| 2020-11-19 14:59:29 |
bugproxy |
bug |
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added bug |
| 2020-11-19 14:59:31 |
bugproxy |
tags |
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architecture-s39064 bugnameltc-189321 severity-critical targetmilestone-inin20041 |
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| 2020-11-19 14:59:33 |
bugproxy |
ubuntu: assignee |
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Skipper Bug Screeners (skipper-screen-team) |
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| 2020-11-19 14:59:37 |
bugproxy |
affects |
ubuntu |
linux (Ubuntu) |
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| 2020-11-19 15:02:53 |
Frank Heimes |
bug task added |
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ubuntu-z-systems |
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| 2020-11-19 15:04:33 |
Frank Heimes |
ubuntu-z-systems: importance |
Undecided |
High |
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| 2020-11-19 15:04:59 |
Frank Heimes |
ubuntu-z-systems: assignee |
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Skipper Bug Screeners (skipper-screen-team) |
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| 2020-11-19 15:05:49 |
Frank Heimes |
nominated for series |
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Ubuntu Bionic |
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| 2020-11-19 15:05:49 |
Frank Heimes |
bug task added |
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linux (Ubuntu Bionic) |
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| 2020-11-19 15:05:49 |
Frank Heimes |
nominated for series |
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Ubuntu Hirsute |
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| 2020-11-19 15:05:49 |
Frank Heimes |
bug task added |
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linux (Ubuntu Hirsute) |
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| 2020-11-19 15:05:49 |
Frank Heimes |
nominated for series |
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Ubuntu Focal |
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| 2020-11-19 15:05:49 |
Frank Heimes |
bug task added |
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linux (Ubuntu Focal) |
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| 2020-11-19 15:05:49 |
Frank Heimes |
nominated for series |
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Ubuntu Groovy |
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| 2020-11-19 15:05:49 |
Frank Heimes |
bug task added |
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linux (Ubuntu Groovy) |
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| 2020-11-19 15:19:36 |
bugproxy |
tags |
architecture-s39064 bugnameltc-189321 severity-critical targetmilestone-inin20041 |
architecture-s39064 bugnameltc-189321 severity-high targetmilestone-inin20041 |
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| 2020-11-19 15:40:13 |
Frank Heimes |
linux (Ubuntu Hirsute): assignee |
Skipper Bug Screeners (skipper-screen-team) |
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| 2020-11-19 15:40:20 |
Frank Heimes |
linux (Ubuntu Hirsute): status |
New |
Fix Released |
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| 2020-11-19 15:40:26 |
Frank Heimes |
linux (Ubuntu Groovy): status |
New |
Fix Released |
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| 2020-11-19 15:40:33 |
Frank Heimes |
ubuntu-z-systems: status |
New |
Triaged |
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| 2020-11-19 15:41:05 |
Frank Heimes |
summary |
[UBUNUT 20.04] s390: dbginfo.sh triggers kernel panic, reading from /sys/kernel/mm/page_idle/bitmap |
s390: dbginfo.sh triggers kernel panic, reading from /sys/kernel/mm/page_idle/bitmap |
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| 2020-11-20 14:19:25 |
Frank Heimes |
attachment added |
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mm_page_idle.c_skip_offline_pages-backport.patch https://bugs.launchpad.net/ubuntu-z-systems/+bug/1904884/+attachment/5436359/+files/mm_page_idle.c_skip_offline_pages-backport.patch |
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| 2020-11-20 15:21:17 |
Frank Heimes |
attachment removed |
mm_page_idle.c_skip_offline_pages-backport.patch https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1904884/+attachment/5436359/+files/mm_page_idle.c_skip_offline_pages-backport.patch |
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| 2020-11-20 15:27:57 |
bugproxy |
attachment added |
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mm_page_idle.c_skip_offline_pages-backport.patch https://bugs.launchpad.net/bugs/1904884/+attachment/5436362/+files/mm_page_idle.c_skip_offline_pages-backport.patch |
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| 2020-11-20 15:37:52 |
Frank Heimes |
attachment removed |
mm_page_idle.c_skip_offline_pages-backport.patch https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1904884/+attachment/5436362/+files/mm_page_idle.c_skip_offline_pages-backport.patch |
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| 2020-11-20 15:38:13 |
bugproxy |
attachment added |
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mm_page_idle.c_skip_offline_pages-backport.patch https://bugs.launchpad.net/bugs/1904884/+attachment/5436363/+files/mm_page_idle.c_skip_offline_pages-backport.patch |
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| 2020-11-23 10:12:38 |
Frank Heimes |
attachment removed |
mm_page_idle.c_skip_offline_pages-backport.patch https://bugs.launchpad.net/ubuntu-z-systems/+bug/1904884/+attachment/5436363/+files/mm_page_idle.c_skip_offline_pages-backport.patch |
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| 2020-11-23 14:20:34 |
Frank Heimes |
attachment added |
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mm_page_idle.c_skip_offline_pages-backport_to_bionic.patch https://bugs.launchpad.net/ubuntu-z-systems/+bug/1904884/+attachment/5437240/+files/mm_page_idle.c_skip_offline_pages-backport_to_bionic.patch |
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| 2020-11-23 18:56:32 |
Frank Heimes |
description |
System hangs on dbginfo.sh script execution.
Solution:
Commit 92fb1db26eef ("mm/page_idle.c: skip offline pages")
Included upstream since kernel v5.8, so it is already included in Ubuntu 20.10, but not in 20.04 and earlier.
Commit 92fb1db26eef ("mm/page_idle.c: skip offline pages") applies cleanly on ubuntu-focal, but not on ubuntu-bionic.
