Re: kern/39349: cpu affinity can make lwps non-schedulable

[Jason Thorpe <thorpej%shagadelic.org@localhost>]

The following reply was made to PR kern/39349; it has been noted by GNATS.

From: Jason Thorpe <thorpej%shagadelic.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: kern-bug-people%netbsd.org@localhost,
 gnats-admin%netbsd.org@localhost,
 netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/39349: cpu affinity can make lwps non-schedulable
Date: Thu, 14 Aug 2008 10:38:47 -0700

 On Aug 14, 2008, at 2:00 AM, yamt%mwd.biglobe.ne.jp@localhost wrote:
 
 >> Number:         39349
 >> Category:       kern
 >> Synopsis:       cpu affinity can make lwps non-schedulable
 >> Confidential:   no
 >> Severity:       serious
 >> Priority:       medium
 >> Responsible:    kern-bug-people
 >> State:          open
 >> Class:          sw-bug
 >> Submitter-Id:   net
 >> Arrival-Date:   Thu Aug 14 09:00:00 +0000 2008
 >> Originator:     YAMAMOTO Takashi <yamt%mwd.biglobe.ne.jp@localhost>
 >> Release:        NetBSD 4.99.72
 >> Organization:
 >      
 >> Environment:
 >> Description:
 >      try:
 >              # cpuctl offline 0
 >              # cpuctl identify 0
 >
 >      "cpuctl identify" binds itself to cpu0, which is offline.
 >      thus it will never be scheduled.  if it has a lock (eg. p->p_lock),
 >      the entire system will hang soon.
 
 Probably need to prevent binding to CPUs that have been taking  
 offline.  But what to do about CPUs that already have bound threads  
 (which is all of them, of course).  Perhaps we need to make note when  
 an LWP has taken a lock?
 
 
 >
 >> How-To-Repeat:
 >> Fix:
 >      
 >
 >> Unformatted:
 >      
 >      
 
 -- thorpej