SRU request submitted for Artful and Bionic.
https://lists.ubuntu.com/archives/kernel-team/2018-January/089403.html
** Description changed:
- 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.)
+ == 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 <[email protected]>
+ 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
+ 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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https://bugs.launchpad.net/bugs/1733662
Title:
System hang with Linux kernel due to mainline commit 24247aeeabe
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