Re: kern/140313: [xen] [panic] FreeBSD8 RC2 as PV domU crashes during configure of security/libgcrypt

2010-12-26 Thread cperciva 
Synopsis: [xen] [panic] FreeBSD8 RC2 as PV domU crashes during configure of 
security/libgcrypt

State-Changed-From-To: open-patched
State-Changed-By: cperciva
State-Changed-When: Sun Dec 26 13:09:25 UTC 2010
State-Changed-Why: 
Fixed in HEAD.

http://www.freebsd.org/cgi/query-pr.cgi?pr=140313
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Re: kern/140313: commit references a PR

2010-12-26 Thread dfilter service 
The following reply was made to PR kern/140313; it has been noted by GNATS.

From: dfil...@freebsd.org (dfilter service)
To: bug-follo...@freebsd.org
Cc:  
Subject: Re: kern/140313: commit references a PR
Date: Sun, 26 Dec 2010 13:05:48 + (UTC)

 Author: cperciva
 Date: Sun Dec 26 13:05:43 2010
 New Revision: 216703
 URL: http://svn.freebsd.org/changeset/base/216703
 
 Log:
   Lock the vm page queue mutex in pmap_pte_release around the call
   to PMAP_SET_VA; this fixes a mutex-not-held panic when a process
   which called mlock(2) exits, and parallels a change made in
   pmap_pte 10 months ago (svn r204160).
   
   Note: The locking in this code is utterly broken.  We should not
   be using the VM page queue mutex to protect the queue of pending
   Xen page mapping hypervisor calls.  Even if it made sense to do
   so, this commit and r204160 introduce LORs between the vm page
   queue mutex and PMAP2mutex.
   
   (However, a possible deadlock is better than a guaranteed panic,
   and this change will hopefully make life easier for whoever fixes
   the Xen pmap locking in the future.)
   
   PR:  kern/140313
   MFC after:   3 days
 
 Modified:
   head/sys/i386/xen/pmap.c
 
 Modified: head/sys/i386/xen/pmap.c
 ==
 --- head/sys/i386/xen/pmap.c   Sun Dec 26 01:42:52 2010(r216702)
 +++ head/sys/i386/xen/pmap.c   Sun Dec 26 13:05:43 2010(r216703)
 @@ -1015,7 +1015,9 @@ pmap_pte_release(pt_entry_t *pte)
if ((pt_entry_t *)((vm_offset_t)pte  ~PAGE_MASK) == PADDR2) {
CTR1(KTR_PMAP, pmap_pte_release: pte=0x%jx,
*PMAP2);
 +  vm_page_lock_queues();
PT_SET_VA(PMAP2, 0, TRUE);
 +  vm_page_unlock_queues();
mtx_unlock(PMAP2mutex);
}
  }
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Re: kern/143069: [xen] [panic] Xen Kernel Panic - Memory modified after free (8.0-RELEASE)

2010-12-26 Thread Colin Percival 
The following reply was made to PR kern/143069; it has been noted by GNATS.

From: Colin Percival cperc...@freebsd.org
To: bug-follo...@freebsd.org, fbs...@s.rhythm.cx
Cc:  
Subject: Re: kern/143069: [xen] [panic] Xen Kernel Panic - Memory modified
 after free (8.0-RELEASE)
Date: Sun, 26 Dec 2010 22:08:56 -0800

 Hi Steve,
 
 I've fixed several bugs in the FreeBSD/Xen code over the past couple of
 months, including a few which could have caused the corruption you reported
 here; can you try with a recent (today's 9-CURRENT, or 8.2-RC1) tree and
 let me know if you can still reproduce this?
 
 Thanks,
 -- 
 Colin Percival
 Security Officer, FreeBSD | freebsd.org | The power to serve
 Founder / author, Tarsnap | tarsnap.com | Online backups for the truly paranoid
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