Re: 2.6.26: x86/kernel/pci_dma.c: gfp |= __GFP_NORETRY ?

From: Andi Kleen
Date: Sun May 25 2008 - 17:15:44 EST


On Sun, May 25, 2008 at 08:55:32PM +0100, Alan Cox wrote:
> On Sun, 25 May 2008 18:35:39 +0200
> Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
>
> > > So how about linux-2.6.26-gfp-no-oom.patch (see previous mail) for
> > > 2.6.26
> >
> > Changing the gfp once globally like you did is not right, because
> > the different fallback cases have to be handled differently
> > (see the different cases I discussed in my earlier mail)
> >
> > Especially the 16MB zone allocation should never trigger the OOM killer.
>
> That depends how much memory you have.

No it doesn't because the lower zone protection basically never puts
anything that is not GFP_DMA into the 16MB zone.

Just check yourself on your machine using sysrq.

That was one of the motivations behind the mask allocator design.

-Andi
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