Date: Mon, 24 Sep 2001 18:27:43 -0700 From: Peter Wemm <peter@wemm.org> To: Matt Dillon <dillon@earth.backplane.com> Cc: Ian Dowse <iedowse@maths.tcd.ie>, Julian Elischer <julian@elischer.org>, hackers@FreeBSD.ORG Subject: Re: VM Corruption - stumped, anyone have any ideas? Message-ID: <20010925012743.43E583808@overcee.netplex.com.au> In-Reply-To: <200109242322.f8ONMaT97469@earth.backplane.com>
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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
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