From owner-freebsd-hackers Mon Sep 24 18:27:47 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from peter3.wemm.org (c1315225-a.plstn1.sfba.home.com [24.14.150.180]) by hub.freebsd.org (Postfix) with ESMTP id 9BD6B37B411 for ; Mon, 24 Sep 2001 18:27:43 -0700 (PDT) Received: from overcee.netplex.com.au (overcee.wemm.org [10.0.0.3]) by peter3.wemm.org (8.11.0/8.11.0) with ESMTP id f8P1RhM20183 for ; Mon, 24 Sep 2001 18:27:43 -0700 (PDT) (envelope-from peter@wemm.org) Received: from wemm.org (localhost [127.0.0.1]) by overcee.netplex.com.au (Postfix) with ESMTP id 43E583808; Mon, 24 Sep 2001 18:27:43 -0700 (PDT) (envelope-from peter@wemm.org) X-Mailer: exmh version 2.3.1 01/18/2001 with nmh-1.0.4 To: Matt Dillon Cc: Ian Dowse , Julian Elischer , hackers@FreeBSD.ORG Subject: Re: VM Corruption - stumped, anyone have any ideas? In-Reply-To: <200109242322.f8ONMaT97469@earth.backplane.com> Date: Mon, 24 Sep 2001 18:27:43 -0700 From: Peter Wemm Message-Id: <20010925012743.43E583808@overcee.netplex.com.au> Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Matt Dillon wrote: > > :>The pointers in the last few entries of the vm_page_buckets array got > :>corrupted when an agument to a function that manipulated whatever was next > :>in ram was 0, and it turned out that it was 0 because > :> of some PTE flushing thing (you are the one that found it... remember?) > : > :I think I've also seen a few reports of programs exiting with > :"Profiling timer expired" messages with 4.4. These can be caused > :by stack overflows, since the p_timer[] array in struct pstats is > :one of the things that I think lives below the per-process kernel > :stack. I wonder if they are related? Stack overflows could result > :in corruption of local variables, after which anything could happen. > : > :That said, hardware problems are still a possiblilty. > : > :Ian > > Hmm. Do we have a guard page at the base of the per process kernel > stack? > > -Matt I did it as part of the KSE work in 5.x. It would be quite easy to do it for 4.x as well, but it makes a.out coredumps problematic. Also, "options UPAGES=4" is a pretty good defensive measure. Cheers, -Peter -- Peter Wemm - peter@FreeBSD.org; peter@yahoo-inc.com; peter@netplex.com.au "All of this is for nothing if we don't go to the stars" - JMS/B5 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message