Date: Tue, 26 Jun 2001 21:45:44 -0700 (PDT) From: John Baldwin <jhb@FreeBSD.org> To: Makoto MATSUSHITA <matusita@jp.FreeBSD.org> Cc: current@freebsd.org Subject: Re: lock order reversal Message-ID: <XFMail.010626214544.jhb@FreeBSD.org> In-Reply-To: <20010627101230R.matusita@jp.FreeBSD.org>
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On 27-Jun-01 Makoto MATSUSHITA wrote:
>
> matusita> lock order reversal
> matusita> 1st 0xc5d2043c process lock @ ../../vm/vm_glue.c:487
> matusita> 2nd 0xc05a9ec0 lockmgr interlock @ ../../kern/kern_lock.c:239
>
> I've caught tracelog of this reversal, with debug.witness_ddb=1.
> Here's console log:
>
> lock order reversal
> 1st 0xc5e3cfdc process lock @ ../../vm/vm_glue.c:487
> 2nd 0xc05a9f80 lockmgr interlock @ ../../kern/kern_lock.c:239
> Debugger("witness_lock")
> Stopped at Debugger+0x44: pushl %ebx
> db> trace
> Debugger(c02bd5ae) at Debugger+0x44
> witness_lock(c05a9f80,8,c02b8d54,ef) at witness_lock+0x90d
> lockmgr(c5dbe7d0,12,0,c5420640) at lockmgr+0x97
> swapout_procs(1,c02686e0,c5420640,0,c582df94) at swapout_procs+0xc46
> vm_daemon(0,c582dfa8) at vm_daemon+0x128
> fork_exit(c02686e0,0,c582dfa8) at fork_exit+0xb4
> fork_trampoline() at fork_trampoline+0x8
> db>
>
> I don't know whether it is reproducible, but it's early morning (6 AM),
> mkisofs(1) is just running to make an ISO image for me (for backup).
Ok, this one is due to braindeadedness in lockmgr(), and will just have to stay
the way it is until vm map locks switch to being sx locks instead of lockmgr
locks.
--
John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
PGP Key: http://www.baldwin.cx/~john/pgpkey.asc
"Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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