lru.rst
+++ b/Documentation/vm/unevictable-lru.rst
@@ -33,7 +33,7 @@ reclaim in Linux.  The problems have been observed at customer sites on large
 memory x86_64 systems.
 
 To illustrate this with an example, a non-NUMA x86_64 platform with 128GB of
-main memory will have over 32 million 4k pages in a single zone.  When a large
+main memory will have over 32 million 4k pages in a single node.  When a large
 fraction of these pages are not evictable for any reason [see below], vmscan
 will spend a lot of time scanning the LRU lists looking for the small fraction
 of pages that are evictable.  This can result in a situation where all CPUs are
@@ -55,7 +55,7 @@ unevictable, either by definition or by circumstance, in the future.
 The Unevictable Page List
 -------------------------
 
-The Unevictable LRU infrastructure consists of an additional, per-zone, LRU list
+The Unevictable LRU infrastructure consists of an additional, per-node, LRU list
 called the "unevictable" list and an associated page flag, PG_unevictable, to
 indicate that the page is being managed on the unevictable list.
 
@@ -84,15 +84,9 @@ The unevictable list does not differentiate between file-backed and anonymous,
 swap-backed pages.  This differentiation is only important while the pages are,
 in fact, evictable.
 
-The unevictable list benefits from the "arrayification" of the per-zone LRU
+The unevictable list benefits from the "arrayification" of the per-node LRU
 lists and statistics originally proposed and posted by Christoph Lameter.
 
-The unevictable list does not use the LRU pagevec mechanism. Rather,
-unevictable pages are placed directly on the page's zone's unevictable list
-under the zone lru_lock.  This allows us to prevent the stranding of pages on
-the unevictable list when one task has the page isolated from the LRU and other
-tasks are changing the "evictability" state of the page.
-
 
 Memory Control Group Interaction
 --------------------------------
@@ -101,8 +95,8 @@ The unevictable LRU facility interacts with the memory control group [aka
 memory controller; see Documentation/admin-guide/cgroup-v1/memory.rst] by extending the
 lru_list enum.
 
-The memory controller data structure automatically gets a per-zone unevictable
-list as a result of the "arrayification" of the per-zone LRU lists (one per
+The memory controller data structure automatically gets a per-node unevictable
+list as a result of the "arrayification" of the per-node LRU lists (one per
 lru_list enum element).  The memory controller tracks the movement of pages to
 and from the unevictable list.
 
@@ -196,7 +190,7 @@ for the sake of expediency, to leave a unevictable page on one of the regular
 active/inactive LRU lists for vmscan to deal with.  vmscan checks for such
 pages in all of the shrink_{active|inactive|page}_list() functions and will
 "cull" such pages that it encounters: that is, it diverts those pages to the
-unevictable list for the zone being scanned.
+unevictable list for the node being scanned.
 
 There may be situations where a page is mapped into a VM_LOCKED VMA, but the
 page is not marked as PG_mlocked.  Such pages will make it all the way to
@@ -328,7 +322,7 @@ If the page was NOT already mlocked, mlock_vma_page() attempts to isolate the
 page from the LRU, as it is likely on the appropriate active or inactive list
 at that time.  If the isolate_lru_page() succeeds, mlock_vma_page() will put
 back the page - by calling putback_lru_page() - which will notice that the page
-is now mlocked and divert the page to the zone's unevictable list.  If
+is now mlocked and divert the page to the node's unevictable list.  If
 mlock_vma_page() is unable to isolate the page from the LRU, vmscan will handle
 it later if and when it attempts to reclaim the page.
 
@@ -603,7 +597,7 @@ Some examples of these unevictable pages on the LRU lists are:
      unevictable list in mlock_vma_page().
 
 shrink_inactive_list() also diverts any unevictable pages that it finds on the
-inactive lists to the appropriate zone's unevictable list.
+inactive lists to the appropriate node's unevictable list.
 
 shrink_inactive_list() should only see SHM_LOCK'd pages that became SHM_LOCK'd
 after shrink_active_list() had moved them to the inactive list, or pages mapped
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 270aa8fd2800..ff08a6a8145c 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -78,7 +78,7 @@ struct page {
 		struct {	/* Page cache and anonymous pages */
 			/**
 			 * @lru: Pageout list, eg. active_list protected by
-			 * pgdat->lru_lock.  Sometimes used as a generic list
+			 * lruvec->lru_lock.  Sometimes used as a generic list
 			 * by the page owner.
 			 */
 			struct list_head lru;
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 3b6029bcb577..3c7a00016f77 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -159,7 +159,7 @@ static inline bool free_area_empty(struct free_area *area, int migratetype)
 struct pglist_data;
 
