** Changed in: linux (Ubuntu Artful)
Status: Fix Committed => In Progress
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https://bugs.launchpad.net/bugs/1733662
Title:
System hang with Linux kernel due to mainline commit 24247aeeabe
Status in linux package in Ubuntu:
Fix Committed
Status in linux source package in Artful:
In Progress
Status in linux source package in Bionic:
Fix Committed
Bug description:
== SRU Justification ==
The following mainline commit introduced a regression in v4.14-rc1:
24247aeeabe9 ("x86/intel_rdt/cqm: Improve limbo list processing")
This commit made it's way into Artful via Launchpad bug 1591609 as Artful
commit
ac2fc5adab0f4b.
This bug was causing regression tests to hang about one in four
times when running cpu_offlining tests.
This patch to fix this regression was just submitted to mainline, so it is
also
needed in Bionic.
== Fix ==
commit d47924417319e3b6a728c0b690f183e75bc2a702
Author: Thomas Gleixner <t...@linutronix.de>
Date: Tue Jan 16 19:59:59 2018 +0100
x86/intel_rdt/cqm: Prevent use after free
== Regression Potential ==
Low. This patch fixes a current regression that is a use after free.
### Original 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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