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From: Christoph Hellwig <hch@infradead.org>
To: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Paul Jackson <pj@sgi.com>,
	menage@google.com, akpm@linux-foundation.org, dev@sw.ru,
	xemul@sw.ru, serue@us.ibm.com, ebiederm@xmission.com,
	haveblue@us.ibm.com, svaidy@linux.vnet.ibm.com,
	balbir@in.ibm.com, ckrm-tech@lists.sourceforge.net,
	linux-kernel@vger.kernel.org, rohitseth@google.com,
	mbligh@google.com, containers@lists.osdl.org, devel@openvz.org
Subject: Re: [PATCH 0/9] Containers (V9): Generic Process Containers
Date: Mon, 30 Apr 2007 18:23:52 +0100	[thread overview]
Message-ID: <20070430172352.GA8567@infradead.org> (raw)
In-Reply-To: <20070430171225.GH24350@in.ibm.com>

On Mon, Apr 30, 2007 at 10:42:25PM +0530, Srivatsa Vaddagiri wrote:
> On Sun, Apr 29, 2007 at 02:37:21AM -0700, Paul Jackson wrote:
> > It builds and boots and mounts the cpuset file system ok.
> > But trying to write the 'mems' file hangs the system hard.
> 
> Basically we are attempting a read_lock(&tasklist_lock) in
> container_task_count() after taking write_lock_irq(&tasklist_lock) in
> update_nodemask()!
> 
> This patch seems to fix the prb for me:
> 
> 
> Fix write_lock() followed by read_lock() bug by introducing a 2nd
> argument to be passed into container_task_count. Other choice is to
> introduce a lock and unlocked versions of container_task_count() ..
> 
> Signed-off-by : Srivatsa Vaddagiri <vatsa@in.ibm.com>

> -int container_task_count(const struct container *cont) {
> +int container_task_count(const struct container *cont, int take_lock) {
>  	int count = 0;
>  	struct task_struct *g, *p;
>  	struct container_subsys_state *css;
>  	int subsys_id;
>  	get_first_subsys(cont, &css, &subsys_id);
>  
> -	read_lock(&tasklist_lock);
> +	if (take_lock)
> +		read_lock(&tasklist_lock);
>  	do_each_thread(g, p) {
>  		if (task_subsys_state(p, subsys_id) == css)
>  			count ++;
>  	} while_each_thread(g, p);
> -	read_unlock(&tasklist_lock);
> +	if (take_lock)
> +		read_unlock(&tasklist_lock);
>  	return count;

Umm, no - please naje two versions with and without the lock.  Also
Please fix up the codingstyle, the { belongs onto a line of it's own.


  parent reply	other threads:[~2007-04-30 17:25 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-27 10:46 menage
2007-04-27 10:46 ` [PATCH 1/9] Containers (V9): Basic container framework menage
2007-04-29  3:12   ` [ckrm-tech] " Paul Jackson
2007-05-01 17:40   ` Balbir Singh
2007-05-01 17:46     ` Paul Menage
2007-05-01 18:40     ` [ckrm-tech] " Paul Jackson
2007-05-02  3:44       ` Balbir Singh
2007-05-02  6:12         ` Paul Jackson
2007-05-10  4:09           ` Balbir Singh
2007-05-10  4:47             ` Paul Jackson
2007-05-10  4:49               ` Balbir Singh
2007-04-27 10:46 ` [PATCH 2/9] Containers (V9): Example CPU accounting subsystem menage
2007-05-01 17:52   ` Balbir Singh
2007-04-27 10:46 ` [PATCH 3/9] Containers (V9): Add tasks file interface menage
2007-05-01 18:12   ` Balbir Singh
2007-05-01 20:37     ` [ckrm-tech] " Paul Menage
2007-05-02  3:25       ` Srivatsa Vaddagiri
2007-05-02  3:25         ` Paul Menage
2007-05-02  3:46           ` Srivatsa Vaddagiri
2007-05-08 14:51           ` Balbir Singh
2007-05-10 21:21             ` Paul Menage
2007-05-11  2:31               ` Balbir Singh
2007-05-02  3:58       ` Balbir Singh
2007-04-27 10:46 ` [PATCH 4/9] Containers (V9): Add fork/exit hooks menage
2007-04-27 10:46 ` [PATCH 5/9] Containers (V9): Add container_clone() interface menage
2007-04-27 10:46 ` [PATCH 6/9] Containers (V9): Add procfs interface menage
2007-04-27 10:46 ` [PATCH 7/9] Containers (V9): Make cpusets a client of containers menage
2007-04-27 10:46 ` [PATCH 8/9] Containers (V9): Share css_group arrays between tasks with same container memberships menage
2007-04-27 10:46 ` [PATCH 9/9] Containers (V9): Simple debug info subsystem menage
2007-04-29  1:47 ` [PATCH 0/9] Containers (V9): Generic Process Containers Paul Jackson
2007-04-29  9:37 ` Paul Jackson
2007-04-30 17:12   ` Srivatsa Vaddagiri
2007-04-30 17:09     ` Paul Menage
2007-04-30 18:06       ` Srivatsa Vaddagiri
2007-04-30 17:23     ` Christoph Hellwig [this message]
2007-04-30 18:16       ` [ckrm-tech] " Srivatsa Vaddagiri

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