Bug 1572501

Summary: RHEL7.5 - backtraces no longer work with systemtap but worked in RHEL7.4 - adding 'nokaslr' on kernel commandline makes them work again [rhel-7.5.z]
Product: Red Hat Enterprise Linux 7 Reporter: Oneata Mircea Teodor <toneata>
Component: systemtapAssignee: Frank Ch. Eigler <fche>
Status: CLOSED ERRATA QA Contact: Martin Cermak <mcermak>
Severity: unspecified Docs Contact: Vladimír Slávik <vslavik>
Priority: urgent    
Version: 7.5CC: alanm, dsmith, dwysocha, fche, fsorenso, jistone, jmoyer, kwalker, lberk, mcermak, mjw, sjohnsto, smakarov, stalexan, tbecker, wcohen
Target Milestone: rcKeywords: Regression, ZStream
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: systemtap-3.2-8.el7_5 Doc Type: Bug Fix
Doc Text:
Because of changes in the kernel related to address space layout randomization (ASLR), kernel backtraces collected by the SystemTap tool were incomplete. SystemTap has been extended to handle this situation. As a result, SystemTap provides complete kernel backtraces.
 Story Points: ---
Clone Of: 1567356 Environment:
Last Closed: 2018-06-26 16:48:44 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1567356    
Bug Blocks:    
Attachments:
Description Flags
stap -DDEBUG_UNWIND=1 -DDEBUG_SYMBOLS -DDEBUG_TRANS --all-modules -vwe 'probe kernel.function("kmem_cache_alloc") { print_backtrace(); exit() }' >& stap_results.out none

Description Oneata Mircea Teodor 2018-04-27 07:28:35 UTC 
This bug has been copied from bug #1567356 and has been proposed to be backported to 7.5 z-stream (EUS).
Comment 5 Jeff Moyer 2018-05-10 16:33:29 UTC 
*** Bug 1576845 has been marked as a duplicate of this bug. ***
Comment 12 errata-xmlrpc 2018-06-26 16:48:44 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2018:1981
Comment 13 William Cohen 2019-02-22 17:01:21 UTC 
Created attachment 1537609 [details]
stap  -DDEBUG_UNWIND=1 -DDEBUG_SYMBOLS -DDEBUG_TRANS --all-modules -vwe 'probe kernel.function("kmem_cache_alloc") { print_backtrace(); exit() }' >& stap_results.out

Set more debug variables for systemtap and another run with:

stap  -DDEBUG_UNWIND=1 -DDEBUG_SYMBOLS -DDEBUG_TRANS --all-modules -vwe 'probe kernel.function("kmem_cache_alloc") { print_backtrace(); exit() }' >& stap_results.out