linux-kernel - Re: select(0, ..) is valid ?

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Message-ID: <29495f1d0705211821r4200a1fft2b5c07a62b0620b1@mail.gmail.com>
Date:	Mon, 21 May 2007 18:21:18 -0700
From:	"Nish Aravamudan" <nish.aravamudan@...il.com>
To:	"Andi Kleen" <ak@...e.de>
Cc:	"Anton Blanchard" <anton@...ba.org>,
	"Hugh Dickins" <hugh@...itas.com>,
	"Christoph Lameter" <clameter@....com>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Badari Pulavarty" <pbadari@...ibm.com>, netdev@...r.kernel.org,
	lkml <linux-kernel@...r.kernel.org>, sfr@...b.auug.org.au
Subject: Re: select(0, ..) is valid ?

On 5/18/07, Andi Kleen <ak@...e.de> wrote:
> On Wednesday 16 May 2007 17:37, Anton Blanchard wrote:
> > Hi Hugh,
> >
> > > It's interesting that compat_core_sys_select() shows this kmalloc(0)
> > > failure but core_sys_select() does not.  That's because core_sys_select()
> > > avoids kmalloc by using a buffer on the stack for small allocations (and
> > > 0 sure is small).  Shouldn't compat_core_sys_select() do just the same?
> > > Or is SLUB going to be so efficient that doing so is a waste of time?
> >
> > Nice catch, the original optimisation from Andi is:
> >
> > http://git.kernel.org/git-new/?p=linux/kernel/git/torvalds/linux-2.6.git;a=
> >commit;h=70674f95c0a2ea694d5c39f4e514f538a09be36f
> >
> > And I think it makes sense for the compat code to do it too.
>
> Yes agreed. I just forgot the copy'n'pasted code when doing the original
> change.

Is this headed upstream? It's causing some noise on test.kernel.org
now that SLAB is also warning about kmalloc(0).

Thanks,
Nish
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