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

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Date:	Sat, 13 Jun 2009 07:42:36 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Pekka Enberg <penberg@...helsinki.fi>, Ingo Molnar <mingo@...e.hu>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org, npiggin@...e.de,
	cl@...ux-foundation.org, torvalds@...ux-foundation.org
Subject: Re: [PATCH v2] slab,slub: ignore __GFP_WAIT if we're booting or 
 suspending

On Fri, 2009-06-12 at 08:30 -0700, Andrew Morton wrote:
> On Fri, 12 Jun 2009 14:34:00 +0300 Pekka Enberg <penberg@...helsinki.fi> 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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