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Bug 157424

Summary: U1 kernel 2.6.9-6.37.EL ptrace panics
Product: Red Hat Enterprise Linux 4 Reporter: Andrew Haley <aph>
Component: kernelAssignee: David Woodhouse <dwmw2>
Status: CLOSED CURRENTRELEASE QA Contact: Brian Brock <bbrock>
Severity: medium Docs Contact:
Priority: medium    
Version: 4.0CC: bjohnson, davej, jlaska
Target Milestone: ---   
Target Release: ---   
Hardware: powerpc   
OS: Linux   
Fixed In Version: RHEL 4 U2 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2006-08-21 15:06:51 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Description Flags
kernel dump
Proposed fix.
Upstream fix. none

Description Andrew Haley 2005-05-11 15:23:30 UTC
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.5) Gecko/20041107 Firefox/1.0

Description of problem:
kernel panic in ptrace

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

How reproducible:
Couldn't Reproduce

Steps to Reproduce:
1. run gdb

Actual Results:  kernel panic

Additional info:

This happens a few times per week under heavy debug load.

Comment 1 Andrew Haley 2005-05-11 15:25:49 UTC
Created attachment 114247 [details]
kernel dump

Comment 2 David Woodhouse 2005-05-11 15:44:05 UTC
Created attachment 114248 [details]
Proposed fix.

Yeah, looks obvious. We don't do the lazy fpu saving on SMP machines, and we
object violently to being asked to save the FPU for a non-current task.

Comment 3 David Woodhouse 2005-05-11 15:49:19 UTC
Hm. Actually I'm unconvinced the above is anything more than a workaround. The
BUG() will only trigger if MSR_FP is enabled for the child, and that really
shouldn't be happening. 

Comment 4 Suzanne Hillman 2005-05-11 20:50:36 UTC
*** Bug 157433 has been marked as a duplicate of this bug. ***

Comment 5 Ernie Petrides 2005-05-11 21:58:05 UTC
*** Bug 157433 has been marked as a duplicate of this bug. ***

Comment 6 Ernie Petrides 2005-05-11 22:00:00 UTC
Fixing kernel version and assigning.

Comment 7 David Woodhouse 2005-05-12 13:24:21 UTC
Created attachment 114293 [details]
Upstream fix.

This is the real fix. The problem we weren't correctly waiting for the inferior
to be taken off its CPU. Its register set really was in some other CPU, not in
the place we were looking for it, and that's why the FPU was still marked as

Comment 11 Dave Jones 2005-05-17 06:29:24 UTC
*** Bug 157831 has been marked as a duplicate of this bug. ***