From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Oliver Neukum <oliver@neukum.org>
Subject: Re: [RFC][PATCH] PM: Force GFP_NOIO during suspend/resume (was: Re: [linux-pm] Memory allocations in .suspend became very unreliable)
Date: Sun, 17 Jan 2010 14:36:29 +0100
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Cc: Maxim Levitsky <maximlevitsky@gmail.com>,
       linux-pm@lists.linux-foundation.org,
       LKML <linux-kernel@vger.kernel.org>, "linux-mm" <linux-mm@kvack.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       Benjamin Herrenschmidt <benh@kernel.crashing.org>
References: <1263549544.3112.10.camel@maxim-laptop> <201001170224.36267.oliver@neukum.org> <201001171427.27954.rjw@sisk.pl>
In-Reply-To: <201001171427.27954.rjw@sisk.pl>
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On Sunday 17 January 2010, Rafael J. Wysocki wrote:
> On Sunday 17 January 2010, Oliver Neukum wrote:
> > Am Sonntag, 17. Januar 2010 01:38:37 schrieb Rafael J. Wysocki:
> > > > Now having said that, we've been considering a change that will turn all
> > > > GFP_KERNEL allocations into GFP_NOIO during suspend/resume, so perhaps I'll
> > > > prepare a patch to do that and let's see what people think.
> > > 
> > > If I didn't confuse anything (which is likely, because it's a bit late here
> > > now), the patch below should do the trick.  I have only checked that it doesn't
> > > break compilation, so please take it with a grain of salt.
> > > 
> > > Comments welcome.
> > 
> > I think this is a bad idea as it makes the mm subsystem behave differently
> > in the runtime and in the whole system cases.
> 
> s/runtime/suspend/ ?
> 
> Yes it will, but why exactly shouldn't it?  System suspend/resume _is_ a
> special situation anyway.

Moreover, as the Maxim's report indicates, the mm subsystem already behaves
differently during suspend/resume and this behavior is erroneous, because it
causes the system to hang.

Rafael
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