linux-kernel - Re: [GIT PULL v2] Early SLAB fixes for 2.6.31

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Message-Id: <1245081420.23207.58.camel@penberg-laptop>
Date:	Mon, 15 Jun 2009 18:57:00 +0300
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	Christoph Lameter <cl@...ux-foundation.org>
Cc:	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, kamezawa.hiroyu@...fujitsu.com,
	lizf@...fujitsu.com, mingo@...e.hu, npiggin@...e.de,
	yinghai@...nel.org, benh@...nel.crashing.org
Subject: Re: [GIT PULL v2] Early SLAB fixes for 2.6.31

On Mon, 2009-06-15 at 11:51 -0400, Christoph Lameter wrote:
> On Mon, 15 Jun 2009, Pekka Enberg wrote:
> 
> > > OK, I can clean this up, no problem.
> >
> > Actually, there's a slight complication here. If I push gfp mask to
> > __might_sleep(), lockdep_trace_alloc() and so on, the mask is
> > effective _everywhere_ even outside of slab. Yes, it makes sense if we
> > push the masking right down to the page allocator but I wonder if
> > that's something we want to do at this point?
> 
> __might_sleep just should not trigger right? The mask does not need to be
> passed. __might_sleep may be called uselessly during bootup if __GFP_WAIT
> is set. But it should not trigger any output. Look at the initial
> statements of __might_sleep: They are already prepared to simply return in
> the early boot case.

Oh, yeah, you're right about __might_sleep() so we can just ignore that.

But we still have bit of a problem for should_failslab() and
__lockdep_trace_alloc(). We might be able to deal with the former by
adding system_state check but for the latter, we need to mask the gfp
flags. Hmm.

			Pekka

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