Re: [PATCH] x86/smpboot: Make logical package management more robust

From: Boris Ostrovsky
Date: Fri Dec 09 2016 - 22:29:38 EST

On 12/09/2016 06:02 PM, Boris Ostrovsky wrote:
On 12/09/2016 05:06 PM, Thomas Gleixner wrote:
On Thu, 8 Dec 2016, Thomas Gleixner wrote:

Boris, can you please verify if that makes the
topology_update_package_map() call which you placed into the Xen cpu
starting code obsolete ?

Will do. I did test your patch but without removing
topology_update_package_map() call. It complained about package IDs
being wrong, but that's expected until I fix Xen part.

Ignore my statement about earlier testing --- it was all on single-node machines.

Something is broken with multi-node on Intel, but failure modes are different. Prior to this patch build_sched_domain() reports an error and pretty soon we crash in scheduler (don't remember off the top of my head). With patch applied I crash mush later, when one of the drivers does kmalloc_node(.., cpu_to_node(cpu)) and cpu_to_node() returns 1, which should never happen ("x86: Booted up 1 node, 32 CPUs" is reported, for example).

2-node AMD box doesn't have these problems.

I haven't upgraded the Intel machine for about a month but this all must have happened in 4.9 timeframe.

So I can't answer your question since we clearly have other problems on Xen. I will be looking into this.