 /*
- * zone->lock and the zone lru_lock are two of the hottest locks in the kernel.
+ * zone->lock and the lru_lock are two of the hottest locks in the kernel.
  * So add a wild amount of padding here to ensure that they fall into separate
  * cachelines.  There are very few zone structures in the machine, so space
  * consumption is not a concern here.
diff --git a/mm/filemap.c b/mm/filemap.c
index 85b7d087eb45..c508ae620635 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -101,8 +101,8 @@
  *    ->swap_lock		(try_to_unmap_one)
  *    ->private_lock		(try_to_unmap_one)
  *    ->i_pages lock		(try_to_unmap_one)
- *    ->pgdat->lru_lock		(follow_page->mark_page_accessed)
- *    ->pgdat->lru_lock		(check_pte_range->isolate_lru_page)
+ *    ->lruvec->lru_lock	(follow_page->mark_page_accessed)
+ *    ->lruvec->lru_lock	(check_pte_range->isolate_lru_page)
  *    ->private_lock		(page_remove_rmap->set_page_dirty)
  *    ->i_pages lock		(page_remove_rmap->set_page_dirty)
  *    bdi.wb->list_lock		(page_remove_rmap->set_page_dirty)
diff --git a/mm/rmap.c b/mm/rmap.c
index 0c7b2a9400d4..561c6ad1cbe9 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -27,7 +27,7 @@
  *         mapping->i_mmap_rwsem
  *           anon_vma->rwsem
  *             mm->page_table_lock or pte_lock
- *               pgdat->lru_lock (in mark_page_accessed, isolate_lru_page)
+ *               lruvec->lru_lock (in mark_page_accessed, isolate_lru_page)
  *               swap_lock (in swap_duplicate, swap_info_get)
  *                 mmlist_lock (in mmput, drain_mmlist and others)
  *                 mapping->private_lock (in __set_page_dirty_buffers)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index cbebd9b0b9c8..77948db33c3a 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1661,14 +1661,16 @@ static __always_inline void update_lru_sizes(struct lruvec *lruvec,
 }
 
 /**
- * pgdat->lru_lock is heavily contended.  Some of the functions that
+ * Isolating page from the lruvec to fill in @dst list by nr_to_scan times.
+ *
+ * lruvec->lru_lock is heavily contended.  Some of the functions that
  * shrink the lists perform better by taking out a batch of pages
  * and working on them outside the LRU lock.
  *
  * For pagecache intensive workloads, this function is the hottest
  * spot in the kernel (apart from copy_*_user functions).
  *
- * Appropriate locks must be held before calling this function.
+ * Lru_lock must be held before calling this function.
  *
  * @nr_to_scan:	The number of eligible pages to look through on the list.
  * @lruvec:	The LRU vector to pull pages from.
@@ -1856,14 +1858,16 @@ static int too_many_isolated(struct pglist_data *pgdat, int file,
 
 /*
  * This moves pages from @list to corresponding LRU list.
+ * The pages from @list is out of any lruvec, and in the end list reuses as
+ * pages_to_free list.
  *
  * We move them the other way if the page is referenced by one or more
  * processes, from rmap.
  *
  * If the pages are mostly unmapped, the processing is fast and it is
- * appropriate to hold zone_lru_lock across the whole operation.  But if
+ * appropriate to hold lru_lock across the whole operation.  But if
  * the pages are mapped, the processing is slow (page_referenced()) so we
- * should drop zone_lru_lock around each page.  It's impossible to balance
+ * should drop lru_lock around each page.  It's impossible to balance
  * this, so instead we remove the pages from the LRU while processing them.
  * It is safe to rely on PG_active against the non-LRU pages in here because
  * nobody will play with that bit on a non-LRU page.
-- 
1.8.3.1

Re: [PATCH v2 4/8] mm/lru: only change the lru_lock iff page's lruvec is different

[Matthew Wilcox]

