[PATCH v2] arch_numa: Restore nid checks before registering a memblock with a node

[Mike Rapoport]

On Sun, Dec 01, 2024 at 07:49:44PM +0000, Marc Zyngier wrote:
> Hi Mike,
> 
> On Sun, 01 Dec 2024 19:32:22 +0000,
> Mike Rapoport <rppt at kernel.org> wrote:
> > 
> > Hi Marc,
> > 
> > On Sun, Dec 01, 2024 at 09:27:02AM +0000, Marc Zyngier wrote:
> > > Commit 767507654c22 ("arch_numa: switch over to numa_memblks")
> > > significantly cleaned up the NUMA registration code, but also
> > > dropped a significant check that was refusing to accept to
> > > configure a memblock with an invalid nid.
> > 
> > ... 
> >  
> > > while previous kernel versions were able to recognise how brain-damaged
> > > the machine is, and only build a fake node.
> > > 
> > > Use the memblock_validate_numa_coverage() helper to restore some sanity
> > > and a "working" system.
> > > 
> > > Fixes: 767507654c22 ("arch_numa: switch over to numa_memblks")
> > > Suggested-by: Mike Rapoport <rppt at kernel.org>
> > > Signed-off-by: Marc Zyngier <maz at kernel.org>
> > > Cc: Catalin Marinas <catalin.marinas at arm.com>
> > > Cc: Will Deacon <will at kernel.org>
> > > Cc: Zi Yan <ziy at nvidia.com>
> > > Cc: Dan Williams <dan.j.williams at intel.com>
> > > Cc: David Hildenbrand <david at redhat.com>
> > > Cc: Andrew Morton <akpm at linux-foundation.org>
> > > Cc: stable at vger.kernel.org
> > > ---
> > >  drivers/base/arch_numa.c | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > > 
> > > diff --git a/drivers/base/arch_numa.c b/drivers/base/arch_numa.c
> > > index e187016764265..c63a72a1fed64 100644
> > > --- a/drivers/base/arch_numa.c
> > > +++ b/drivers/base/arch_numa.c
> > > @@ -208,6 +208,10 @@ static int __init numa_register_nodes(void)
> > >  {
> > >  	int nid;
> > >  
> > > +	/* Check the validity of the memblock/node mapping */
> > > +	if (!memblock_validate_numa_coverage(1))
> > 
> > I've changed this to memblock_validate_numa_coverage(0) and applied along
> > with my patch that changed memblock_validate_numa_coverage() to work with
> > 0:
> > 
> > https://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock.git/log/?h=thunderx-fix
> > 
> > Can you please verify that it works on your "quality hardware"?
> 
> Commit 427c6179e159b in your tree still has memblock_validate_numa_coverage(1).
> Forgot to push out the updated version?

Argh, indeed. 
 
> Flipping this to 0 locally, I have verified that this still allows the
> old thing to trudge along:
> 
> root at duodenum:~# uname -a
> Linux duodenum 6.12.0-12115-g427c6179e159-dirty #3896 SMP PREEMPT Sun Dec  1 19:43:13 GMT 2024 aarch64

Thanks for testing!
 
> Thanks again,
> 
> 	M.

-- 
Sincerely yours,
Mike.