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Re: port-arm/38950 (shark, hpcarm kernels prone to hard hangs on process

Subject: Re: port-arm/38950 shark, hpcarm kernels prone to hard hangs on process exit
From: Rafal Boni
Date: Tue, 24 Jun 2008 00:35:12 UTC
Newsgroups: fa.netbsd.bugs

The following reply was made to PR port-arm/38950; it has been noted by GNATS.

From: Rafal Boni <rafal@xxxxxxxxx>
To: gnats-bugs@xxxxxxxxxx
Cc: port-arm-maintainer@xxxxxxxxxx, gnats-admin@xxxxxxxxxx,
 netbsd-bugs@xxxxxxxxxx
Subject: Re: port-arm/38950 (shark,
 hpcarm kernels prone to hard hangs on process exit)
Date: Mon, 23 Jun 2008 20:33:37 -0400

 Steve Woodford wrote:
 >  On Friday 20 June 2008 04:35:01 Rafal Boni wrote:
 >  
 >  >  This just occurred to me after having filed this in the "I don't
 >  > have time to think about it right now" bin.  The issue here is that
 >  > the pmap code is using the last-active-lwp as a proxy for
 >  > last-active-pmap.  What we should do is just save the pmap pointed to
 >  > by the last-active-lwp vs. the lwp itself.
 >  
 >  While that may solve the problem, it may well work against the intention 
 >  of "last-active-pmap", which is to reduce the impact of 
 >  context-switching between user-mode processes/lwps.
 >  
 >  A simple fix would be to add the following to pmap_deactivate():
 [...fixed snip'ed to avoid repetition in GNATS...]
 
 The fix does indeed work as advertised, and the shark is happily 
 building packages currently.  I haven't yet tested on hpcarm but have no 
 reason to think it won't work there as well.
 
 --rafal
 

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