Date: Thu, 12 Mar 1998 10:30:52 -0800 (PST) From: Manfred Antar <root@mantar.slip.netcom.com> To: Tor Egge <Tor.Egge@idi.ntnu.no> Cc: current@FreeBSD.ORG, smp@FreeBSD.ORG Subject: Re: spkrtest locks up system Message-ID: <Pine.BSF.3.96.980312103015.315A-100000@mantar.slip.netcom.com> In-Reply-To: <199803121753.SAA05731@pat.idi.ntnu.no>
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On Thu, 12 Mar 1998, Tor Egge wrote:
> > On a current SMP system when I run spkrtest the system locks up.
> > On a kernel built around the 26th of Feb no problem. I have a old version
> > of spkrtest v1.0 by Eric S. Raymond (Feb 1990) that I use as sort of
> > a backup alarm clock. I was wondering why for the past couple of weeks
> > I'd wake up and the machine would be locked up. The current graphical
> > version does the same thing. I have no sound card installed. One time
> > it dropped into the debugger , now it just locks up. There was something
> > about _mplock if i remember right. There was alot of changes to current
> > around the end of Feb. (SMP and locking) and I'm not sure which is causing
> > the problem. Sorry I can't be of more help.
> > Manfred
>
> The following patch might be appropiate.
>
> Without this patch, the kernel can deadlock or panic when attempting
> to enter a critical region protected by disable_intr()/enable_intr(),
> since the mpintr_lock might be held by the last cpu having prezeroed
> a page.
>
> Index: sys/i386/i386/vm_machdep.c
> ===================================================================
> RCS file: /home/ncvs/src/sys/i386/i386/vm_machdep.c,v
> retrieving revision 1.101
> diff -u -r1.101 vm_machdep.c
> --- vm_machdep.c 1998/02/25 03:56:09 1.101
> +++ vm_machdep.c 1998/03/08 06:00:49
> @@ -950,7 +967,7 @@
> if (try_mplock()) {
> #endif
> s = splvm();
> - enable_intr();
> + __asm __volatile("sti" : : : "memory");
> m = vm_page_list_find(PQ_FREE, free_rover);
> if (m != NULL) {
> --(*vm_page_queues[m->queue].lcnt);
> @@ -973,7 +990,7 @@
> ++cnt_prezero;
> }
> splx(s);
> - disable_intr();
> + __asm __volatile("cli" : : : "memory");
> #ifdef SMP
> rel_mplock();
> return (1);
>
>
> - Tor Egge
>
That did the trick.
Thanks
Manfred
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