linux-kernel - Re: [PATCH 3/6] staging: android/lowmemorykiller: Don't grab tasklist

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Date:	Wed, 8 Feb 2012 16:32:16 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Anton Vorontsov <anton.vorontsov@...aro.org>
Cc:	Greg KH <gregkh@...uxfoundation.org>,
	Arve Hjønnevåg <arve@...roid.com>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	San Mehat <san@...gle.com>, Colin Cross <ccross@...roid.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, kernel-team@...roid.com,
	linaro-kernel@...ts.linaro.org
Subject: Re: [PATCH 3/6] staging: android/lowmemorykiller: Don't grab
	tasklist_lock

On 02/06, Anton Vorontsov wrote:
>
> Grabbing tasklist_lock has its disadvantages, i.e. it blocks
> process creation and destruction. If there are lots of processes,
> blocking doesn't sound as a great idea.
>
> For LMK, it is sufficient to surround tasks list traverse with
> rcu_read_{,un}lock().
>
> From now on using force_sig() is not safe, as it can race with an
> already exiting task, so we use send_sig() now. As a downside, it
> won't kill PID namespace init processes, but that's not what we
> want anyway.

Reviewed-by: Oleg Nesterov <oleg@...hat.com>

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