| 2021-03-26 11:29:22 |
bugproxy |
bug |
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added bug |
| 2021-03-26 11:29:24 |
bugproxy |
tags |
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architecture-s39064 bugnameltc-192225 severity-high targetmilestone-inin2104 |
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| 2021-03-26 11:29:25 |
bugproxy |
ubuntu: assignee |
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Skipper Bug Screeners (skipper-screen-team) |
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| 2021-03-26 11:29:30 |
bugproxy |
affects |
ubuntu |
linux (Ubuntu) |
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| 2021-03-26 11:59:31 |
Frank Heimes |
bug task added |
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ubuntu-z-systems |
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| 2021-03-26 12:00:33 |
Frank Heimes |
ubuntu-z-systems: assignee |
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Skipper Bug Screeners (skipper-screen-team) |
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| 2021-03-26 12:01:13 |
Frank Heimes |
nominated for series |
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Ubuntu Focal |
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| 2021-03-26 12:01:13 |
Frank Heimes |
bug task added |
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linux (Ubuntu Focal) |
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| 2021-03-26 12:01:13 |
Frank Heimes |
nominated for series |
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Ubuntu Hirsute |
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| 2021-03-26 12:01:13 |
Frank Heimes |
bug task added |
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linux (Ubuntu Hirsute) |
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| 2021-03-26 12:01:13 |
Frank Heimes |
nominated for series |
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Ubuntu Groovy |
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| 2021-03-26 12:01:13 |
Frank Heimes |
bug task added |
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linux (Ubuntu Groovy) |
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| 2021-03-26 12:01:24 |
Frank Heimes |
ubuntu-z-systems: importance |
Undecided |
High |
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| 2021-03-26 12:01:28 |
Frank Heimes |
ubuntu-z-systems: status |
New |
Triaged |
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| 2021-03-26 12:01:32 |
Frank Heimes |
linux (Ubuntu Hirsute): assignee |
Skipper Bug Screeners (skipper-screen-team) |
Frank Heimes (fheimes) |
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| 2021-03-29 16:20:43 |
Frank Heimes |
description |
Description: s390/vtime: fix increased steal time accounting
Symptom: Increased steal time values.
Problem: Commit 152e9b8676c6e ("s390/vtime: steal time exponential
moving average") inadvertently changed the input value for
account_steal_time() from "cputime_to_nsecs(steal)" to just
"steal", resulting in broken increased steal time accounting.
Solution: Fix this by changing it back to "cputime_to_nsecs(steal)".
Reproduction: -
Upstream-ID: d54cb7d54877d529bc1e0e1f47a3dd082f73add3
Stable tagged : kernel 5.1.
Therefore only to be applyable for focal, groovy, hirsuite.
Due to stable tag integration , only for integration checking.. |
SRU Justification:
==================
[Impact]
* The reported steal time on s390x is erroneously increasing and therefore broken.
* This problem got introduced with commit 152e9b8676c6e
("s390/vtime: steal time exponential moving average") - upstream with v5.1
[Fix]
* d54cb7d54877d529bc1e0e1f47a3dd082f73add3 d54cb7d54877 "s390/vtime: fix increased steal time accounting"
[Test Case]
* An IBM Z or LinuxONE systems, installed with Ubuntu Server 20.04, 20.10 and 21.04 on LPAR, are needed.
* The system needs to be configured as KVM host with one or more KVM guests.
* Now put significant workload on the guest(s), so that the hypervisor starts to 'steal time'.
This can be best forced by having only very limited CPU resources for the hypervisor itself.
* Start monitoring the steal time, that is reported at /proc/stat,
but can be more easily verified with tools like vmstat or even top.
* If the steal time starts ever growing (exponentially), the situation is broken.
* In case the steal time stays relatively constant,
or grows only very limited after a ramp up phase of some minutes,
or just oscillates around a certain value, a fixed/patched kernel is in use.
[Regression Potential]
* The patch only changes the single line that calculates: account_steal_time
* In case the account_steal_time calculation is still broken after the modification,
the steal time is just again not reported correctly on s390x,
but maybe in a different way (rather than exponentially growing).
* But it will not further harm virtualization on s390x systems.
* The modification is very limited with that one line change.
* The commit got upstream accepted with 5.12-rc4.
[Other]
* Since the patch is needed for kernel higher than 5.1 and got upstream accepted with 5.12-rc4,
hirsute, groovy and focal are affected.
* The upstream commit can be cleanly cherry-picked from all three affected Ubuntu releases.
__________
Description: s390/vtime: fix increased steal time accounting
Symptom: Increased steal time values.
