** Changed in: ubuntu-z-systems
Status: Triaged => In Progress
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https://bugs.launchpad.net/bugs/1828166
Title:
perf top problem on z with Ubuntu 18.04
Status in Ubuntu on IBM z Systems:
In Progress
Status in linux package in Ubuntu:
Confirmed
Status in linux source package in Bionic:
In Progress
Status in linux source package in Cosmic:
Invalid
Status in linux source package in Disco:
In Progress
Bug description:
SRU Justification:
==================
[Impact]
* The perf top tool hangs and shows error messages, like 'Not enough
memory for annotating'
[Fix]
* b9c0a64901d5bdec6eafd38d1dc8fa0e2974fccb b9c0a64 "perf annotate: Fix
s390 gap between kernel end and module start"
* 12a6d2940b5f02b4b9f71ce098e3bb02bc24a9ea 12a6d29 "perf record: Fix
module size on s390"
[Test Case]
* start a benchmark (mem_alloc, but it doesn't really matter what)
* execute perf top in a second terminal
* the output of perf top is correct
* now stop the benchmark
* and perf top shows an error message, like "Not enough memory for
annotating '__irf_end' symbol!)"
* and perf top can't be exited anymore
[Regression Potential]
* The regression potential can be considered as medium since this
happens only while using the perf top tool
* and just 3 files are changed, and one of them is
arch/s390/util/machine.c
* but symbol and machine header in /tools/perf/util modified and
several loc added
[Other Info]
* cherry-pick was possible to bionic-master-next and to disco-master-
next (but used '--strategy=recursive -X theirs' for disco)
* adding the patches to disco is to avoid regressions
_________________________
perf top hangs and shows error messages
---uname output---
Linux weather 4.15.0-46-generic #49-Ubuntu SMP Wed Feb 6 09:32:27 UTC 2019
s390x s390x s390x GNU/Linux
---Steps to Reproduce---
I start a benchmark (mem_alloc, but it really doesn't matter) and then issue
perf top in a second terminal, the output from perf top is correct. Now I stop
the benchmark: perf top shows a error message (Not enough memory for annotating
'__irf_end' symbol!) and I can't quit from perf top anymore
Following analyse took place:
No problem with current kernel .
Bi-Secting of perf tool took place and following commit was found:
commit edeb0c90df3581b821a764052d185df985f8b8dc (HEAD, refs/bisect/bad)
Author: Arnaldo Carvalho de Melo <[email protected]>
Date: Tue Oct 16 17:08:29 2018 -0300
perf tools: Stop fallbacking to kallsyms for vdso symbols lookup
When you apply this patch the issue is gone, however it is contained
in these versions:
git tag --contains edeb0c90df3581b821
v4.19
v4.20
....
The level I was debugging was kernel 4.15 which does not contain this
patch.
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