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Subject: Re: [patch for-3.7] mm, mempolicy: fix printing stack contents in
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From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 26 Oct 2012 10:48:43 +0200
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To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>, Sasha Levin <levinsasha928@gmail.com>, Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>, Dave Jones <davej@redhat.com>, Andrew Morton <akpm@linux-foundation.org>, KOSAKI Motohiro <kosaki.motohiro@gmail.com>, bhutchings@solarflare.com, Konstantin Khlebnikov <khlebnikov@openvz.org>, Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>, Hugh Dickins <hughd@google.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, linux-kernel@vger.kernel.org, linux-mm@kvack.org

On Thu, 2012-10-25 at 16:09 -0700, Linus Torvalds wrote:
> On Thu, Oct 25, 2012 at 7:39 AM, Peter Zijlstra <peterz@infradead.org> wr=
ote:
> >
> > So I think the below should work, we hold the spinlock over both rb-tre=
e
> > modification as sp free, this makes mpol_shared_policy_lookup() which
> > returns the policy with an incremented refcount work with just the
> > spinlock.
> >
> > Comments?
>=20
> Looks reasonable, if annoyingly complex for something that shouldn't
> be important enough for this. Oh well.

I agree with that.. Its just that when doing numa placement one needs to
respect the pre-existing placement constraints. I've not seen a way
around this.

> However, please check me on this: the need for this is only for
> linux-next right now, correct? All the current users in my tree are ok
> with just the mutex, no?

Yes, the need comes from the numa stuff and I'll stick this patch in
there.

I completely missed Mel's patch turning it into a mutex, but I guess
that's what -next is for :-).

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