| 2018-04-06 06:50:10 |
bugproxy |
bug |
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added bug |
| 2018-04-06 06:50:12 |
bugproxy |
tags |
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architecture-s39064 bugnameltc-166421 severity-high targetmilestone-inin16041 |
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| 2018-04-06 06:50:13 |
bugproxy |
attachment added |
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s390: fix rwlock implementation https://bugs.launchpad.net/bugs/1761674/+attachment/5103572/+files/rwlock.patch |
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| 2018-04-06 06:50:14 |
bugproxy |
ubuntu: assignee |
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Skipper Bug Screeners (skipper-screen-team) |
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| 2018-04-06 06:50:18 |
bugproxy |
affects |
ubuntu |
linux (Ubuntu) |
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| 2018-04-06 06:52:50 |
Frank Heimes |
bug task added |
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ubuntu-z-systems |
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| 2018-04-06 06:53:12 |
Frank Heimes |
ubuntu-z-systems: status |
New |
Triaged |
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| 2018-04-06 06:53:15 |
Frank Heimes |
ubuntu-z-systems: importance |
Undecided |
High |
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| 2018-04-06 06:53:30 |
Frank Heimes |
ubuntu-z-systems: assignee |
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Canonical Kernel Team (canonical-kernel-team) |
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| 2018-04-06 18:03:04 |
Joseph Salisbury |
linux (Ubuntu): importance |
Undecided |
High |
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| 2018-04-06 18:03:17 |
Joseph Salisbury |
linux (Ubuntu): assignee |
Skipper Bug Screeners (skipper-screen-team) |
Canonical Kernel Team (canonical-kernel-team) |
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| 2018-04-06 18:03:22 |
Joseph Salisbury |
linux (Ubuntu): status |
New |
Triaged |
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| 2018-04-06 18:08:53 |
Joseph Salisbury |
tags |
architecture-s39064 bugnameltc-166421 severity-high targetmilestone-inin16041 |
architecture-s39064 bugnameltc-166421 kernel-da-key severity-high targetmilestone-inin16041 |
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| 2018-04-09 14:11:44 |
Joseph Salisbury |
nominated for series |
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Ubuntu Artful |
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| 2018-04-09 14:11:44 |
Joseph Salisbury |
bug task added |
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linux (Ubuntu Artful) |
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| 2018-04-09 14:11:44 |
Joseph Salisbury |
nominated for series |
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Ubuntu Bionic |
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| 2018-04-09 14:11:44 |
Joseph Salisbury |
bug task added |
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linux (Ubuntu Bionic) |
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| 2018-04-09 14:11:44 |
Joseph Salisbury |
nominated for series |
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Ubuntu Xenial |
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| 2018-04-09 14:11:44 |
Joseph Salisbury |
bug task added |
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linux (Ubuntu Xenial) |
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| 2018-04-09 14:11:50 |
Joseph Salisbury |
linux (Ubuntu Xenial): status |
New |
Triaged |
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| 2018-04-09 14:11:53 |
Joseph Salisbury |
linux (Ubuntu Artful): status |
New |
Triaged |
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| 2018-04-09 14:11:57 |
Joseph Salisbury |
linux (Ubuntu Artful): importance |
Undecided |
High |
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| 2018-04-09 14:11:59 |
Joseph Salisbury |
linux (Ubuntu Xenial): importance |
Undecided |
High |
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| 2018-04-09 14:23:24 |
Joseph Salisbury |
linux (Ubuntu Bionic): status |
Triaged |
Fix Released |
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| 2018-04-09 14:23:29 |
Joseph Salisbury |
linux (Ubuntu Artful): status |
Triaged |
In Progress |
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| 2018-04-09 14:23:32 |
Joseph Salisbury |
linux (Ubuntu Xenial): status |
Triaged |
In Progress |
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| 2018-04-09 14:23:43 |
Joseph Salisbury |
linux (Ubuntu Artful): assignee |
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Joseph Salisbury (jsalisbury) |
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| 2018-04-09 14:23:46 |
Joseph Salisbury |
linux (Ubuntu Xenial): assignee |
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Joseph Salisbury (jsalisbury) |
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| 2018-04-09 19:15:51 |
Joseph Salisbury |
linux (Ubuntu Artful): status |
In Progress |
Incomplete |
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| 2018-04-09 20:01:53 |
Frank Heimes |
ubuntu-z-systems: status |
Triaged |
In Progress |
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| 2018-04-14 10:50:15 |
bugproxy |
tags |
architecture-s39064 bugnameltc-166421 kernel-da-key severity-high targetmilestone-inin16041 |
architecture-s39064 targetmilestone-inin16041 |
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| 2018-04-14 10:50:19 |
bugproxy |
attachment added |
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Linux kernel v4.13 patch https://bugs.launchpad.net/bugs/1761674/+attachment/5115180/+files/rwlock-4.13.patch |
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| 2018-04-16 17:59:30 |
Joseph Salisbury |
linux (Ubuntu Artful): status |
Incomplete |
In Progress |
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| 2018-05-04 09:00:40 |
bugproxy |
tags |
architecture-s39064 targetmilestone-inin16041 |
architecture-s39064 bugnameltc-166421 severity-high targetmilestone-inin16041 |
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| 2018-05-07 22:05:31 |
Joseph Salisbury |
description |
Description: kernel: fix rwlock implementation
Symptom: Kernel hangs, due to deadlock on an rwlock.
