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Date: Tue, 5 May 2009 15:37:39 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: rientjes@google.com, fengguang.wu@intel.com,
       linux-pm@lists.linux-foundation.org, pavel@ucw.cz,
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       alan-jenkins@tuffmail.co.uk, linux-kernel@vger.kernel.org,
       kernel-testers@vger.kernel.org
Subject: Re: [PATCH 1/5] mm: Add __GFP_NO_OOM_KILL flag
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On Wed, 6 May 2009 00:19:35 +0200
"Rafael J. Wysocki" <rjw@sisk.pl> wrote:

> > > +			&& !processes_are_frozen()) {
> > >  		if (!try_set_zone_oom(zonelist, gfp_mask)) {
> > >  			schedule_timeout_uninterruptible(1);
> > >  			goto restart;
> > 
> > Cool, that looks like the semantics of __GFP_NO_OOM_KILL without requiring 
> > a new gfp flag.  Thanks.
> 
> Well, you're welcome.
> 
> BTW, I think that Andrew was actually right when he asked if I checked whether
> the existing __GFP_NORETRY would work as-is for __GFP_FS set and
> __GFP_NORETRY unset.  Namely, in that case we never reach the code before
> nopage: that checks __GFP_NORETRY, do we?
> 
> So I think we shouldn't modify the 'else if' condition above and check for
> !processes_are_frozen() at the beginning of the block below.

Confused.

I'm suspecting that hibernation can allocate its pages with
__GFP_FS|__GFP_WAIT|__GFP_NORETRY|__GFP_NOWARN, and the page allocator
will dtrt: no oom-killings.

In which case, processes_are_frozen() is not needed at all?