From owner-freebsd-current Thu Dec 24 11:19:27 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id LAA08349 for freebsd-current-outgoing; Thu, 24 Dec 1998 11:19:27 -0800 (PST) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from wall.polstra.com (rtrwan160.accessone.com [206.213.115.74]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id LAA08343 for ; Thu, 24 Dec 1998 11:19:26 -0800 (PST) (envelope-from jdp@polstra.com) Received: from vashon.polstra.com (vashon.polstra.com [206.213.73.13]) by wall.polstra.com (8.9.1/8.9.1) with ESMTP id LAA08101; Thu, 24 Dec 1998 11:19:12 -0800 (PST) (envelope-from jdp@polstra.com) From: John Polstra Received: (from jdp@localhost) by vashon.polstra.com (8.9.1/8.9.1) id LAA01894; Thu, 24 Dec 1998 11:19:12 -0800 (PST) (envelope-from jdp@polstra.com) Date: Thu, 24 Dec 1998 11:19:12 -0800 (PST) Message-Id: <199812241919.LAA01894@vashon.polstra.com> To: mike@smith.net.au Subject: Re: trap 12 with interrupts disabled Newsgroups: polstra.freebsd.current In-Reply-To: <199812220225.SAA02191@dingo.cdrom.com> Organization: Polstra & Co., Seattle, WA Cc: current@FreeBSD.ORG Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG In article <199812220225.SAA02191@dingo.cdrom.com>, Mike Smith wrote: > > >>> pid 281 (Xaccel): trap 12 with interupts disabled > > >> > > >> Yes, I've noticed this one too. It seems to have crept in relatively > > >> recently, and strangely seems not to cause any problems. > > > > > > The diagnostic just warns of a bad situation (Xaccel has turned off > > > interrupts for some reason, and then pagefaulted), it doesn't mention > > > that it has in fact turned interrupts back on so that the pagefault can > > > be safely completed. > > > > If my page fault fails because I've blocked the interrupt, I'd expect > > some serious damage to happen to the process environment.n > > Usually you're lucky and something else turns them on unconditionally. > This test simply makes damn sure that if you take a fault interrupts > get turned back on. I'm still not entirely clear about the implications of this change. If I understand it right, the message is caused by a bug in Xaccel. The message and the re-enabling of interrupts was added in revision 1.129 of trap.c. The message now isn't particularly rare if you're running Xaccel. I got one almost immediately after updating my kernel. The bug didn't seem to hurt anything before. But now at least one person is reporting hangs on a system running Xaccel. That concerns me. Do the interrupts get turned back off again when control returns to Xaccel, or do they remain on? If Xaccel is assuming they're off, it seems bad to turn them on underfoot. Finally, do we have a contact at XiG to notify about this? John -- John Polstra jdp@polstra.com John D. Polstra & Co., Inc. Seattle, Washington USA "Nobody ever went broke underestimating the taste of the American public." -- H. L. Mencken To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message