On Tue, Nov 12, 2019 at 10:06:24PM +0800, Alex Shi wrote:
> +/* Don't lock again iff page's lruvec locked */
> +static inline struct lruvec *relock_page_lruvec_irq(struct page *page,
> +					struct lruvec *locked_lruvec)
> +{
> +	struct pglist_data *pgdat = page_pgdat(page);
> +	struct lruvec *lruvec;
> +
> +	rcu_read_lock();
> +	lruvec = mem_cgroup_page_lruvec(page, pgdat);
> +
> +	if (locked_lruvec == lruvec) {
> +		rcu_read_unlock();
> +		return lruvec;
> +	}
> +	rcu_read_unlock();

Why not simply:

	rcu_read_lock();
	lruvec = mem_cgroup_page_lruvec(page, pgdat);
	rcu_read_unlock();

	if (locked_lruvec == lruvec)
		return lruvec;

Also, why are you bothering to re-enable interrupts here?  Surely if
you're holding lock A with interrupts disabled , you can just drop lock A,
acquire lock B and leave the interrupts alone.  That way you only need
one of this variety of function, and not the separate irq/irqsave variants.

Re: [PATCH v2 6/8] mm/lru: remove rcu_read_lock to fix performance regression

[Matthew Wilcox]

On Tue, Nov 12, 2019 at 10:06:26PM +0800, Alex Shi wrote:
> Intel 0day report there are performance regression on this patchset.
> The detailed info points to rcu_read_lock + PROVE_LOCKING which causes
> queued_spin_lock_slowpath waiting too long time to get lock.
> Remove rcu_read_lock is safe here since we had a spinlock hold.

Argh.  You have not sent these patches in a properly reviewable form!
I wasted all that time reviewing the earlier patch in this series only to
find out that you changed it here.  FIX THE PATCH, don't send a fix-patch
on top of it!

> Reported-by: kbuild test robot <lkp@intel.com>
> Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Roman Gushchin <guro@fb.com>
> Cc: Shakeel Butt <shakeelb@google.com>
> Cc: Chris Down <chris@chrisdown.name>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  include/linux/memcontrol.h | 29 ++++++++++++-----------------
>  1 file changed, 12 insertions(+), 17 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 2421b720d272..f869897a68f0 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1307,20 +1307,18 @@ static inline struct lruvec *relock_page_lruvec_irq(struct page *page,
>  	struct pglist_data *pgdat = page_pgdat(page);
>  	struct lruvec *lruvec;
>  
> -	rcu_read_lock();
> +	if (!locked_lruvec)
> +		goto lock;
> +
>  	lruvec = mem_cgroup_page_lruvec(page, pgdat);
>  
> -	if (locked_lruvec == lruvec) {
> -		rcu_read_unlock();
> +	if (locked_lruvec == lruvec)
>  		return lruvec;
> -	}
> -	rcu_read_unlock();
>  
> -	if (locked_lruvec)
> -		spin_unlock_irq(&locked_lruvec->lru_lock);
> +	spin_unlock_irq(&locked_lruvec->lru_lock);
>  
> +lock:
>  	lruvec = lock_page_lruvec_irq(page, pgdat);
> -
>  	return lruvec;
>  }
>  
> @@ -1331,21 +1329,18 @@ static inline struct lruvec *relock_page_lruvec_irqsave(struct page *page,
>  	struct pglist_data *pgdat = page_pgdat(page);
>  	struct lruvec *lruvec;
>  
> -	rcu_read_lock();
> +	if (!locked_lruvec)
> +		goto lock;
> +
>  	lruvec = mem_cgroup_page_lruvec(page, pgdat);
>  
> -	if (locked_lruvec == lruvec) {
> -		rcu_read_unlock();
> +	if (locked_lruvec == lruvec)
>  		return lruvec;
> -	}
> -	rcu_read_unlock();
>  
> -	if (locked_lruvec)
> -		spin_unlock_irqrestore(&locked_lruvec->lru_lock,
> -							locked_lruvec->flags);
> +	spin_unlock_irqrestore(&locked_lruvec->lru_lock, locked_lruvec->flags);
>  
> +lock:
>  	lruvec = lock_page_lruvec_irqsave(page, pgdat);
> -
>  	return lruvec;
>  }
>  
> -- 
> 1.8.3.1
> 
> 

Re: [PATCH v2 4/8] mm/lru: only change the lru_lock iff page's lruvec is different

[Alex Shi]

hi Matthew,

Thanks a lot for comments!

