Bug 1467723

Summary:	regression: perf commit cc1582c231ea breaks debugging with "rr"
Product:	[Fedora] Fedora	Reporter:	Michael Stahl <mstahl>
Component:	kernel	Assignee:	Kernel Maintainer List <kernel-maint>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	25	CC:	gansalmon, ichavero, itamar, jonathan, kernel-maint, madhu.chinakonda, mchehab
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Last Closed:	2017-09-29 18:51:46 UTC	Type:	Bug
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Description Michael Stahl 2017-07-04 21:06:51 UTC

Description of problem:
replay debugging with rr doesn't work

Version-Release number of selected component (if applicable):
kernel-4.11.7-200.fc25.x86_64

How reproducible:
Sometimes, but not always

Steps to Reproduce:
1. rr record instdir/program/soffice
2. trigger some hard to reproduce crash
3. rr replay ~/.local/share/rr/latest

Actual results:

[ERROR /home/roc/rr/rr/src/ReplaySession.cc:545:guard_overshoot() errno: SUCCESS] Replay diverged; target registers mismatched:
[FATAL /home/roc/rr/rr/src/ReplaySession.cc:549:guard_overshoot() errno: SUCCESS]
 (task 14923 (rec:14535) at time 42867)
 -> Assertion `false' failed to hold. overshot target ticks=2734735504 by 33386


Expected results:

working replay debugging

Additional info:

4.11.3 does not have this problem: kernel-core-4.11.3-202.fc25.x86_64

rr developers claim this is a regression of commit cc1582c231ea
"perf/core: Drop kernel samples even though :u is specified"

LKML thread:
http://www.spinics.net/lists/kernel/msg2544195.html

Comment 1 Michael Stahl 2017-09-29 18:51:46 UTC

works for me now, was fixed reportedly in 4.12.4 and 4.13