On Tue, 16 Jan 2018, Yu, Fenghua wrote:
> > From: Thomas Gleixner [mailto:t...@linutronix.de]
> Is this a Haswell specific issue?
> 
> I run the following test forever without issue on Broadwell and 4.15.0-rc6 
> with rdt mounted:
> for ((;;)) do
>         for ((i=1;i<88;i++)) do
>                 echo 0 >/sys/devices/system/cpu/cpu$i/online
>         done
>         echo "online cpus:"
>         grep processor /proc/cpuinfo |wc
>         for ((i=1;i<88;i++)) do
>                 echo 1 >/sys/devices/system/cpu/cpu$i/online
>         done
>         echo "online cpus:"
>         grep processor /proc/cpuinfo|wc
> done
> 
> I'm finding a Haswell to reproduce the issue.

Come on. This is crystal clear from the KASAN trace. And the fix is
simple enough.

You simply do not run into it because on your machine

    is_llc_occupancy_enabled() is false...

Thanks,

        tglx
        
8<--------------------  

diff --git a/arch/x86/kernel/cpu/intel_rdt.c b/arch/x86/kernel/cpu/intel_rdt.c
index 88dcf8479013..99442370de40 100644
--- a/arch/x86/kernel/cpu/intel_rdt.c
+++ b/arch/x86/kernel/cpu/intel_rdt.c
@@ -525,10 +525,6 @@ static void domain_remove_cpu(int cpu, struct rdt_resource 
*r)
                 */
                if (static_branch_unlikely(&rdt_mon_enable_key))
                        rmdir_mondata_subdir_allrdtgrp(r, d->id);
-               kfree(d->ctrl_val);
-               kfree(d->rmid_busy_llc);
-               kfree(d->mbm_total);
-               kfree(d->mbm_local);
                list_del(&d->list);
                if (is_mbm_enabled())
                        cancel_delayed_work(&d->mbm_over);
@@ -545,6 +541,10 @@ static void domain_remove_cpu(int cpu, struct rdt_resource 
*r)
                        cancel_delayed_work(&d->cqm_limbo);
                }
 
+               kfree(d->ctrl_val);
+               kfree(d->rmid_busy_llc);
+               kfree(d->mbm_total);
+               kfree(d->mbm_local);
                kfree(d);
                return;
        }

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You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1733662

Title:
  System hang with Linux kernel due to mainline commit 24247aeeabe

Status in linux package in Ubuntu:
  In Progress
Status in linux-hwe package in Ubuntu:
  Confirmed
Status in linux source package in Artful:
  In Progress
Status in linux-hwe source package in Artful:
  Confirmed
Status in linux source package in Bionic:
  In Progress
Status in linux-hwe source package in Bionic:
  Confirmed

Bug description:
  In doing Ubuntu 17.10 regression testing, we've encountered one
  computer (boldore, a Cisco UCS C240 M4 [VIC]), that hangs about one in
  four times when running our cpu_offlining test. This test attempts to
  take all the CPU cores offline except one, then brings them back
  online again. This test ran successfully on boldore with previous
  releases, but with 17.10, the system sometimes (about one in four
  runs) hangs. Reverting to Ubuntu 16.04.3, I found no problems; but
  when I upgraded the 16.04.3 installation to linux-
  image-4.13.0-16-generic, the problem appeared again, so I'm confident
  this is a problem with the kernel. I'm attaching two files, dmesg-
  output-4.10.txt and dmesg-output-4.13.txt, which show the dmesg output
  that appears when running the cpu_offlining test with 4.10.0-38 and
  4.13.0-16 kernels, respectively; the system hung on the 4.13 run. (I
  was running "dmesg -w" in a second SSH login; the files are cut-and-
  pasted from that.)

  I initiated this bug report from an Ubuntu 16.04.3 installation
  running a 4.10 kernel; but as I said, this applies to the 4.13 kernel.

  ProblemType: Bug
  DistroRelease: Ubuntu 16.04
  Package: linux-image-4.10.0-38-generic 4.10.0-38.42~16.04.1
  ProcVersionSignature: User Name 4.10.0-38.42~16.04.1-generic 4.10.17
  Uname: Linux 4.10.0-38-generic x86_64
  ApportVersion: 2.20.1-0ubuntu2.10
  Architecture: amd64
  Date: Tue Nov 21 17:36:06 2017
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: linux-hwe
  UpgradeStatus: No upgrade log present (probably fresh install)

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