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Bug 1780592 - [RHEL 8] strace gets confused by PID namespaces
Summary: [RHEL 8] strace gets confused by PID namespaces
Keywords:
Status: CLOSED DUPLICATE of bug 1725113
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: strace
Version: 8.2
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: 8.0
Assignee: Eugene Syromiatnikov
QA Contact: Edjunior Barbosa Machado
URL:
Whiteboard:
Depends On: 1035434 1804334 1807458
Blocks: 1725113
TreeView+ depends on / blocked
 
Reported: 2019-12-06 13:43 UTC by Edjunior Barbosa Machado
Modified: 2020-02-26 12:04 UTC (History)
9 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of: 1035434
Environment:
Last Closed: 2020-01-14 10:58:30 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)

Description Edjunior Barbosa Machado 2019-12-06 13:43:17 UTC 
Reproduced on RHEL-8.2 with:

strace-4.24-6.el8
kernel 4.18.0-159.el8
RHEL-8.2.0-20191203.0

+++ This bug was initially created as a clone of Bug #1035434 +++

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
Comment 2 Edjunior Barbosa Machado 2020-01-14 10:58:30 UTC 

*** This bug has been marked as a duplicate of bug 1725113 ***
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