Re: [PATCH] x86/smp: Fix __max_logical_packages value setup

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] x86/smp: Fix __max_logical_packages value setup
Date	2016-08-11 14:50 +0200
Message-ID	<s4XAS-3T5-25@gated-at.bofh.it> (permalink)
References	(1 earlier) <s4GJH-j6-13@gated-at.bofh.it> <s4GJH-j6-15@gated-at.bofh.it> <s4GJH-j6-17@gated-at.bofh.it> <s4GJH-j6-19@gated-at.bofh.it> <s4GJH-j6-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Wed, Aug 10, 2016 at 06:14:18PM +0200, Jiri Olsa wrote:
> > Maybe one nit, the variable is no longer used for a max, so maybe rename
> > it too?

> diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
> index cf75871d2f81..c28010088651 100644
> --- a/arch/x86/include/asm/topology.h
> +++ b/arch/x86/include/asm/topology.h
> @@ -118,8 +118,8 @@ extern const struct cpumask *cpu_coregroup_mask(int cpu);
>  #define topology_core_cpumask(cpu)		(per_cpu(cpu_core_map, cpu))
>  #define topology_sibling_cpumask(cpu)		(per_cpu(cpu_sibling_map, cpu))
>  
> -extern unsigned int __max_logical_packages;
> -#define topology_max_packages()			(__max_logical_packages)
> +extern unsigned int logical_packages;
> +#define topology_max_packages()			(logical_packages)
>  
>  extern int __max_smt_threads;
>  

Aaahh, I missed this bit yesterday..

Imagine a machine with physical hotplug, where we boot with half the
sockets populated (say 2), then topology_max_packages() will return 2
when we run the uncore driver init.

That driver will allocate resources based on 2.

Then we physically hotplug the remaining sockets (another 2), which will
result in topology_max_packages() to now return 4.

When we run the cpuhotplug hook, it will try and access resources based
on 4, which were not allocated.

blergh..

Thread

[RFC][PATCH] x86/smp: Fix __max_logical_packages value setup Jiri Olsa <jolsa@redhat.com> - 2016-08-03 18:30 +0200
  Re: [RFC][PATCH] x86/smp: Fix __max_logical_packages value setup Jiri Olsa <jolsa@redhat.com> - 2016-08-10 20:50 +0200
    [PATCH] x86/smp: Fix __max_logical_packages value setup Jiri Olsa <jolsa@redhat.com> - 2016-08-10 20:50 +0200
      Re: [PATCH] x86/smp: Fix __max_logical_packages value setup Peter Zijlstra <peterz@infradead.org> - 2016-08-11 14:50 +0200
        Re: [PATCH] x86/smp: Fix __max_logical_packages value setup Jiri Olsa <jolsa@redhat.com> - 2016-08-11 15:10 +0200
          Re: [PATCH] x86/smp: Fix __max_logical_packages value setup Peter Zijlstra <peterz@infradead.org> - 2016-08-11 15:50 +0200
            Re: [PATCH] x86/smp: Fix __max_logical_packages value setup Jiri Olsa <jolsa@redhat.com> - 2016-08-12 14:30 +0200
              Re: [PATCH] x86/smp: Fix __max_logical_packages value setup Jiri Olsa <jolsa@redhat.com> - 2016-08-12 15:20 +0200
              Re: [PATCH] x86/smp: Fix __max_logical_packages value setup Peter Zijlstra <peterz@infradead.org> - 2016-08-15 11:10 +0200
                [PATCH] x86/smp: Fix __max_logical_packages value setup Jiri Olsa <jolsa@redhat.com> - 2016-08-15 12:20 +0200
                Re: [PATCH] x86/smp: Fix __max_logical_packages value setup Prarit Bhargava <prarit@redhat.com> - 2016-08-15 13:50 +0200
                [tip:x86/urgent] x86/smp: Fix __max_logical_packages value setup tip-bot for Jiri Olsa <tipbot@zytor.com> - 2016-08-18 13:00 +0200
    Re: [RFC][PATCH] x86/smp: Fix __max_logical_packages value setup Jiri Olsa <jolsa@redhat.com> - 2016-08-10 21:10 +0200
      Re: [RFC][PATCH] x86/smp: Fix __max_logical_packages value setup Peter Zijlstra <peterz@infradead.org> - 2016-08-10 21:20 +0200
  Re: [RFC][PATCH] x86/smp: Fix __max_logical_packages value setup Peter Zijlstra <peterz@infradead.org> - 2016-08-10 21:20 +0200
  Re: [RFC][PATCH] x86/smp: Fix __max_logical_packages value setup Jiri Olsa <jolsa@redhat.com> - 2016-08-10 22:40 +0200

csiph-web