Problem: Commit 152e9b8676c6e ("s390/vtime: steal time exponential
moving average") inadvertently changed the input value for
account_steal_time() from "cputime_to_nsecs(steal)" to just
"steal", resulting in broken increased steal time accounting.
Solution: Fix this by changing it back to "cputime_to_nsecs(steal)".
Reproduction: -
Upstream-ID: d54cb7d54877d529bc1e0e1f47a3dd082f73add3
Stable tagged : kernel 5.1.
Therefore only to be applyable for focal, groovy, hirsuite.
Due to stable tag integration , only for integration checking.. |
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| 2021-03-29 16:21:19 |
Frank Heimes |
linux (Ubuntu Focal): assignee |
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Canonical Kernel Team (canonical-kernel-team) |
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| 2021-03-29 16:21:32 |
Frank Heimes |
linux (Ubuntu Groovy): assignee |
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Canonical Kernel Team (canonical-kernel-team) |
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| 2021-03-29 16:21:41 |
Frank Heimes |
linux (Ubuntu Hirsute): assignee |
Frank Heimes (fheimes) |
Canonical Kernel Team (canonical-kernel-team) |
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| 2021-03-29 16:21:46 |
Frank Heimes |
linux (Ubuntu Focal): importance |
Undecided |
High |
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| 2021-03-29 16:21:49 |
Frank Heimes |
linux (Ubuntu Groovy): importance |
Undecided |
High |
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| 2021-03-29 16:21:53 |
Frank Heimes |
linux (Ubuntu Hirsute): importance |
Undecided |
High |
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| 2021-03-29 16:21:58 |
Frank Heimes |
linux (Ubuntu Hirsute): status |
New |
In Progress |
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| 2021-03-29 16:22:01 |
Frank Heimes |
linux (Ubuntu Groovy): status |
New |
In Progress |
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| 2021-03-29 16:22:07 |
Frank Heimes |
linux (Ubuntu Focal): status |
New |
In Progress |
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| 2021-04-02 22:36:04 |
Kelsey Steele |
linux (Ubuntu Focal): status |
In Progress |
Fix Committed |
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| 2021-04-02 22:36:07 |
Kelsey Steele |
linux (Ubuntu Groovy): status |
In Progress |
Fix Committed |
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| 2021-04-03 10:14:22 |
Frank Heimes |
ubuntu-z-systems: status |
Triaged |
Fix Committed |
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| 2021-04-14 15:41:59 |
Frank Heimes |
linux (Ubuntu Hirsute): status |
In Progress |
Fix Released |
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| 2021-04-19 15:33:29 |
Ubuntu Kernel Bot |
tags |
architecture-s39064 bugnameltc-192225 severity-high targetmilestone-inin2104 |
architecture-s39064 bugnameltc-192225 severity-high targetmilestone-inin2104 verification-needed-focal |
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| 2021-04-20 13:59:20 |
Ubuntu Kernel Bot |
tags |
architecture-s39064 bugnameltc-192225 severity-high targetmilestone-inin2104 verification-needed-focal |
architecture-s39064 bugnameltc-192225 severity-high targetmilestone-inin2104 verification-needed-focal verification-needed-groovy |
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| 2021-04-28 13:18:30 |
Frank Heimes |
summary |
[UBUNUT 21.04] s390/vtime: fix increased steal time accounting |
[Ubuntu 21.04] s390/vtime: fix increased steal time accounting |
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| 2021-04-28 13:56:23 |
Frank Heimes |
tags |
architecture-s39064 bugnameltc-192225 severity-high targetmilestone-inin2104 verification-needed-focal verification-needed-groovy |
architecture-s39064 bugnameltc-192225 severity-high targetmilestone-inin2104 verification-done-focal verification-done-groovy |
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| 2021-05-10 19:50:21 |
Launchpad Janitor |
linux (Ubuntu Focal): status |
Fix Committed |
Fix Released |
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| 2021-05-10 19:50:21 |
Launchpad Janitor |
cve linked |
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2021-29650 |
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| 2021-05-11 17:04:11 |
Launchpad Janitor |
linux (Ubuntu Groovy): status |
Fix Committed |
Fix Released |
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| 2021-05-11 17:04:11 |
Launchpad Janitor |
cve linked |
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2021-3489 |
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| 2021-05-11 17:04:11 |
Launchpad Janitor |
cve linked |
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2021-3490 |
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| 2021-05-11 17:04:11 |
Launchpad Janitor |
cve linked |
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2021-3491 |
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| 2021-05-11 17:15:36 |
Frank Heimes |
ubuntu-z-systems: status |
Fix Committed |
Fix Released |
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