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Date: Tue, 12 May 2009 15:05:46 +0200
From: Nick Piggin <npiggin@suse.de>
To: Jens Axboe <jens.axboe@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       David Rientjes <rientjes@google.com>, mel@csn.ul.ie,
       a.p.zijlstra@chello.nl, cl@linux-foundation.org,
       dave@linux.vnet.ibm.com, linux-kernel@vger.kernel.org,
       Divy Le Ray <divy@chelsio.com>
Subject: Re: [patch -mmotm] mm: invoke oom killer for __GFP_NOFAIL
Message-ID: <20090512130546.GA15793@wotan.suse.de>
References: <alpine.DEB.2.00.0905091544470.6884@chino.kir.corp.google.com> <20090511134038.5cf1ad3b.akpm@linux-foundation.org> <20090512124201.GO4140@kernel.dk>
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On Tue, May 12, 2009 at 02:42:02PM +0200, Jens Axboe wrote:
> On Mon, May 11 2009, Andrew Morton wrote:
> > On Sat, 9 May 2009 15:46:39 -0700 (PDT)
> > David Rientjes <rientjes@google.com> wrote:
> > 
> > > The oom killer must be invoked regardless of the order if the allocation
> > > is __GFP_NOFAIL, otherwise it will loop forever when reclaim fails to
> > > free some memory.
> > 
> > Sigh.  We're supposed to be deleting __GFP_NOFAIL.  I added it as a way
> > of easily finding lame error-handling-challenged callers which need to
> > be fixed up.  So of course we went and added lots more callers.
> > 
> > y:/usr/src/linux-2.6.30-rc5> grep -rl GFP_NOFAIL . 
> > ./fs/bio-integrity.c

This is no good either, it seems to be in the bio submission path.

It needs a mempool or something.

It has a dead code "fallback" that returns an error, but I suspect that's
not really acceptable.