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

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Date:	Wed, 8 Feb 2012 16:56:10 -0800
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Anton Vorontsov <anton.vorontsov@...aro.org>
Cc:	Oleg Nesterov <oleg@...hat.com>,
	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 Mon, Feb 06, 2012 at 08:42:15PM +0400, Anton Vorontsov wrote:
> On Mon, Feb 06, 2012 at 08:36:49AM -0800, Greg KH wrote:
> > On Mon, Feb 06, 2012 at 08:29:41PM +0400, 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.
> > > 
> > > Suggested-by: Oleg Nesterov <oleg@...hat.com>
> > > Signed-off-by: Anton Vorontsov <anton.vorontsov@...aro.org>
> > 
> > Are these last 4 patches independant of the first 2 and can be taken
> > through the staging tree now?
> 
> Yep, without the first two there is just a bit of sparse warnings.
> Not a big deal.

Ok, I'll take the last 4, the first 2 needs to go through some other
tree (-mm?)

thanks,

greg k-h
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