Message-ID: <493DC628.5060900@cn.fujitsu.com>
Date: Tue, 09 Dec 2008 09:13:12 +0800
From: Li Zefan <lizf@cn.fujitsu.com>
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To: Tim Blechmann <tim@klingt.org>
CC: rostedt@goodmis.org, linux-rt-users@vger.kernel.org,
       linux-kernel@vger.kernel.org, Balbir Singh <balbir@linux.vnet.ibm.com>,
       KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [PATCH] [RT] avoid preemption in memory controller code
References: <1228746854-23875-1-git-send-email-tim@klingt.org>
In-Reply-To: <1228746854-23875-1-git-send-email-tim@klingt.org>
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CC: Balbir Singh <balbir@linux.vnet.ibm.com>
CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

Tim Blechmann wrote:
> the lru_lock of struct mem_group_per_zone is used to avoid preemption
> during the __mem_cgroup_stat_add_safe function.
> therefore, a raw_spinlock_t should be used.
> 

FYI, this lru_lock no longer exists in -mm tree. The following patch
removes that lock:

	http://marc.info/?l=linux-mm&m=122665814801979&w=2

> Signed-off-by: Tim Blechmann <tim@klingt.org>
> ---
>  mm/memcontrol.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 517f945..8661732 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -95,9 +95,9 @@ enum mem_cgroup_zstat_index {
>  
>  struct mem_cgroup_per_zone {
>  	/*
> -	 * spin_lock to protect the per cgroup LRU
> +	 * raw_spin_lock to protect the per cgroup LRU
>  	 */
> -	spinlock_t		lru_lock;
> +	raw_spinlock_t		lru_lock;
>  	struct list_head	active_list;
>  	struct list_head	inactive_list;
>  	unsigned long count[NR_MEM_CGROUP_ZSTAT];


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