Adjustment / backport for bionic should be trivial, but it is not IBM code and therefore the backport will be requested here by Canonical. |
SRU Justification:
==================
[Impact]
* While executing dbginfo.sh (a script to collect runtime, configuration, and trace information on s390x) the systems hangs.
* This is because 'idle page tracking' users can pass random pfn, that might be mapped to
an offline page - and attempts to access offline pages lead to the hang.
* It needs to be avoided that such pages are accessed.
* The upstream commit modifies 'page_idle_get_page()' to use 'pfn_to_online_page()' instead of a
'pfn_valid()' and 'pfn_to_page()' combination, so that the pfn mapped to an offline page is skipped.
[Fix]
* 92fb1db26eef "mm/page_idle.c: skip offline pages"
[Test Case]
* IBM Z or LinuxONE hardware with Ubuntu Server 18.04 (GA kernel, 4.15) installed.
* Execute a test application that tries to access offline pages.
* Or execute dbginfo.sh with having some offline (idle) pages in the system.
[Regression Potential]
* There is a certain regression risk, especially for bionic, since the structure in the kernel 4.15 is a bit different compared to kernel 5.4 (and newer).
* However, for newer kernels the modification is pretty save, since it's upstream accepted since kernel 5.8 and with that already inluded in hirsute and groovy.
* And the patch is fine (and cherry picks cleanly) for focal as well.
* For bionic there is a slightly conflicting context, since the struct 'zone' was replaced by 'pg_data_t *pgdat' (by another commit: 92fb1db26eef), but that change (or any change to the struct zone) would not be necessary to fix the uninitialized struct page access.
* Hence the upstream commit/patch needs to be adjusted/backported to bionic 4.15, largely by replacing line 'pg_data_t *pgdat;' with 'struct zone *zone;' (or actually leaving this line).
* But this needs to be carefully considered, since the handling of idle pages could be harmful, in the end it could make things even worse, means break even more.
[Other]
* The patch got upstream accepted with kernel v5.8, hence it's already is in groovy and hirsute.
* The upstream commit cherry picks cleanly to focal, but for bionic a backport is needed.
* Hence this kernel SRU request is for focal (cherry-pick) and bionic (backport).
__________
System hangs on dbginfo.sh script execution.
Solution:
Commit 92fb1db26eef ("mm/page_idle.c: skip offline pages")
Included upstream since kernel v5.8, so it is already included in Ubuntu 20.10, but not in 20.04 and earlier.
Commit 92fb1db26eef ("mm/page_idle.c: skip offline pages") applies cleanly on ubuntu-focal, but not on ubuntu-bionic.
Adjustment / backport for bionic should be trivial, but it is not IBM code and therefore the backport will be requested here by Canonical. |
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| 2020-11-24 16:41:25 |
Frank Heimes |
linux (Ubuntu Focal): status |
New |
In Progress |
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| 2020-11-24 16:41:30 |
Frank Heimes |
linux (Ubuntu Bionic): status |
New |
In Progress |
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| 2020-11-24 16:41:36 |
Frank Heimes |
ubuntu-z-systems: status |
Triaged |
In Progress |
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| 2020-11-27 13:00:39 |
Stefan Bader |
linux (Ubuntu Focal): importance |
Undecided |
Medium |
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| 2020-11-27 13:00:39 |
Stefan Bader |
linux (Ubuntu Focal): status |
In Progress |
Fix Committed |
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| 2020-11-27 22:50:17 |
Kelsey Steele |
linux (Ubuntu Bionic): status |
In Progress |
Fix Committed |
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| 2020-11-28 07:45:40 |
Frank Heimes |
ubuntu-z-systems: status |
In Progress |
Fix Committed |
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| 2020-11-30 23:47:48 |
Ubuntu Kernel Bot |
tags |
architecture-s39064 bugnameltc-189321 severity-high targetmilestone-inin20041 |
architecture-s39064 bugnameltc-189321 severity-high targetmilestone-inin20041 verification-needed-focal |
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| 2020-12-01 14:39:07 |
Frank Heimes |
tags |
architecture-s39064 bugnameltc-189321 severity-high targetmilestone-inin20041 verification-needed-focal |
architecture-s39064 bugnameltc-189321 severity-high targetmilestone-inin20041 verification-done-focal |
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| 2020-12-02 12:29:25 |
Ubuntu Kernel Bot |
tags |
architecture-s39064 bugnameltc-189321 severity-high targetmilestone-inin20041 verification-done-focal |
architecture-s39064 bugnameltc-189321 severity-high targetmilestone-inin20041 verification-done-focal verification-needed-bionic |
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| 2020-12-02 13:42:56 |
Frank Heimes |
tags |
architecture-s39064 bugnameltc-189321 severity-high targetmilestone-inin20041 verification-done-focal verification-needed-bionic |
architecture-s39064 bugnameltc-189321 severity-high targetmilestone-inin20041 verification-done-bionic verification-done-focal |
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| 2021-01-04 13:54:06 |
Launchpad Janitor |
linux (Ubuntu Focal): status |
Fix Committed |
Fix Released |
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| 2021-01-04 15:46:58 |
Launchpad Janitor |
linux (Ubuntu Bionic): status |
Fix Committed |
Fix Released |
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| 2021-01-04 15:46:58 |
Launchpad Janitor |
cve linked |
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2019-19770 |
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| 2021-01-04 16:10:12 |
Frank Heimes |
ubuntu-z-systems: status |
Fix Committed |
Fix Released |
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