linux-kernel - Re: slab: setup allocators earlier in the boot sequence

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Message-Id: <1244796211.30512.32.camel@penberg-laptop>
Date:	Fri, 12 Jun 2009 11:43:31 +0300
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel list <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>, mingo@...e.hu,
	cl@...ux-foundation.org, akpm@...ux-foundation.org, npiggin@...e.de
Subject: Re: slab: setup allocators earlier in the boot sequence

Hi Ben,

On Fri, 2009-06-12 at 18:40 +1000, Benjamin Herrenschmidt wrote:
> On Fri, 2009-06-12 at 10:45 +0300, Pekka Enberg wrote:
> > Hi Ben,
> 
> > The call-sites I fixed up are all boot code AFAICT. And I like I said,
> > we can't really _miss_ any of those places, they must be checking for
> > slab_is_available() _anyway_; otherwise they have no business using
> > kmalloc(). And note: all call-sites that _unconditionally_ use
> > kmalloc(GFP_KERNEL) are safe because they worked before.
> 
> No. The check for slab_is_available() can be levels higher, for example
> the vmalloc case. I'm sure I can find a whole bunch more :-) Besides
> I find the approach fragile, and it will suck for things that can be
> rightfully called also later on.

Yes, you're obviously right. I overlooked the fact that arch code have
their own special slab_is_available() heuristics (yikes!).

But are you happy with the two patches I posted so I can push them to
Linus?

			Pekka

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