Re: 2.6.22 -mm merge plans: slub

[Hugh Dickins <hugh@veritas.com>]

On Thu, 3 May 2007, Andrew Morton wrote:
> On Thu, 3 May 2007 09:46:32 +0100 (BST) Hugh Dickins <hugh@veritas.com> wrote:
> > On Thu, 3 May 2007, Andrew Morton wrote:
> > > On Wed, 2 May 2007 10:25:47 -0700 (PDT) Christoph Lameter <clameter@sgi.com> wrote:
> > > 
> > > > +config ARCH_USES_SLAB_PAGE_STRUCT
> > > > +	bool
> > > > +	default y
> > > > +	depends on SPLIT_PTLOCK_CPUS <= NR_CPUS
> > > > +
> > > 
> > > That all seems to work as intended.
> > > 
> > > However with NR_CPUS=8 SPLIT_PTLOCK_CPUS=4, enabling SLUB=y crashes the
> > > machine early in boot.  
> > 
> > I thought that if that worked as intended, you wouldn't even
> > get the chance to choose SLUB=y?  That was how it was working
> > for me (but I realize I didn't try more than make oldconfig).
> > 
> > That sounds like what happens when SLUB's pagestruct use meets
> > SPLIT_PTLOCK's pagestruct use.  Does your .config really show
> > CONFIG_SLUB=y together with CONFIG_ARCH_USES_SLAB_PAGE_STRUCT=y?
> 
> Nope.
> 
> g5:/usr/src/25> grep SLUB .config
> CONFIG_SLUB=y
> g5:/usr/src/25> grep SLAB .config
> # CONFIG_SLAB is not set
> g5:/usr/src/25> grep CPUS .config
> CONFIG_NR_CPUS=8
> # CONFIG_CPUSETS is not set
> # CONFIG_IRQ_ALL_CPUS is not set
> CONFIG_SPLIT_PTLOCK_CPUS=4
> 
> It's in http://userweb.kernel.org/~akpm/config-g5.txt

Seems we're all wrong in thinking Christoph's Kconfiggery worked
as intended: maybe it just works some of the time.  I'm not going
to hazard a guess as to how to fix it up, will resume looking at
the powerpc's quicklist potential later.

Hugh
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