From owner-freebsd-xen@FreeBSD.ORG  Sun Dec 26 13:10:13 2010
Return-Path: <owner-freebsd-xen@FreeBSD.ORG>
Delivered-To: freebsd-xen@hub.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 06CDD1065693
	for <freebsd-xen@hub.freebsd.org>; Sun, 26 Dec 2010 13:10:13 +0000 (UTC)
	(envelope-from gnats@FreeBSD.org)
Received: from freefall.freebsd.org (freefall.freebsd.org
	[IPv6:2001:4f8:fff6::28])
	by mx1.freebsd.org (Postfix) with ESMTP id EB1998FC17
	for <freebsd-xen@hub.freebsd.org>; Sun, 26 Dec 2010 13:10:12 +0000 (UTC)
Received: from freefall.freebsd.org (localhost [127.0.0.1])
	by freefall.freebsd.org (8.14.4/8.14.4) with ESMTP id oBQDAC5P010338
	for <freebsd-xen@freefall.freebsd.org>; Sun, 26 Dec 2010 13:10:12 GMT
	(envelope-from gnats@freefall.freebsd.org)
Received: (from gnats@localhost)
	by freefall.freebsd.org (8.14.4/8.14.4/Submit) id oBQDACZ5010337;
	Sun, 26 Dec 2010 13:10:12 GMT (envelope-from gnats)
Date: Sun, 26 Dec 2010 13:10:12 GMT
Message-Id: <201012261310.oBQDACZ5010337@freefall.freebsd.org>
To: freebsd-xen@FreeBSD.org
From: dfilter@FreeBSD.ORG (dfilter service)
Cc: 
Subject: Re: kern/140313: commit references a PR
X-BeenThere: freebsd-xen@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
Reply-To: dfilter service <dfilter@FreeBSD.ORG>
List-Id: Discussion of the freebsd port to xen - implementation and usage
	<freebsd-xen.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-xen>,
	<mailto:freebsd-xen-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-xen>
List-Post: <mailto:freebsd-xen@freebsd.org>
List-Help: <mailto:freebsd-xen-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-xen>,
	<mailto:freebsd-xen-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 26 Dec 2010 13:10:13 -0000

The following reply was made to PR kern/140313; it has been noted by GNATS.

From: dfilter@FreeBSD.ORG (dfilter service)
To: bug-followup@FreeBSD.org
Cc:  
Subject: Re: kern/140313: commit references a PR
Date: Sun, 26 Dec 2010 13:05:48 +0000 (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);
  	}
  }
 _______________________________________________
 svn-src-all@freebsd.org mailing list
 http://lists.freebsd.org/mailman/listinfo/svn-src-all
 To unsubscribe, send any mail to "svn-src-all-unsubscribe@freebsd.org"