Bug 113892 - System freezes when strace attaches to XFree86
Summary: System freezes when strace attaches to XFree86
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Fedora
Classification: Fedora
Component: XFree86
Version: 1
Hardware: i386
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Mike A. Harris
QA Contact: David Lawrence
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2004-01-19 22:44 UTC by Lars Damerow
Modified: 2007-11-30 22:10 UTC (History)
0 users

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2004-01-20 00:46:25 UTC
Type: ---
Embargoed:


Attachments (Terms of Use)
magic sysrq output of a machine in the frozen state (66.11 KB, text/plain)
2004-01-19 22:45 UTC, Lars Damerow
no flags Details
magic sysrq task list output, round 2 (58.25 KB, text/plain)
2004-01-19 22:45 UTC, Lars Damerow
no flags Details

Description Lars Damerow 2004-01-19 22:44:06 UTC
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4.1)
Gecko/20031114 Epiphany/1.0.4

Description of problem:
While trying to determine what XFree86 was doing, I ran 'strace -f -p
<pid>' on it. I got a few lines of unsurprising output and then the
machine froze up. I connected to the machine remotely and kill -9 X,
which returned the machine to a usable state.

I can reproduce this at will on several machines, and will include
magic-sysrq task list output from a machine in the frozen state.

Version-Release number of selected component (if applicable):
XFree86-4.3.0-42

How reproducible:
Always

Steps to Reproduce:
1. start X windows
2. run 'strace -f -p <pid>', where <pid> is the PID of the X binary
3. watch the machine freeze after spitting out some output.
4. if the machine doesn't freeze on its own, move the mouse.
    

Actual Results:  the machine is unresponsive, except for network
connections.

Expected Results:  strace should have shown process output until I hit
ctrl-c. the machine
shouldn't have frozen.

Additional info:

Comment 1 Lars Damerow 2004-01-19 22:45:03 UTC
Created attachment 97111 [details]
magic sysrq output of a machine in the frozen state

Comment 2 Lars Damerow 2004-01-19 22:45:39 UTC
Created attachment 97112 [details]
magic sysrq task list output, round 2

Comment 3 Mike A. Harris 2004-01-20 00:45:33 UTC
When attempting to debug the X server, or any of its modules,
you must not run the debugging software from within the X server
you are attempting to debug/strace/etc.  You must run the X server
alone, and run the debugger/strace/etc. from a remote network
session or serial console, or other access mechanism.

Closing as NOTABUG.

Comment 4 Lars Damerow 2004-01-20 01:10:46 UTC
gotcha. thanks!
-lars


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