On 23.01.2008 [13:14:26 -0800], Christoph Lameter wrote:

On Wed, 23 Jan 2008, Pekka Enberg wrote:

quoted

I think Mel said that their configuration did work with 2.6.23
although I also wonder how that's possible. AFAIK there has been some
changes in the page allocator that might explain this. That is, if
kmem_getpages() returned pages for memoryless node before, bootstrap
would have worked.

Regular kmem_getpages is called with GFP_THISNODE set. There was some
breakage in 2.6.22 and before with GFP_THISNODE returning pages from
the wrong node if a node had no memory. So it may have worked
accidentally and in an unsafe manner because the pages would have been
associated with the wrong node which could trigger bug ons and locking
troubles.

Right, so it might have functioned before, but the correctness was
wobbly at best... Certainly the memoryless patch series has tightened
that up, but we missed these SLAB issues.

I see that your patch fixed Olaf's machine, Pekka. Nice work on
everyone's part tracking this stuff down.

Thanks,
Nish