Date: Mon, 10 May 1999 14:11:03 -0700 From: Cy Schubert <cschuber@uumail.gov.bc.ca> To: Mike Tancsa <mike@sentex.net> Cc: Cy Schubert - ITSD Open Systems Group <Cy.Schubert@uumail.gov.bc.ca>, freebsd-stable@freebsd.org, julian@freebsd.org, dillon@freebsd.org, luoqi@freebsd.org Subject: Re: vm_fault deadlock and PR 8416 (was Re: Strange reboot saga ) Message-ID: <199905102111.OAA50817@passer.osg.gov.bc.ca> In-Reply-To: Your message of "Mon, 10 May 1999 15:19:33 EDT." <3.0.5.32.19990510151933.017f1b90@staff.sentex.ca>
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In message <3.0.5.32.19990510151933.017f1b90@staff.sentex.ca>, Mike
Tancsa writ
es:
> At 12:11 PM 5/10/99 -0700, Cy Schubert wrote:
> >I remember trying this exploit about a month ago when it was first
> >announced. It locked the system up solid within seconds. After
> >applying the patches from PR 8416 I currently have four copies of
> >find and one tripwire running for over an hour and a half, with no
> >hang. The patches from PR 8416 appear to have fixed the hang.
>
>
> That is most excellent... Is there any reason why this patch has not been
> applied to the tree ? i.e. does it have any adverse side effects
> preventing it from being committed ?
>
> ---Mike
>
Version 1.24 of kern_lock.c does have the fix, however it relies on
macros that only exist in -current. Not being a FreeBSD kernel
wizard, I can only guess that the version of the fix in PR 8416 may
cause other problems or it might just be that version 1.24 of
kern_lock.c is simply a more elegant solution. If it is the
latter, then temporarily committing the PR 8416 version into
-stable might provide some relief until a more permanent solution
based on version 1.24 can be engineered into -stable.
Version 1.24 of kern_lock.c only fixes read()/mmap() deadlocks.
Write()/mmap() deadlocks still have the potential of hanging the
system, which may answer why the solution hasn't been MFC'd yet, as
it's only a partial solution. [IMO a partial solution is better
than nothing, but then again I'm not a FreeBSD kernel wizard.]
Regards, Phone: (250)387-8437
Cy Schubert Fax: (250)387-5766
Open Systems Group Internet: Cy.Schubert@uumail.gov.bc.ca
ITSD Cy.Schubert@gems8.gov.bc.ca
Province of BC
"e**(i*pi)+1=0"
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