From: Vladimir Davydov <vdavydov@virtuozzo.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH] memcg: put soft limit reclaim out of way if the excess tree is empty
Date: Mon, 1 Aug 2016 16:57:57 +0300 [thread overview]
Message-ID: <20160801135757.GB19395@esperanza> (raw)
In-Reply-To: <1470045621-14335-1-git-send-email-mhocko@kernel.org>
On Mon, Aug 01, 2016 at 12:00:21PM +0200, Michal Hocko wrote:
...
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index c265212bec8c..eb7e39c2d948 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2543,6 +2543,11 @@ static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
> return ret;
> }
>
> +static inline bool soft_limit_tree_empty(struct mem_cgroup_tree_per_node *mctz)
> +{
> + return rb_last(&mctz->rb_root) == NULL;
> +}
> +
I don't think traversing rb tree as rb_last() does w/o holding the lock
is a good idea. Why is RB_EMPTY_ROOT() insufficient here?
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WARNING: multiple messages have this Message-ID (diff)
From: Vladimir Davydov <vdavydov@virtuozzo.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>, <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH] memcg: put soft limit reclaim out of way if the excess tree is empty
Date: Mon, 1 Aug 2016 16:57:57 +0300 [thread overview]
Message-ID: <20160801135757.GB19395@esperanza> (raw)
In-Reply-To: <1470045621-14335-1-git-send-email-mhocko@kernel.org>
On Mon, Aug 01, 2016 at 12:00:21PM +0200, Michal Hocko wrote:
...
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index c265212bec8c..eb7e39c2d948 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2543,6 +2543,11 @@ static int mem_cgroup_resize_memsw_limit(struct mem_cgroup *memcg,
> return ret;
> }
>
> +static inline bool soft_limit_tree_empty(struct mem_cgroup_tree_per_node *mctz)
> +{
> + return rb_last(&mctz->rb_root) == NULL;
> +}
> +
I don't think traversing rb tree as rb_last() does w/o holding the lock
is a good idea. Why is RB_EMPTY_ROOT() insufficient here?
next prev parent reply other threads:[~2016-08-01 13:58 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-01 10:00 [PATCH] memcg: put soft limit reclaim out of way if the excess tree is empty Michal Hocko
2016-08-01 10:00 ` Michal Hocko
2016-08-01 13:57 ` Vladimir Davydov [this message]
2016-08-01 13:57 ` Vladimir Davydov
2016-08-01 14:12 ` Michal Hocko
2016-08-01 14:12 ` Michal Hocko
2016-08-01 14:26 ` Vladimir Davydov
2016-08-01 14:26 ` Vladimir Davydov
2016-08-01 15:03 ` Johannes Weiner
2016-08-01 15:03 ` Johannes Weiner
2016-08-01 15:24 ` Michal Hocko
2016-08-01 15:24 ` Michal Hocko
2016-08-01 17:17 ` Johannes Weiner
2016-08-01 17:17 ` Johannes Weiner
2016-08-01 17:39 ` Michal Hocko
2016-08-01 17:39 ` Michal Hocko
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