linux-kernel - [PATCH 0/3 v3] x86/smpboot: Fix panic in __max_logical

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Date:   Thu, 19 Oct 2017 11:57:10 -0400
From:   Prarit Bhargava <prarit@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Prarit Bhargava <prarit@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Piotr Luc <piotr.luc@...el.com>,
        Kan Liang <kan.liang@...el.com>, Borislav Petkov <bp@...e.de>,
        Stephane Eranian <eranian@...gle.com>,
        Arvind Yadav <arvind.yadav.cs@...il.com>,
        Andy Lutomirski <luto@...nel.org>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        He Chen <he.chen@...ux.intel.com>,
        Mathias Krause <minipli@...glemail.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: [PATCH 0/3 v3] x86/smpboot: Fix panic in __max_logical_packages estimate

A system booted with a small number of cores enabled per package
panics because the estimate of __max_logical_packages is too low.
This occurs when the total number of active cores across all packages
is less than the maximum core count for a single package.

Andi noted that the logical_packages calculation wastes 128k on 64-bit
x86 systems and posted patches to fix the allocation.  I have put my
fix on top of those patches.

Here's an example of the panic:

     smpboot: Booting Node   1, Processors  #1 OK
     smpboot: Package 1 of CPU 1 exceeds BIOS package data 1.
     ------------[ cut here ]------------
     kernel BUG at arch/x86/kernel/cpu/common.c:1087!
     invalid opcode: 0000 [#1] SMP
     Modules linked in:
     CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.14.0-rc2+ #4

This was tested by dropping the number of active cores across
all packages to reproduce the bug above.  Additional testing included
2 socket and 4 socket systems and hotplugging entire sockets in different
order.

Signed-off-by: Prarit Bhargava <prarit@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Piotr Luc <piotr.luc@...el.com>
Cc: Kan Liang <kan.liang@...el.com>
Cc: Borislav Petkov <bp@...e.de>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Arvind Yadav <arvind.yadav.cs@...il.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Christian Borntraeger <borntraeger@...ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: He Chen <he.chen@...ux.intel.com>
Cc: Mathias Krause <minipli@...glemail.com>
Cc: Tim Chen <tim.c.chen@...ux.intel.com>
Cc: Vitaly Kuznetsov <vkuznets@...hat.com>

Andi Kleen (2):
  perf/x86/intel/uncore: Cache logical pkg id in uncore driver
  x86/topology: Avoid wasting 128k for package id array

Prarit Bhargava (1):
  x86/smpboot: Fix __max_logical_packages estimate

 arch/x86/events/intel/uncore.c       |   1 +
 arch/x86/events/intel/uncore.h       |   1 +
 arch/x86/events/intel/uncore_snbep.c |   2 +-
 arch/x86/include/asm/processor.h     |   6 +-
 arch/x86/kernel/smpboot.c            | 124 +++++++++++++----------------------
 5 files changed, 53 insertions(+), 81 deletions(-)

-- 
2.15.0.rc0.39.g2f0e14e64