Commit fc574c23 authored by Alex Shi's avatar Alex Shi Committed by Linus Torvalds
Browse files

mm/swap.c: serialize memcg changes in pagevec_lru_move_fn 

Hugh Dickins' found a memcg change bug on original version: If we want to
change the pgdat->lru_lock to memcg's lruvec lock, we have to serialize
mem_cgroup_move_account during pagevec_lru_move_fn.  The possible bad
scenario would like:

	cpu 0					cpu 1
lruvec = mem_cgroup_page_lruvec()
					if (!isolate_lru_page())
						mem_cgroup_move_account

spin_lock_irqsave(&lruvec->lru_lock <== wrong lock.

So we need TestClearPageLRU to block isolate_lru_page(), that serializes
the memcg change.  and then removing the PageLRU check in move_fn callee
as the consequence.

__pagevec_lru_add_fn() is different from the others, because the pages it
deals with are, by definition, not yet on the lru.  TestClearPageLRU is
not needed and would not work, so __pagevec_lru_add() goes its own way.

Link: https://lkml.kernel.org/r/1604566549-62481-17-git-send-email-alex.shi@linux.alibaba.com


Reported-by: default avatarHugh Dickins <hughd@google.com>
Signed-off-by: default avatarAlex Shi <alex.shi@linux.alibaba.com>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: "Chen, Rong A" <rong.a.chen@intel.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mika Penttilä <mika.penttila@nextfour.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 9df41314

mm/swap.c

+35 −9
Original line number Diff line number Diff line
@@ -222,8 +222,14 @@ static void pagevec_lru_move_fn(struct pagevec *pvec, 
			spin_lock_irqsave(&pgdat->lru_lock, flags);

		}



		/* block memcg migration during page moving between lru */

		if (!TestClearPageLRU(page))

			continue;



		lruvec = mem_cgroup_page_lruvec(page, pgdat);

		(*move_fn)(page, lruvec);



		SetPageLRU(page);

	}

	if (pgdat)

		spin_unlock_irqrestore(&pgdat->lru_lock, flags);
@@ -233,7 +239,7 @@ static void pagevec_lru_move_fn(struct pagevec *pvec, 


static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec)

{

	if (PageLRU(page) && !PageUnevictable(page)) {

	if (!PageUnevictable(page)) {

		del_page_from_lru_list(page, lruvec, page_lru(page));

		ClearPageActive(page);

		add_page_to_lru_list_tail(page, lruvec, page_lru(page));
@@ -306,7 +312,7 @@ void lru_note_cost_page(struct page *page) 


static void __activate_page(struct page *page, struct lruvec *lruvec)

{

	if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {

	if (!PageActive(page) && !PageUnevictable(page)) {

		int lru = page_lru_base_type(page);

		int nr_pages = thp_nr_pages(page);
@@ -362,6 +368,7 @@ static void activate_page(struct page *page) 


	page = compound_head(page);

	spin_lock_irq(&pgdat->lru_lock);

	if (PageLRU(page))

		__activate_page(page, mem_cgroup_page_lruvec(page, pgdat));

	spin_unlock_irq(&pgdat->lru_lock);

}
@@ -519,9 +526,6 @@ static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec) 
	bool active;

	int nr_pages = thp_nr_pages(page);



	if (!PageLRU(page))

		return;



	if (PageUnevictable(page))

		return;
@@ -562,7 +566,7 @@ static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec) 


static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec)

{

	if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {

	if (PageActive(page) && !PageUnevictable(page)) {

		int lru = page_lru_base_type(page);

		int nr_pages = thp_nr_pages(page);
@@ -579,7 +583,7 @@ static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec) 


static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec)

{

	if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&

	if (PageAnon(page) && PageSwapBacked(page) &&

	    !PageSwapCache(page) && !PageUnevictable(page)) {

		bool active = PageActive(page);

		int nr_pages = thp_nr_pages(page);
@@ -1021,7 +1025,29 @@ static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec) 
 */

void __pagevec_lru_add(struct pagevec *pvec)

{

	pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn);

	int i;

	struct pglist_data *pgdat = NULL;

	struct lruvec *lruvec;

	unsigned long flags = 0;



	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 = mem_cgroup_page_lruvec(page, pgdat);

		__pagevec_lru_add_fn(page, lruvec);

	}

	if (pgdat)

		spin_unlock_irqrestore(&pgdat->lru_lock, flags);

	release_pages(pvec->pages, pvec->nr);

	pagevec_reinit(pvec);

}



/**

CRA Git | Maintained and supported by SUSTech CRA and CCSE