在 2019/11/12 下午10:36, Matthew Wilcox 写道:
> On Tue, Nov 12, 2019 at 10:06:24PM +0800, Alex Shi wrote:
>> +/* Don't lock again iff page's lruvec locked */
>> +static inline struct lruvec *relock_page_lruvec_irq(struct page *page,
>> +					struct lruvec *locked_lruvec)
>> +{
>> +	struct pglist_data *pgdat = page_pgdat(page);
>> +	struct lruvec *lruvec;
>> +
>> +	rcu_read_lock();
>> +	lruvec = mem_cgroup_page_lruvec(page, pgdat);
>> +
>> +	if (locked_lruvec == lruvec) {
>> +		rcu_read_unlock();
>> +		return lruvec;
>> +	}
>> +	rcu_read_unlock();
> 
> Why not simply:
> 
> 	rcu_read_lock();
> 	lruvec = mem_cgroup_page_lruvec(page, pgdat);
> 	rcu_read_unlock();
> 
> 	if (locked_lruvec == lruvec)

The rcu_read_unlock here is for guarding the locked_lruvec/lruvec comparsion.
Otherwise memcg/lruvec maybe changed, like, from memcg migration etc. I guess.
 
> 		return lruvec;
> 
> Also, why are you bothering to re-enable interrupts here?  Surely if
> you're holding lock A with interrupts disabled , you can just drop lock A,
> acquire lock B and leave the interrupts alone.  That way you only need
> one of this variety of function, and not the separate irq/irqsave variants.
> 

Thanks for the suggestion! Yes, if only do re-lock, it's better to leave the irq unchanging. but, when the locked_lruvec is NULL, it become a first time lock which irq or irqsave are different. Thus, in combined function we need a nother parameter to indicate if it do irqsaving. So comparing to a extra/indistinct parameter, I guess 2 inline functions would be a bit more simple/cleary? 

Thanks a lot!
Alex

Re: [PATCH v2 6/8] mm/lru: remove rcu_read_lock to fix performance regression

[Alex Shi]

在 2019/11/12 下午10:38, Matthew Wilcox 写道:
> On Tue, Nov 12, 2019 at 10:06:26PM +0800, Alex Shi wrote:
>> Intel 0day report there are performance regression on this patchset.
>> The detailed info points to rcu_read_lock + PROVE_LOCKING which causes
>> queued_spin_lock_slowpath waiting too long time to get lock.
>> Remove rcu_read_lock is safe here since we had a spinlock hold.
> Argh.  You have not sent these patches in a properly reviewable form!
> I wasted all that time reviewing the earlier patch in this series only to
> find out that you changed it here.  FIX THE PATCH, don't send a fix-patch
> on top of it!
> 

Hi Matthew,

Very sorry for your time! The main reasons I use a separate patch since a, Intel 0day asking me to credit their are founding, and I don't know how to give a clearly/elegant explanation for a non-exist regression in a fixed patch. b, this regression is kindly pretty tricky.  Maybe it's better saying thanks in version change log of cover-letter?

Anyway, Thanks a lot for your review!

Alex

Re: [PATCH v2 6/8] mm/lru: remove rcu_read_lock to fix performance regression

[Mel Gorman]

On Wed, Nov 13, 2019 at 10:40:58AM +0800, Alex Shi wrote:
> 
> 
> ?? 2019/11/12 ????10:38, Matthew Wilcox ????:
> > On Tue, Nov 12, 2019 at 10:06:26PM +0800, Alex Shi wrote:
> >> Intel 0day report there are performance regression on this patchset.
> >> The detailed info points to rcu_read_lock + PROVE_LOCKING which causes
> >> queued_spin_lock_slowpath waiting too long time to get lock.
> >> Remove rcu_read_lock is safe here since we had a spinlock hold.
> > Argh.  You have not sent these patches in a properly reviewable form!
> > I wasted all that time reviewing the earlier patch in this series only to
> > find out that you changed it here.  FIX THE PATCH, don't send a fix-patch
> > on top of it!
> > 
> 
> Hi Matthew,
> 
> Very sorry for your time! The main reasons I use a separate patch since a, Intel 0day asking me to credit their are founding, and I don't know how to give a clearly/elegant explanation for a non-exist regression in a fixed patch. b, this regression is kindly pretty tricky.  Maybe it's better saying thanks in version change log of cover-letter?
> 

Add something like this to the patch

[lkp@intel.com: Fix RCU-related regression reported by LKP robot]
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
...

