Bug 1035434

Summary: strace gets confused by PID namespaces
Product: Red Hat Enterprise Linux 7 Reporter: Daniel Berrangé <berrange>
Component: straceAssignee: Eugene Syromiatnikov <esyr>
Status: CLOSED WONTFIX QA Contact: Edjunior Barbosa Machado <emachado>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 7.0CC: esyr, jmarchan, law, lmiksik, mjw, mnewsome, mpetlan
Target Milestone: rcKeywords: Reopened
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
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Doc Text:
Story Points: ---
Clone Of: 1035433
: 1725113 1780592 1804334 1807458 (view as bug list) Environment:
Last Closed: 2020-10-05 08:17:04 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On:    
Bug Blocks: 1725113, 1780592, 1790836, 1804334, 1807458    

Description Daniel Berrangé 2013-11-27 18:37:49 UTC 
Reproduced on RHEL-7 with

strace-4.8-3.el7
kernel-3.10.0-23.el7

+++ This bug was initially created as a clone of Bug #1035433 +++

Description of problem:
When using strace to debug an LXC problem I noticed that it gets a bit confused by PID namespaces.

I am running strace from host context, so I expect all PIDs it reports to be host PIDs. When strace creates new log files (due to the -ff CLI option) it names them based on the host PIDs, which is good. Inside these log files though the clone() syscalls are reporting container PIDs which is bad. This means you can't correlate the clone() syscalls  with the log files strace is creating.

If running strace from inside container context it correctly uses container PIDs in both places.

Version-Release number of selected component (if applicable):
strace-4.8-1.fc19.x86_64
kernel-3.11.9-200.fc19.x86_64

How reproducible:
Always

Steps to Reproduce:
1. From the host run

# strace -f -ff -o s.log unshare --pid -- /bin/sh

and at the shell prompt execute '/bin/sh' again. Then do it again. And again.. Then exit back to the host context

You should now have several log files
 

Actual results:
# ls s.log.*
s.log.9851  s.log.9860  s.log.9861  s.log.9862
# grep clone s.log.98*
s.log.9851:clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7fe81e7b6a10) = 9860
s.log.9860:clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f47d93aca10) = 2
s.log.9861:clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f9962d34a10) = 3


Expected results:
# ls s.log.*
s.log.9851  s.log.9860  s.log.9861  s.log.9862
# grep clone s.log.98*
s.log.9851:clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7fe81e7b6a10) = 9860
s.log.9860:clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f47d93aca10) = 9861
s.log.9861:clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f9962d34a10) = 9862


Additional info:
Comment 2 Jeff Law 2013-11-27 19:01:01 UTC 
Not getting into RHEL 7.0 unless it's addressed upstream.
Comment 3 RHEL Program Management 2013-11-27 19:26:25 UTC 
Development Management has reviewed and declined this request.
You may appeal this decision by reopening this request.
Comment 13 Eugene Syromiatnikov 2019-03-11 13:10:46 UTC 
It's unlikely that I'll be able to push the required changes to upstream during 7.7 development time frame, moving to 7.8.
Comment 16 Jerome Marchand 2020-10-05 08:17:04 UTC 
Only critical bugs will be fixed in RHEL 7 after 7.9.