Re: [PATCH v2] slab,slub: ignore __GFP_WAIT if we're booting or suspending

From: Benjamin Herrenschmidt
Date: Fri Jun 12 2009 - 17:43:21 EST


On Fri, 2009-06-12 at 08:30 -0700, Andrew Morton wrote:
> On Fri, 12 Jun 2009 14:34:00 +0300 Pekka Enberg <penberg@xxxxxxxxxxxxxx> wrote:
>
> > +static gfp_t slab_gfp_mask __read_mostly = __GFP_BITS_MASK & ~__GFP_WAIT;
>
> It'd be safer and saner to disable __GFP_FS and __GFP_IO as well.

Right. That's what my original patch does in fact. I also re-enabled
them all together but in that case, it might be better to re-enable FS
and IO later, I'll let experts decide.

> Having either of those flags set without __GFP_WAIT is a somewhat
> self-contradictory thing and there might be code under reclaim which
> assumes that __GFP_FS|__GFP_IO implies __GFP_WAIT.
>
> <wonders why mempool_alloc() didn't clear __GFP_FS>

Cheers,
Ben.

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