Re: kernel fault when doing some I/O

From: Giovanni Trematerra <giovanni.trematerra_at_gmail.com>
Date: Mon, 1 Feb 2010 11:15:17 +0100
On Sun, Jan 31, 2010 at 8:36 PM, Aioanei Rares <bsdlisten_at_gmail.com> wrote:
>
> Hi everyone,
>
> I've been getting this several times but only now I could get a screenshot (it's a X-less VirtualBox host)
> The message I'm getting is the following :
>
> lock order reversal :
>  1st 0xffffff800a4c8698 bufwait (bufwait) _at_ /usr/src/sys/kern/vfs_bio.c:2559
>  2nd 0xffffff0002b81000 dirhash (dirhash) _at_ /usr/src/sys/ufs/ufs/ufs_dirhash.c:285
> KDB: stack backtrace:
> db_trace_self_wrapper() at db_trace_self_wrapper+0x2a
> _witness_debugger() at _witness_debugger+0x2e
> witness_checkorder() at witness_checkorder+0x81e
> _sx_xlock() at _sx_lock+0x55
> ufsdirhash_acquire() at ufsdirhash_acquire+0x33
> ufsdirhash_add() at ufsdirhash_add+0x19
> ufs_direnter() at ufs_direnter+0x889
> ufs_makeinode() at ufs_makeinode+0x38a
> VOP_CREATE_APV() at VOP_CREATE_APV+0x8d
> vn_open_cred() at vn_open_cred+0x473
> kern_openat() at kern_openat+0x179
> syscall() at syscall+0x1ae
> Xfast_syscall() at Xfast_syscall+0xe1
> --- syscall (5, FreeBSD ELF64, open), rip = 0x800c1095c, rsp = 0x7fffff1f9b38, rbp = 0x800e0a900 ---
>

That isn't a kernel fault but a LOR.
you can read more on LOR at http://sources.zabbadoz.net/freebsd/lor.html.
You got it because you compile your kernel with WITNESS option.

Bye

--
Gianni
Received on Mon Feb 01 2010 - 09:15:20 UTC

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