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From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
To: Alex Shi <alex.shi@linux.alibaba.com>,
	cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	Mel Gorman <mgorman@techsingularity.net>,
	Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH 03/14] lru/memcg: using per lruvec lock in un/lock_page_lru
Date: Mon, 26 Aug 2019 11:30:28 +0300	[thread overview]
Message-ID: <936eb865-d8da-8e53-3e2b-6858c586aa49@yandex-team.ru> (raw)
In-Reply-To: <1566294517-86418-4-git-send-email-alex.shi@linux.alibaba.com>

On 20/08/2019 12.48, Alex Shi wrote:
> Now we repeatly assign the lruvec->pgdat in memcg. Will remove the
> assignment in lruvec getting function after very points are protected.
> 
> 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: Tejun Heo <tj@kernel.org>
> Cc: cgroups@vger.kernel.org
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> ---
>   mm/memcontrol.c | 12 +++++-------
>   1 file changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index e8a1b0d95ba8..19fd911e8098 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2550,12 +2550,12 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages)
>   static void lock_page_lru(struct page *page, int *isolated)
>   {
>   	pg_data_t *pgdat = page_pgdat(page);
> +	struct lruvec *lruvec = mem_cgroup_page_lruvec(page, pgdat);
>   

What protects lruvec from freeing at this point?
After reading resolving lruvec page could be moved and cgroup deleted.

In this old patches I've used RCU for that: https://lkml.org/lkml/2012/2/20/276
Pointer to lruvec should be resolved under disabled irq.
Not sure this works these days.

> -	spin_lock_irq(&pgdat->lruvec.lru_lock);
> +	spin_lock_irq(&lruvec->lru_lock);
> +	sync_lruvec_pgdat(lruvec, pgdat);
>   	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;
> @@ -2566,16 +2566,14 @@ static void lock_page_lru(struct page *page, int *isolated)
>   static void unlock_page_lru(struct page *page, int isolated)
>   {
>   	pg_data_t *pgdat = page_pgdat(page);
> +	struct lruvec *lruvec = mem_cgroup_page_lruvec(page, pgdat);
>   
>   	if (isolated) {
> -		struct lruvec *lruvec;
> -
> -		lruvec = mem_cgroup_page_lruvec(page, pgdat);
>   		VM_BUG_ON_PAGE(PageLRU(page), page);
>   		SetPageLRU(page);
>   		add_page_to_lru_list(page, lruvec, page_lru(page));
>   	}
> -	spin_unlock_irq(&pgdat->lruvec.lru_lock);
> +	spin_unlock_irq(&lruvec->lru_lock);
>   }
>   
>   static void commit_charge(struct page *page, struct mem_cgroup *memcg,
> 

  reply	other threads:[~2019-08-26  8:30 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-20  9:48 [PATCH 00/14] per memcg lru_lock Alex Shi
2019-08-20  9:48 ` [PATCH 01/14] mm/lru: move pgdat lru_lock into lruvec Alex Shi
2019-08-20 13:40   ` Matthew Wilcox
2019-08-20 14:11     ` Alex Shi
2019-08-20  9:48 ` [PATCH 02/14] lru/memcg: move the lruvec->pgdat sync out lru_lock Alex Shi
2019-08-20  9:48 ` [PATCH 03/14] lru/memcg: using per lruvec lock in un/lock_page_lru Alex Shi
2019-08-26  8:30   ` Konstantin Khlebnikov [this message]
2019-08-26 14:16     ` Alex Shi
2019-08-20  9:48 ` [PATCH 04/14] lru/compaction: use per lruvec lock in isolate_migratepages_block Alex Shi
2019-08-20  9:48 ` [PATCH 05/14] lru/huge_page: use per lruvec lock in __split_huge_page Alex Shi
2019-08-20  9:48 ` [PATCH 06/14] lru/mlock: using per lruvec lock in munlock Alex Shi
2019-08-20  9:48 ` [PATCH 07/14] lru/swap: using per lruvec lock in page_cache_release Alex Shi
2019-08-20  9:48 ` [PATCH 08/14] lru/swap: uer lruvec lock in activate_page Alex Shi
2019-08-20  9:48 ` [PATCH 09/14] lru/swap: uer per lruvec lock in pagevec_lru_move_fn Alex Shi
2019-08-20  9:48 ` [PATCH 10/14] lru/swap: use per lruvec lock in release_pages Alex Shi
2019-08-20  9:48 ` [PATCH 11/14] lru/vmscan: using per lruvec lock in lists shrinking Alex Shi
2019-08-20  9:48 ` [PATCH 12/14] lru/vmscan: use pre lruvec lock in check_move_unevictable_pages Alex Shi
2019-08-20  9:48 ` [PATCH 13/14] lru/vmscan: using per lruvec lru_lock in get_scan_count Alex Shi
2019-08-20  9:48 ` [PATCH 14/14] mm/lru: fix the comments of lru_lock Alex Shi
2019-08-20 14:00   ` Matthew Wilcox
2019-08-20 14:21     ` Alex Shi
2019-08-20 10:45 ` [PATCH 00/14] per memcg lru_lock Michal Hocko
2019-08-20 16:48   ` Shakeel Butt
2019-08-20 18:24     ` Hugh Dickins
2019-08-21  1:21       ` Alex Shi
2019-08-21  2:00       ` Alex Shi
2019-08-24  1:59         ` Hugh Dickins
2019-08-26 14:35           ` Alex Shi
2019-08-21 18:00 ` Daniel Jordan
2019-08-22 11:56   ` Alex Shi
2019-08-22 15:20     ` Daniel Jordan
2019-08-26  8:39       ` Konstantin Khlebnikov
2019-08-26 14:22         ` Alex Shi
2019-08-26 14:25       ` Alex Shi

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