On 10/20/2017 05:03 AM, Thomas Gleixner wrote:
> On Thu, 19 Oct 2017, Prarit Bhargava wrote:
>> static void remove_siblinginfo(int cpu)
>> {
>> - int sibling;
>> + int phys_pkg_id, sibling;
>> struct cpuinfo_x86 *c = &cpu_data(cpu);
>>
>> for_each_cpu(sibling, topology_core_cpumask(cpu)) {
>> @@ -1529,6 +1526,12 @@ static void remove_siblinginfo(int cpu)
>> cpumask_clear(topology_core_cpumask(cpu));
>> c->phys_proc_id = 0;
>> c->cpu_core_id = 0;
>> +
>> + phys_pkg_id = c->phys_pkg_id;
>> + c->phys_pkg_id = U16_MAX;
>
> This leaves c->logical_proc_set = 1, which is inconsistent at best. I have
> no idea why we need this logical_proc_set flag at all.
>
>> + if (topology_phys_to_logical_pkg(phys_pkg_id) < 0)
>> + logical_packages--;
>
> Now this has another issue. Depending on hotplug ordering the logical
> package association can change across hotplug operations. I don't know it
> that's an issue, but this needs to be analyzed before we merge that.
>
Thanks for making me look at this Thomas.
Andi, it looks like this is unfortunately an issue. I have a reworked
patchset that fixes by dynamically allocating a u16
logical_to_physical_package array that
a) maps the logical to physical package IDs,
b) is dynamically sized to the value of logical_packages, and,
c) is of size logical_packages (not MAX_APICS)
This will resolve the problem that Thomas has pointed out, and it
would address the issue of wasting memory.
I'm waiting for a 4S & 8S system to test the LTP hotplug tests on
and then I'll post. Andi, I'll send it to you in private email for
a quick review.
P.
> Thanks,
>
> tglx
>
>
