Date: Tue, 24 Jan 2012 14:09:03 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: Gleb Smirnoff <glebius@FreeBSD.org> Cc: current@FreeBSD.org Subject: Re: new panic in cpu_reset() with WITNESS Message-ID: <4F1E9F5F.8080209@FreeBSD.org> In-Reply-To: <20120124115424.GX16676@glebius.int.ru> References: <4F1ABFF3.9090305@FreeBSD.org> <20120122163539.GF16676@glebius.int.ru> <4F1D18A5.8010006@FreeBSD.org> <20120123130743.GI16676@glebius.int.ru> <4F1D6830.60602@FreeBSD.org> <20120123162410.GN16676@glebius.int.ru> <20120123162606.GO16676@FreeBSD.org> <4F1D8E2B.30800@FreeBSD.org> <20120123164659.GQ16676@glebius.int.ru> <4F1D9128.3030501@FreeBSD.org> <20120124115424.GX16676@glebius.int.ru>
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on 24/01/2012 13:54 Gleb Smirnoff said the following:
> On Mon, Jan 23, 2012 at 06:56:08PM +0200, Andriy Gapon wrote:
> A> on 23/01/2012 18:46 Gleb Smirnoff said the following:
> A> > On Mon, Jan 23, 2012 at 06:43:23PM +0200, Andriy Gapon wrote:
> A> > A> > db> bt
> A> > A> > Tracing pid 1 tid 100001 td 0xfffffe0001d5e000
> A> > A> > kdb_enter() at kdb_enter+0x3b
> A> > A> > panic() at panic+0x1c7
> A> > A> > _mtx_lock_spin_flags() at _mtx_lock_spin_flags+0x10f
> A> > A> > cnputs() at cnputs+0x7a
> A> > A> > vprintf() at vprintf+0xcb
> A> > A> > printf() at printf+0x67
> A> > A> > db_putc() at db_putc+0x81
> A> > A>
> A> > A> Ah, db_putc does something different from what I expected.
> A> > A> Can you hack it to never use printf?
> A> >
> A> > Just cut printfs from db_putc()?
> A>
> A> Make the following condition be always false:
> A>
> A> if (!kdb_active || ddb_use_printf) {
> A>
> A> E.g.:
> A>
> A> if (0) {
>
> With this change + s/printf/db_printf/ in subr_witness.c I've
> got the following during reboot:
>
> Rebooting...
> lllock order reversal:
> 1st 0xffffffff80937140 smp rendezvous (smp rendezvous) @ /usr/src/head/sys/kern/kern_shutdown.c:542
> 2nd 0xffffffff80b13280 syscons video lock (syscons video lock) @ /usr/src/head/sys/dev/syscons/syscons.c:1921
> panic: mtx_lock_spin: recursed on non-recursive mutex cnputs_mtx @ /usr/src/head/sys/kern/kern_cons.c:500
Can you disable video console?
--
Andriy Gapon
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