Re: linux-next: build failure after merge of the final tree (slabtree related)

[Christoph Lameter]

On Wed, 25 Aug 2010, Pekka Enberg wrote:

> On 8/25/10 11:18 AM, Tejun Heo wrote:
> > Hello,
> >
> > On 08/24/2010 08:53 PM, Christoph Lameter wrote:
> > > > [    0.000000] Kernel panic - not syncing: Cannot create slab kmem_cache
> > > > size=232 realsize=256 order=0 offset=0 flags=42000
> > >
> > > alloc per cpu result in kmalloc which fails.
> > >
> > > Tejon: Is there some way we could get a reserved per cpu area under UP
> > > instead of fallback to slab allocations during bootup?
> >
> > Eh... nasty.  Maybe we can create a alloc_percpu_early() function
> > which doesn't allow freeing of allocate memory and just redirect to
> > bootmem on UP?
>
> Yeah, I was thinking about that too.

Another solution is to allocate an order 1 (compound) page for each early
cache. Then resize the kmalloc array after everything is up. kfree() will
then redirect to the page allocator.

But this is a slab allocator specific solution.

We now have the situation that alloc_percpu can only be used on early boot
on SMP machines. A general solution would be better I think.

If the early alloc_percpu stuff would work consistently then it could also
be used to avoid the boot_pageset in the page allocator f.e.

Can we just get rid of the special UP case and just run the percpu
subsystem even for UP?

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/