-- 
Mel Gorman
SUSE Labs

Re: [PATCH v2 4/8] mm/lru: only change the lru_lock iff page's lruvec is different

[Matthew Wilcox]

On Wed, Nov 13, 2019 at 10:26:24AM +0800, Alex Shi wrote:
> 在 2019/11/12 下午10:36, Matthew Wilcox 写道:
> > On Tue, Nov 12, 2019 at 10:06:24PM +0800, Alex Shi wrote:
> >> +/* Don't lock again iff page's lruvec locked */
> >> +static inline struct lruvec *relock_page_lruvec_irq(struct page *page,
> >> +					struct lruvec *locked_lruvec)
> >> +{
> >> +	struct pglist_data *pgdat = page_pgdat(page);
> >> +	struct lruvec *lruvec;
> >> +
> >> +	rcu_read_lock();
> >> +	lruvec = mem_cgroup_page_lruvec(page, pgdat);
> >> +
> >> +	if (locked_lruvec == lruvec) {
> >> +		rcu_read_unlock();
> >> +		return lruvec;
> >> +	}
> >> +	rcu_read_unlock();
> > 
> > Why not simply:
> > 
> > 	rcu_read_lock();
> > 	lruvec = mem_cgroup_page_lruvec(page, pgdat);
> > 	rcu_read_unlock();
> > 
> > 	if (locked_lruvec == lruvec)
> 
> The rcu_read_unlock here is for guarding the locked_lruvec/lruvec comparsion.
> Otherwise memcg/lruvec maybe changed, like, from memcg migration etc. I guess.

How does holding the RCU lock guard the comparison?  You're comparing two
pointers for equality.  Nothing any other CPU can do at this point will
change the results of that comparison.

> > Also, why are you bothering to re-enable interrupts here?  Surely if
> > you're holding lock A with interrupts disabled , you can just drop lock A,
> > acquire lock B and leave the interrupts alone.  That way you only need
> > one of this variety of function, and not the separate irq/irqsave variants.
> > 
> 
> Thanks for the suggestion! Yes, if only do re-lock, it's better to leave the irq unchanging. but, when the locked_lruvec is NULL, it become a first time lock which irq or irqsave are different. Thus, in combined function we need a nother parameter to indicate if it do irqsaving. So comparing to a extra/indistinct parameter, I guess 2 inline functions would be a bit more simple/cleary? 

Ah, right, I missed the "if it's not held" case.

Re: [PATCH v2 4/8] mm/lru: only change the lru_lock iff page's lruvec is different

[Alex Shi]

在 2019/11/13 下午9:45, Matthew Wilcox 写道:
>>> Why not simply:
>>>
>>> 	rcu_read_lock();
>>> 	lruvec = mem_cgroup_page_lruvec(page, pgdat);
>>> 	rcu_read_unlock();
>>>
>>> 	if (locked_lruvec == lruvec)
>> The rcu_read_unlock here is for guarding the locked_lruvec/lruvec comparsion.
>> Otherwise memcg/lruvec maybe changed, like, from memcg migration etc. I guess.
> How does holding the RCU lock guard the comparison?  You're comparing two
> pointers for equality.  Nothing any other CPU can do at this point will
> change the results of that comparison.
> 

Hi Matthew, Thanks for reply!

The reason of guarding lruvec compasion here is a bit undistinct, in fact, it guards the page's memcg from free/migrate etc, since the lruvec is kind of binding to each of memcg. The detailed explanation could be found in lock_page_memcg().

Thanks
Alex

Re: [PATCH v2 6/8] mm/lru: remove rcu_read_lock to fix performance regression

[Alex Shi]

在 2019/11/13 下午7:40, Mel Gorman 写道:
>> Hi Matthew,
>>
>> Very sorry for your time! The main reasons I use a separate patch since a, Intel 0day asking me to credit their are founding, and I don't know how to give a clearly/elegant explanation for a non-exist regression in a fixed patch. b, this regression is kindly pretty tricky.  Maybe it's better saying thanks in version change log of cover-letter?
>>
> Add something like this to the patch
> 
> [lkp@intel.com: Fix RCU-related regression reported by LKP robot]
> Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>

It's a good idea! Thanks a lot, Mel!