Problem: With upstream commit 94232a4332de ("s390/rwlock: improve writer
fairness") rwlock writer fairness was supposed to be
implemented. If a writer tries to take an rwlock it sets
unconditionally the writer bit within the lock word and waits
until all readers have released the lock. This however can lead
to a deadlock since rwlocks can be taken recursively by readers.
If e.g. CPU 0 holds the lock as a reader, and CPU 1 wants to
write-lock the lock, then CPU 1 sets the writer bit and
afterwards busy waits for CPU 0 to release the lock. If now CPU 0
tries to read-lock the lock again (recursively) it will also busy
wait until CPU 1 removes the writer bit, which will never happen,
since it waits for the first reader on CPU 0 to release the lock.
Solution: Revert the rwlock writer fairness semantics again. |
== SRU Justification ==
IBM reported this bug due to a regression introduced by mainline commit
94232a4332de. IBM has requested this SAUCE backport to resolve this
regression in Artful and Xenial.
With Bionic and v4.15, the rwlock code has been rewritten. See upstream gitcommit:
eb3b7b848fb3 ("s390/rwlock: introduce rwlock wait queueing").
Since the upstream code has been rewritten there also won't be an upstream
git commit id available which contains the attached fix.
== Fix ==
UBUNTU: SAUCE: (no-up) s390: fix rwlock implementation
== Regression Potential ==
Low. The backport was written and tested by IBM. It is specific to s390.
== Test Case ==
A test kernel was built with this patch and tested by the original bug reporter.
The bug reporter states the test kernel resolved the bug.
Description: kernel: fix rwlock implementation
Symptom: Kernel hangs, due to deadlock on an rwlock.
Problem: With upstream commit 94232a4332de ("s390/rwlock: improve writer
fairness") rwlock writer fairness was supposed to be
implemented. If a writer tries to take an rwlock it sets
unconditionally the writer bit within the lock word and waits
until all readers have released the lock. This however can lead
to a deadlock since rwlocks can be taken recursively by readers.
If e.g. CPU 0 holds the lock as a reader, and CPU 1 wants to
write-lock the lock, then CPU 1 sets the writer bit and
afterwards busy waits for CPU 0 to release the lock. If now CPU 0
tries to read-lock the lock again (recursively) it will also busy
wait until CPU 1 removes the writer bit, which will never happen,
since it waits for the first reader on CPU 0 to release the lock.
Solution: Revert the rwlock writer fairness semantics again. |
|
| 2018-05-23 15:19:23 |
Stefan Bader |
linux (Ubuntu Xenial): status |
In Progress |
Fix Committed |
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| 2018-05-23 15:53:07 |
Stefan Bader |
linux (Ubuntu Artful): status |
In Progress |
Fix Committed |
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| 2018-05-23 16:20:03 |
Frank Heimes |
ubuntu-z-systems: status |
In Progress |
Fix Committed |
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| 2018-05-25 01:02:43 |
Brad Figg |
tags |
architecture-s39064 bugnameltc-166421 severity-high targetmilestone-inin16041 |
architecture-s39064 bugnameltc-166421 severity-high targetmilestone-inin16041 verification-needed-artful |
|
| 2018-05-28 14:03:58 |
Brad Figg |
tags |
architecture-s39064 bugnameltc-166421 severity-high targetmilestone-inin16041 verification-needed-artful |
architecture-s39064 bugnameltc-166421 severity-high targetmilestone-inin16041 verification-needed-artful verification-needed-xenial |
|
| 2018-06-07 17:52:14 |
Frank Heimes |
tags |
architecture-s39064 bugnameltc-166421 severity-high targetmilestone-inin16041 verification-needed-artful verification-needed-xenial |
architecture-s39064 bugnameltc-166421 severity-high targetmilestone-inin16041 verification-done-artful verification-done-xenial |
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| 2018-06-11 15:09:13 |
Launchpad Janitor |
linux (Ubuntu Xenial): status |
Fix Committed |
Fix Released |
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| 2018-06-11 15:09:13 |
Launchpad Janitor |
cve linked |
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2017-5715 |
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| 2018-06-11 15:09:13 |
Launchpad Janitor |
cve linked |
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2017-5753 |
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| 2018-06-11 15:09:13 |
Launchpad Janitor |
cve linked |
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2018-3639 |
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| 2018-06-11 15:09:13 |
Launchpad Janitor |
cve linked |
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2018-8087 |
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| 2018-06-11 15:10:16 |
Launchpad Janitor |
linux (Ubuntu Artful): status |
Fix Committed |
Fix Released |
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| 2018-06-11 15:10:16 |
Launchpad Janitor |
cve linked |
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2018-1068 |
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| 2018-06-11 15:10:16 |
Launchpad Janitor |
cve linked |
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2018-1092 |
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| 2018-06-11 15:10:16 |
Launchpad Janitor |
cve linked |
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2018-7492 |
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| 2018-06-11 15:10:16 |
Launchpad Janitor |
cve linked |
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2018-8781 |
|
| 2018-06-11 15:44:29 |
Frank Heimes |
ubuntu-z-systems: status |
Fix Committed |
Fix Released |
|
