linux-kernel - Re: [PATCH v4 08/12] Inject asynchronous page fault into a guest if page is swapped out.

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Message-ID: <20100709155047.GC11885@redhat.com>
Date:	Fri, 9 Jul 2010 18:50:47 +0300
From:	Gleb Natapov <gleb@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Marcelo Tosatti <mtosatti@...hat.com>, kvm@...r.kernel.org,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org, avi@...hat.com,
	mingo@...e.hu, tglx@...utronix.de, hpa@...or.com, riel@...hat.com,
	cl@...ux-foundation.org
Subject: Re: [PATCH v4 08/12] Inject asynchronous page fault into a guest
 if page is swapped out.

On Thu, Jul 08, 2010 at 08:10:31PM +0200, Peter Zijlstra wrote:
> On Thu, 2010-07-08 at 20:09 +0200, Peter Zijlstra wrote:
> > On Thu, 2010-07-08 at 21:05 +0300, Gleb Natapov wrote:
> > > > > +   /* do alloc atomic since if we are going to sleep anyway we
> > > > > +      may as well sleep faulting in page */
> > > > > +   work = kmem_cache_zalloc(async_pf_cache, GFP_ATOMIC);
> > > > > +   if (!work)
> > > > > +           return 0;
> > > > 
> > > > GFP_KERNEL is fine for this context.
> > > But it can sleep, no? The comment explains why I don't want to sleep
> > > here. 
> > 
> > In that case, use 0, no use wasting __GFP_HIGH on something that doesn't
> > actually need it.
> 
> Ah, I just saw we have GFP_NOWAIT for that.
Indeed. Will use GFP_NOWAIT.

--
			Gleb.
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